Lithium-ion polymer batteries are widely used due to their long life and high capacity. However, there are some issues that can arise, such as swelling, unsatisfactory safety performance, and accelerated cycle attenuation.
This article will primarily focus on battery swelling and its causes, which can be divided into two categories: the first is a result of a change in thickness of the electrode, and the other is a result of the gas produced by the oxidation and decomposition of electrolytes.
The change in thickness of the electrode pole piece
When a lithium battery is used, the thickness of the electrode pole pieces, especially the graphite negative electrodes, will change to a certain extent.
Lithium batteries are prone to swelling after high-temperature storage and circulation, and the thickness growth rate is about 6% to 20%. Of this, the expansion rate of the positive electrode is only 4%, the negative electrodes is more than 20%.
The fundamental reason for the increase in the thickness of the lithium battery pole piece is due to the nature of graphite. The negative electrode graphite forms LiCx (LiC24, LiC12, LiC6, etc.) when lithium is inserted, and the lattice spacing changes, resulting in microscopic internal stress and an expansion of the negative electrode.
The figure is the schematic diagram of the structure change of the graphite anode plate in the process of placement, charge, and discharge.
The expansion of graphite negative electrodes is mainly caused by irreversible expansion after lithium insertion. This part of the expansion is mainly related to the particle size, the adhesive, and the structure of the pole piece. The expansion of the negative electrode causes the core to deform, which in turn causes the following: a cavity between the electrode and the diaphragm, micro-cracks in the negative electrode particles, breaking and reorganizing of the solid electrolyte interface (SEI) membrane, the consummation of electrolytes, and deterioration of the cycle performance.
There are many factors that affect the thickness of the negative pole piece although the properties of the adhesive and the structural parameters of the pole piece are the two most important reasons.
The commonly used bonding agent for graphite negative electrodes is SBR. Different bonding agents have different elastic modulus and mechanical strength and have different effects on the thickness of the pole piece. The rolling force after the pole piece is coated also affects the thickness of the negative pole piece in battery use.
When the amount of SBR added is inconsistent, the pressure on the pole piece during rolling will be different. Different pressures will cause a certain difference in the residual stress generated by the pole piece. The higher the pressure, the greater the residual stress, which leads to physical storage expansion, a full electric state, and an increase in the expansion rate of the empty electric state.
The expansion of the anode leads to the deformation of the coil core, which affects the lithium intercalation degree and Li + diffusion rate of the negative electrode, thus seriously affecting the cycle performance of the battery.
Bloating caused by lithium battery gas production
The gas produced in the battery is another important cause of battery swelling. Dependent on whether the battery is in a normal temperature cycle, high-temperature cycle, or high-temperature shelving, it will produce different degrees of swelling and gas production.
According to the current research results, cell bloating is essentially caused by the decomposition of electrolytes. There are two cases of electrolyte decomposition: one is that there are impurities in the electrolyte, such as moisture and metal impurities, which cause the electrolyte to decompose and produce gas. The other is that the electrochemical window of the electrolyte is too low, which causes decomposition during the charging process.
After a lithium battery is assembled, a small amount of gas is generated during the pre-formation process. These gases are inevitable and are also the source of irreversible capacity loss of the battery.
During the first charging and discharging process, the electrons from the external circuit to the negative electrode react with the electrolyte on the surface of the negative electrode to generate the gas. During this process, the SEI is formed on the surface of the graphite negative electrode. As the thickness of the SEI increases, electrons cannot penetrate and inhibit the continuous oxidation and decomposition of the electrolyte.
When a battery is used, the internal gas production gradually increases due to the presence of impurities in the electrolyte or excessive moisture in the battery. These impurities in the electrolytes need to be carefully removed. Inadequate moisture control may be caused by the electrolyte itself, improper battery packaging, moisture, or damage to the corners. Any overcharge and over-discharge, abuse, and internal short-circuiting will also accelerate the gas production rate of the battery and cause battery failure.
In different systems, the degree of battery swelling is different.
For instance, in the graphite anode system battery, the main causes of gas swelling are the SEI film formation, excessive moisture in the cell, abnormal chemical conversion process, poor packaging, etc.
In the lithium titanate anode system, battery swelling is more serious. In addition to the impurities and moisture in the electrolyte, lithium titanate cannot form an SEI film on its surface like a graphite-anode system battery to inhibit its reaction to the electrolyte.
https://himaxelectronics.com/wp-content/uploads/2021/01/Causes-of-Lithium-Battery-Swelling.jpg400800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2021-01-22 02:18:142024-04-29 01:23:06What Causes Lithium Batteries To Swell?
Want to know more about LiPo charging? Here we will present a few data that will be involved when charging a LiPo battery to help you better understand the charging of LiPo batteries.
LiPo battery charging voltage
The highest voltage of LiPo battery charging, I believe that the majority of mold friends can know this common sense.4.20V is the highest voltage of LiPo batteries, but with the development and improvement of technology, most of the current manufacturers LiPo batteries can safely reach 4.25V, and some top technology manufacturers can achieve 4.30V, the voltage of 4.30V is the highest voltage of the current technology. Because the charger for the polymer battery of our RC model is basically a set voltage of 4.20V, it can be charged according to 4.20V. If you use other methods to increase the maximum charging voltage (such as 4.35V), it will cause irreversible damage to the battery.
LiPo battery charging mode
All LiPo batteries are charged in constant current and constant voltage to meet the requirements of fullness.
First of all, to explain to you what is called constant current and constant voltage charging. As the name implies, it is charged in a constant voltage after constant current. For large household B6 or A6 or other chargers to charge the RC battery, you should first set the two parameters of charging current and S number. In fact, this is to set the constant current value and the constant voltage value of the constant current and constant voltage mode.
For example, the parameter set to “5A, 6S”, after starting the charger, under the control of the program, the charger will charge the battery with 5A current in the early stage, while sampling and monitoring the battery voltage, when the battery voltage is close to or arrives 4.2V, the charger will gradually reduce the charging current, until the voltage is kept at 4.2V and the current is less than the preset value, the charger is considered to be fully charged and stops automatically.
So what is the default value mentioned above? According to our actual measurement data of some chargers, this preset value is generally divided into two situations.
Some manufacturers set the preset value as 10% of the charging current. For example, if you choose 5A charging, when the current is lower than 500MA after constant voltage, the program determines that the preset value has been reached.
Fixed values. Some chargers, like the A6, have a preset charging value of 100MA, while others have a simple charging setting of 20MA. If you use your own 4.2v power supply, you can make the charger smaller without limit.
This indicates that the smaller the present value is, the more the battery will be able to charge up to nearly 4.2v, the higher the battery will be fully charged.
LiPo batteries charging current
Talk about the charging current of the LiPo battery. Battery charging is actually a process of converting electrical energy into chemical energy, which is a chemical reaction. As we all learned in school, the intensity of a chemical reaction is strongly related to temperature and pressure. The speed of charge and discharge is actually the speed of chemical reaction. Conditional RC enthusiasts can find the relevant substances to do the experiment by yourself. The reaction speed is quite slow.
According to the experimental data and theoretical proof, lithium battery charging current within 1C without any damage to the battery. More than 2C current will cause a slight drop in capacity, while 5C charging will have a significant decrease in capacity. The reduction in capacity is mainly due to the damage caused by the crystallization of materials inside the battery, but after dozens of times, you will know that the battery capacity decreases and this is irreversible. Therefore, it is suggested that the model friend honestly control the charging current within 1C, which is better for the battery.
https://himaxelectronics.com/wp-content/uploads/2020/04/2.jpg427800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2021-01-05 03:15:102024-04-26 08:52:06LiPo Battery Best Charging Practices
As the largest countries of lithium polymer battery all over the world, China accounts for more than one-third of global production. Currently, strong demand for materials spreads over more than 100 lithium battery manufacturers, said to their urgent plans for the mass output increase within 2 years.
lithium polymer batterycharacteristics
Compared to most lithium polymer batteries, the lithium polymer battery is with characteristics as below:
1. No battery leakage problem
The battery does not contain a liquid electrolyte, using a colloidal solid.
2. Thin battery
Thin battery with a capacity of 3.6V400mAh, its thickness can be as thin as 0.45mm. Various Shapes
3. various shapes
The battery can be designed in various shapes: round, D, arc, etc.
4. Bending deformation
The battery can be bending deformation: polymer battery maximum bending around 90 °.
5. Single high voltage
liquid electrolyte battery can only get high voltage by several batteries in series, while polymer battery can be made into multi-layer combination in a single battery to achieve high voltage because there is no liquid itself.
6. High capacity
The capacity will be twice that of a lithium-ion battery of the same size.
Lithium polymer battery structure
No matter what kind of lithium polymer battery it is, the basic structure is a positive plate, negative plate, positive and negative current collector, diaphragm paper, shell and sealing ring, cover plate, etc.
1. Cathode material
Currently, the cathode material used is LiCoO2, LiMn2O4, LiFePO4, and doping modification systems of these materials. Cathode electrode sheet current collector is made of aluminum foil.
2. Anode material
various types of graphite. Anode material electrode sheet current collector is made of copper foil.
3. Electrolyte
At present, the lithium salt electrolyte is preferably to be LiPF6, but the price is relatively expensive; the other options like LiAsF6 with high toxicity, LiClO4 with strong oxidizing property and the organic solvent including DEC, DMC, DME, etc.
4. Diaphragm paper
The diaphragm adopts microporous polypropylene film or the special treated for low-density polyethylene film.
In addition, the shell, the cap, the seal and so on are changed depending on the shape of the battery along with the consideration of safety devices, protection circuits, etc.
The main processes in the lithium polymer battery manufacturing process are batching (pulping), Battery slices formation (coating), assembly and formation.
Among the above, the cathode electrode slurry is composed of cathode electrode active material lithium cobaltate (LiCoO 2 ), conductive agent (carbon powder, graphite, etc.), and binder PVdF (N-dimethyl pyrrolidone). Also, the anode electrode slurry is composed of the anode active material carbon or graphite and the binder PVdF(N-dimethyl arsenic alone).
The substrate of the cathode electrode is an aluminum foil and the substrate of the anode electrode is a copper foil.
The electrolyte to be injected is a multi-element organic substance such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl ester (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC). ), dimethyl glycol (DME), tetrahydrofuran (THF), and so on.
Since the coating & battery slices formation process generally uses mechanical wet hanging and drying, dust is less likely to be generated. But dust is generated during slicing and winding assembly. The main pollutant is the organic waste gas produced in the drying process.
https://himaxelectronics.com/wp-content/uploads/2020/06/LiPO-Battery.jpg400800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2021-01-05 03:11:012024-04-26 08:45:18How Lithium Polymer Batteries Are Made?
As Huawei and Samsung released the folding screen phones Mate X and Galaxy Fold respectively, they have a technologically-sense design and excellent hardware configuration. The unfolded area of the new folding screen mobile phone screen can reach more than 7.3 inches, which enhances the user experience. But in fact, a more disruptive, practical, and cost-effective mobile phone design is already on the way to development. It is a fully flexible wearable mobile phone.
Fully flexible mobile phones are dubbed “wrist phones” by the media. They are not limited to the folding of the middle part. They can bend the whole mobile phone freely, which is convenient to wear on the wrist and other parts to achieve better integration with the human body. The current folding screen mobile phones still use ordinary rigid batteries, avoiding the problem of using flexible batteries. If you want to introduce revolutionary fully flexible electronic devices, you must develop corresponding flexible power supplies and implant them. Therefore, the development of flexible lithium batteries with high energy density will be of great significance to promote the development of wearable flexible electronic devices.
The ideal flexible battery should have high flexibility, energy density, and power density at the same time. However, these factors often hinder each other in the flexible battery. In this review, this article made a detailed analysis based on the structural design of the battery components and the overall device level, and reviewed the latest developments in flexible lithium batteries, and summarized the current academic development ideas into the following four strategies:
1) Development of a deformable battery module with a porous structure
Such as porous current collectors, porous electrodes, flexible solid electrolytes, etc. Flexible porous structures are currently widely used in battery modules to cushion the strain generated when the battery device is subjected to bending and twisting.
a) A conductive porous film of graphene oxide, which has a conductivity as high as 3112 S/cm. The flexible lithium battery assembled with this film as the current collector did not find a significant decrease in capacity after 100 cycles of high charge-discharge rate (5C).
b) A composite cathode material of single-walled carbon nanotubes and polymer (2,5-dihydroxy-1,1-benzoquinone sulfide) is used to assemble flexible lithium batteries. The flexible battery exhibits a specific discharge capacity of 182 mAh/g at low current (50 mA/g), and can still reach a specific capacity of 75 mAh/g when discharged at a large current (5000 mA/g).
c) Using bacterial cellulose as a template, develop a solid electrolyte composite of Li7La3Zr2O12 (LLZO) and polyethylene oxide. The porous interconnected polymer matrix is used as a mechanical carrier that is soft and strong, and the LLZO particles used to transport Li-ions are embedded in it. The overall display shows a high ionic conductivity of 1.12×10-4 S/cm and excellent mechanical flexibility.
2) Ultra-thin battery design
Such as single-pair (or double-pair) positive/separator/negative structure. Compared with strategy 1, strategy 2 (ultra-thin battery design) requires battery design from the overall device level.
a) The ultra-thin flexible lithium battery with a thickness of only 0.4mm released by Himax Battery can be applied to various wearable devices. Even after bending with a bending radius of 25 mm, or twisting to an angle of ±25 degrees for more than 1,000 times, this flexible battery can still maintain 99% of the capacity.
b) A Li4Ti5O12/LiPON/Li thin-film solid-state battery prepared based on the flame spray pyrolysis method with flexible polyimide as the supporting substrate. After charging and discharging at a rate of 1C and cycling in a flat, bent, and flatform for 90 times, the battery’s discharge capacity retention rate is still as high as 98%, showing excellent cycle performance.
3) Geometric topology battery design
Such as linear structure, Origami, Kirigami structure, etc. In addition to improving the flexibility of the battery component material itself, the battery structure designed by the principle of geometric topology can reduce the stress change generated in the battery during the deformation process.
a. This strategy was first reported in the work of its linear battery. The flexible battery can not only adapt to bending deformation, but also more complex shape changes, such as folding and twisting.
b. Using spring-like LiCoO2/reduced graphene oxide as the positive electrode material, combined with gel electrolyte, a self-healing flexible lithium battery was designed and assembled. Under complex deformation (bending and torsion), charging and discharging at a current density of 1 A/g, the battery can still maintain a discharge specific capacity of 82.6 mAh/g; even if the battery is cut and healed five times, the battery can still be The specific discharge capacity is 50.1 mAh/g.
c. In addition to linear structures, paper folding technology is also widely used in flexible batteries. With the Origami origami solution, a two-dimensional sheet material can be folded along a predetermined crease to create a compact and deformable three-dimensional structure that can withstand high-strength deformation.
d. Soon after, a Kirigami scheme was developed combining folding and cutting technology. After 100 charge-discharge cycles, the battery can achieve a capacity retention rate of more than 85% and a coulombic efficiency of 8%. After 3,000 battery deformations, the maximum output power of the battery has not been significantly reduced.
4) Decouple the flexible and energy storage parts of the battery
Such as spine battery, Zigzag battery, etc. For the above-mentioned flexible battery design, dislocation, peeling, and shedding between the active material and the current collector still occur during the complex deformation process. The increased overpotential and internal resistance of the battery due to poor contact will reduce the capacity retention rate and coulomb efficiency of the full battery, which is not conducive to the cycle performance of the battery. The potential solution is to redesign the battery architecture to separate energy storage and provide flexibility.
a. De Volder et al. demonstrated a layered tapered carbon nanotube structure, similar to the morning glory of a plant. The wide corolla is used to carry the positive and negative active material particles, and the slender stem part and the current collector are below. The parts are tightly combined. During the deformation of the battery, most of the stress is applied to the current collector itself, and the tapered structure hardly produces strain during this period, thus exhibiting extremely high flexibility. The Fe2O3/LiNi8Co0.2O2 full battery assembled with this tapered structure can be charged and discharged 500 times at a rate of 1C and still has a capacity retention rate of 88%.
b. Inspired by the good mechanical strength and flexibility of the animal spine, a method for large-scale production of high-energy-density flexible lithium-ion batteries: store energy by surrounding thick, rigid parts in the axial direction (corresponding to the spine), And the thin, non-circular flexible part (corresponding to the bone marrow and intervertebral disc) is used to connect the “spine”, thereby achieving good flexibility and high energy density of the entire device. Since the volume of the rigid electrode part is much larger than the flexible connection part, occupying more than 95% of the volume of the battery cell, the energy density of the whole battery can reach 242Wh/L. The reasonable bionic design makes it pass the strong dynamic mechanical load test.
Questions and answers from flexible lithium battery experts
Xie Ming, a well-known flexible lithium battery expert in the industry, accepted an exclusive interview from the material man. The following is the interview content.
Q: Based on the actual situation of current industrial production, please comment on the four flexible lithium battery development strategies summarized in the review.
A: 1) Development of flexible battery elements with porous structure carbon (nanotube) paper is used as a flexible current collector, the cost is relatively high, which is not easily accepted by manufacturers; secondly, when carbon paper is used as a negative current collector, its side reactions are very obvious. If a porous metal current collector (such as copper mesh, aluminum mesh, etc.) is used, its flexibility can meet actual needs, but during the coating process, the slurry easily penetrates from the mesh pores. The current development of related coating processes is still An important challenge facing the corporate world.
2) Ultra-thin battery design
In order to achieve stable mechanical flexibility and electrochemical performance, ultra-thin batteries mostly use single-pair (or double-pair) low-capacity (usually less than 60 mAh) design, so their application scenarios and markets are very limited. In order to make the battery thinner, GREPOW has introduced a mature technology ultra-thin battery. While meeting the actual requirements, the overall battery thickness can be less than 8mm, and the thinnest can reach 0.4mm. You can imagine this is like A battery as thin as paper.
3) Geometric topology battery design
The concept proposed by this strategy is very good, represented by the linear battery, its mechanical flexibility, and electrochemical performance can be guaranteed. At present, many research teams are committed to developing new types of fibrous and linear batteries to solve traditional bottlenecks. The fly in the ointment is that the positive electrode, negative electrode, and separator of this linear battery rely on self-synthesis, which is different from commercial battery components, which will increase production costs. In addition, most linear batteries use heat-shrinkable tubes instead of aluminum-plastic film packaging. The heat-shrinkable tube materials have a limited barrier to water vapor and oxygen, and it is difficult to meet actual needs in long-term use.
4) Decouple the flexible and energy storage parts of the battery
This strategy uses improved commercial battery components, which is of great significance to promote the development and production of flexible lithium batteries. As early as 14 years or so, some Chinese companies have begun to develop “bamboo-shaped” batteries that look similar to “spine” batteries. According to the latest literature report on “Zigzag” batteries, the energy density of flexible lithium batteries assembled with the “decoupling” strategy can reach 275 Wh/L. After the process optimization of industrial standards, the energy density can still be achieved. Room for improvement. At present, an MIT research group has developed a series of fully automatic and personalized battery pole piece winding equipment. It is believed that with the intervention of an intelligent manufacturing system (IMS) service providers, the shortcomings of this type of battery assembly process can be gradually overcome.
Q: Could you please introduce the application scenarios of flexible batteries in the future?
A: At present, flexible wearable devices are the largest application market for flexible batteries. Taking smartwatches as an example, many large consumer electronics manufacturers have proposed the idea of implanting flexible batteries into smartwatch straps, removing the battery from the panel, and realizing an ultra-light and ultra-thin dial design. They hope that the capacity of the flexible battery can be close to 500 mAh, but the volume energy density of the more mature flexible lithium battery samples in the industry is about 300-400 Wh/L, which is temporarily difficult to achieve the above goal. In addition, in order to introduce the current in the watchband to the dial, it is necessary to design the circuit in the watchband, which will be a considerable investment in development.
In addition, fully flexible mobile phones will be an important application scenario for flexible lithium batteries in the future. A few days ago, Samsung released a new foldable mobile phone Galaxy Fold, but this phone still uses ordinary rigid batteries, avoiding the problem of using flexible batteries. If you want to launch a revolutionary fully flexible mobile phone, you must develop a high-capacity (more than 2000 mAh) flexible battery implanted in it. As mentioned in this review, energy density and mechanical flexibility are usually in a flexible battery. The combination of scientific experiments and theoretical simulation is used to deeply study the basic mechanical problems in flexible batteries. Development work is very helpful.
Q: Please talk about the core competitiveness of flexible batteries from the perspective of industrial applications.
A: Compared with traditional non-bendable batteries, the volumetric energy density of flexible batteries will definitely be affected. Therefore, flexible batteries must find their own application positioning, that is, place batteries in places where batteries could not be placed before, make full use of every effective space of electronic devices, and increase the standby time by increasing the overall battery capacity of electronic devices. This is another strategy to solve consumers’ anxiety about mobile phone standby when the energy density of lithium-ion battery materials has not been greatly developed.
In short, flexible batteries do have a broad potential application market. In recent years, well-known international companies such as Apple and Samsung have launched patent arrangements in related fields. However, most downstream electronic equipment manufacturers still expect to start the development of a fully flexible series of products after the flexible battery production technology has matured.
If you are interested in our products, please don’t hesitate to contact us at any time!
Introduce you to the factors that cause lithium-polymer batteries to fail and how to prevent them from failure. Some approaches that can maximize lipo batteries’ life will also be included.
Cycle life
Generally speaking, the standard service life of a lithium polymer battery is 3 years, and the number of cycles ranges from 300-500. The cycle life of a battery does not mean that the battery will be completely unusable at the end of that number but that the discharge efficiency and capacity of the battery will be reduced accordingly. The range for the number of cycles usually refers to the battery’s capacity retention of 80%. Improper usage may result in a reduced cycle life, thus resulting in a premature battery failure.
Self-discharge
Lithium batteries will naturally undergo self-discharge from the moment they’re produced regardless of whether they are being stored, transported, or connected to a device. Thus, it’s very important to ensure that the battery is checked and cycled every three months to prevent any deep discharges. Once a battery has been discharged beyond its standard voltage platform, it’ll be impossible to recover without damaging the internals, resulting in premature battery failure from over discharging.
Overcharging
Another factor of premature failure is overcharging. Overcharging may cause a battery to swell or even catch on fire. A typical lithium battery has a fully charged voltage of 4.2V unless it’s a specially formulated Lithium High-Voltage battery that is otherwise known as LiHv. Fun fact: Grepow’s High Voltage batteries can produce batteries that charge up to 4.45V without causing damage to the battery’s cycle life.
The BMS, is a great way to prevent overcharging and overdischarging thus preventing possible premature battery failure.
Inappropriate temperature
Utilizing a battery at inappropriate temperatures is another factor that could cause premature battery failure. Under low temperatures, the chemical reactions within the battery become sluggish, which results in plating. Under high temperatures, the electrolytes will have difficulty maintaining their liquid form causing evaporation and ultimately making the battery short circuit.
Violent damage
As always, drops and punctures to a battery can undoubtedly damage it. Avoiding the undesirable factors mentioned here will allow you to fully maximize the potential and lifespan of a Lithium Polymer battery.
https://himaxelectronics.com/wp-content/uploads/2020/12/QQ图片20191209154635-scaled.jpg19202560administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2020-12-22 10:50:572024-04-26 06:28:12Factors That May Cause Premature Lithium-polymer Battery Failures
The shell materials used in lithium batteries on the market can be roughly divided into three types: steel shell, aluminum shell and pouch cell (i.e. aluminum plastic film, soft pack). We will explore the characteristics, applications and differences between them in this article.
Steel–Shell Battery
The steel material for this battery is physically stable with its stress resistance higher than aluminum shell material. It is mostly used as the shell material of cylindrical lithium batteries.
In order to prevent oxidation of the steel battery’s positive electrode active material, manufacturers usually use nickel plating to protect the iron matrix of the steel shell and place a safety device inside the battery cell.
At present, most laptops use steel-shell batteries, but it is also used in toy models and power tools.
Aluminum–Shell Battery
The aluminum shell is a battery shell made of aluminum alloy material. It is mainly used in square lithium batteries. They are environmentally friendly and lighter than steel while having strong plasticity and stable chemical properties.
Generally, the material of the aluminum shell is aluminum-manganese alloy, and its main alloy components are Mn, Cu, Mg, Si, and Fe. These five alloys play different roles in the aluminum shell battery. For example, Cu and Mg improve strength and hardness, Mn improves corrosion resistance, Si can enhance the heat treatment effect of magnesium-containing aluminum alloys, and Fe can improve high temperature strength.
Aluminum shell batteries are the main shell material of liquid lithium batteries, which is used in almost all areas involved.
The pouch-cell battery (soft pack battery) is a liquid lithium-ion battery covered with a polymer shell. The biggest difference from other batteries is its packaging material, aluminum plastic film, which is also the most important and technically difficult material in pouch cells.
The packaging materials are usually divided into three layers: the outer barrier layer (it is usually an outer protective layer composed of nylon BOPA or PET), barrier layer (middle layer aluminum foil) and inner layer (multifunctional high barrier layer). The materials such as positive electrode, negative electrode, electrolyte, separator and so on are similar to other types of batteries.
The hidden danger of lithium batteries is the instability of the material or other unexpected comprehensive factors, which may cause the heat to run out of control and result in gas accumulation in the battery. This is dangerous because steel-shell and aluminum-shell batteries have a fixed space. When the gas inside these batteries expands beyond the limits of this space, the battery will explode. Pouch cells will also bulge up and crack, so they have a higher safety index.
Compared with steel and aluminum batteries (i.e. hard-shell batteries), pouch-cell batteries can have a flexible design, low internal resistance, more cycle time, and high energy density. They are lightweight, and they do not explode easily.
Pouch-cell batteries are 40% lighter than steel-shell lithium batteries of the same capacity and 20% lighter than aluminum-shell batteries. The capacity can be 10-15% higher than steel-shell batteries of the same size and 5-10% higher than aluminum-shell batteries of the same size.
In light of the advantages of pouch-cell batteries, industry experts predict that pouch-cell batteries will have a higher chance of penetrating the new energy vehicle market with more development. In the future, pouch-cell batteries are expected to account for more than 50% of all types of batteries.
In addition to being used as power batteries and energy storage batteries, pouch-cell batteries are also used as battery components for 3C electronic products, such as mobile phones, drones, wearable devices, RCs, etc.
https://himaxelectronics.com/wp-content/uploads/2020/11/Structure-of-Steel.jpg400800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2020-11-10 03:54:562024-04-29 01:30:42The Difference Between Steel-shell, Aluminum-shell And Pouch-cell Batteries
Aerial photography enthusiasts try to shoot on sunny summer days, but flying under high temperatures for a long time can be a strain for their drones. Continuous flying under higher temperatures can easily cause serious heating of the equipment and may even cause battery failure or explosion and permanent damage to the drone’s equipment.
Factors that affect the work of drones in high temperature
Most drones use lithium polymer batteries, which generate electricity through chemical reactions. High temperatures affect the rate of chemical reactions, which undoubtedly shortens the flight time and life of the battery.
In sweltering temperatures, the air can be thicker. The thicker hot air forces the propellers and motors to work harder to keep the drone in the air and contributes to shorter flight time.
In some cases, once the battery heats up, it will gradually expand as time goes by while slowly emitting chemical substances and toxic smoke. The heat generated may also overheat the electronic equipment or melt wires and plastics.
Definitely take temperatures into account when you want to fly your drone. You can download free apps, like UAV Forecast, to help you make informed decisions before you fly.
We will explore some tips below if you decide to fly your drone in hot temperatures.
When flying a drone in hot weather, pay attention to certain factors
When switching out batteries, wait for the drone to cool down a bit, and take longer breaks between flights.
Reduce jerking your drone around or making sudden turns or stops during flight because high temperature will affect the discharge capacity of the battery and may shorten the service life of the drone. In short, try to have a smooth flight.
Drones should indicate the operating temperature in their manuals, and it is best not to exceed a certain timeframe for flying under extreme temperatures. Here is a list of the operating temperatures of several drones for you to refer to:
The batteries must be fully charged and placed in a cool place before flying. Do not leave your electronics under direct sunlight.
If your drone is running hot after the flight, place it in a cool place to dissipate heat before storage.
https://himaxelectronics.com/wp-content/uploads/2020/10/High-Temperatures-Lipo-Battery.jpg400800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2020-10-20 03:25:402024-04-26 03:51:00Using Drones Under High Temperatures
You may have heard that there are restrictions when flying your drone in high temperatures, but did you know that it’s a similar case in low temperatures too?
We will explore some factors to consider if you plan on flying your drone in cold weather.
The impact of low temperatures on drones
Lower temperatures slow down the chemical reaction of LiPo (lithium-ion polymer) batteries, thereby reducing battery capacity, increasing resistance, and shortening the flight time. Drone manufacturer DJI states on its website that the LiPo batteries that power their drones start draining at an increased rate at temperatures below 59℉ (15°C).
It’s important that users read the manuals for their drones before a flight. The operator temperature of most drones is set at 32 to 104 ℉ (0 to 40°C), so you should avoid flying outside of this temperature range.
To fly a drone in low-temperature, you need to prepare in all aspects.
Measure
Before going out
Plan your day out beforehand and try to finish your flight as soon as possible before it gets too dark. See the weather forecast: if there’s snow, hail, or rain, reschedule your flight as these weather conditions can damage your equipment and drones and very likely cause a crash.
Ensure your batteries are fully charged and have spare ones on hand to switch out.
When going out
Limit direct exposure of your batteries to the cold air. Keep them in their gear or protective equipment instead of just in the trunk of your vehicle.
Take off
When launching your drone, raise the aircraft 10-20 feet from the ground and make it hover for 30-60 seconds. This can increase the temperature of the battery to achieve a warm-up effect. Some apps, such as the DJI GO, allow you to check and monitor the battery temperature.
Source: DJI
Focus on the battery’s voltage. You should keep the battery’s voltage indicator displayed on your monitor so you can keep track of it.
Check the components. In a cold environment, some parts, like propellers, become more fragile. Therefore, it is necessary to check them more diligently for cracks or damage. You can also consider replacing them with solid carbon fiber blades.
Avoid running out of capacity. Fly until the battery drops to 30-40% of its capacity, and then bring the drone back down. In order to prevent other unpredictable situations from happening, don’t drain your battery completely when flying.
Stop flying immediately if it starts to rain or snow. Be careful because most drones are not waterproof. Moisture may short-circuit the motor and cause the drone or controller to malfunction.
For you
Don’t forget to keep yourself warm. It is best to wear gloves which can touch the screen because it will be very inconvenient to operate the device with cold and stiff hands.
Wear goggles. When flying in icy or snow-covered weather, your eyes may be damaged due to the greater light reflection. Goggles can avoid this problem.
https://himaxelectronics.com/wp-content/uploads/2020/10/Drone-Battery-lipo.jpg400800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2020-10-20 03:20:272024-04-26 03:50:38Can I Fly My Drone In The Winter?
Low-temperature lithium-ion batteries mainly include low-temperature lithium-ion polymer (LiPo) batteries, low-temperature 18650 batteries, and low-temperature lithium iron phosphate (LiPO4) batteries. We will explore the advantages and disadvantages of each one.
Low-temperature lithium polymer batteries
Low-temperature LiPo batteries have the best low-temperature performance especially in smart wearable devices, where the advantages are more prominent.
Performance characteristics
Himax’s LiPo batteries can be made to operate in environments with low-temperatures of -50℃ to 50℃. Under low-temperatures, the batteries can achieve a lower internal resistance and, thus, a high discharge rate. Compared with traditional lithium polymer batteries, Himax’s batteries have broken through the discharge temperature limits of -20℃ to 60℃.
They are able to discharge over 60% efficiency at 0.2C at -40℃ and discharge over 80% efficiency at 0.2C at -30℃. When charged at 20℃ to 30℃ by 0.2C, the capacity can maintain above 85% after 300 cycles. The batteries can be ready for mass production, and they have been widely used in cold climates and military products.
Shape advantage
With stacking technology, battery shapes can be widely customized, which allows for more flexibility and space within products. We can also create small and ultra-thin batteries with low-temperature characteristics used in special fields or professional smart equipment.
Weight advantage
Under the same voltage and capacity conditions, low-temperature lithium-ion polymer batteries and low-temperature lithium iron phosphate batteries are lighter than low-temperature 18650 batteries. However, LiPo batteries are the most expensive in terms of production and manufacturing costs, which is one of the important factors limiting its use in some application areas.
Low-temperature 18650 lithium-ion batteries
Low-temperature 18650 lithium-ion batteries mainly consist of liquid electrolytes. these cylindrical batteries with steel shells have fixed dimensions, which means that their shape and size are fixed as well. The largest capacity is currently 3300mAh, which can only be achieved by a limited number of manufacturers.
Characteristics
At temperatures between -40℃ to 60℃, the effective discharge capacity is 40% to 55%, and the effective cycle life is more than 180 cycles. At temperatures between -30℃ to 65℃ at 0.2C discharge, the effective discharge capacity is above 65%. At 1C rate discharge, the discharge capacity is above 60%, and the cycle life comes out to more than 200 cycles.
At temperatures between -20℃ to 75℃, the effective discharge capacity is more than 80%, and the cycle life is more than 300 cycles.
Due to the fixed performance and size of the battery, there is limited use for this battery, but its production and manufacturing costs are relatively low.
Low-temperature lithium iron phosphate batteries
Low-temperature LiPO4 batteries have two kinds of packaging cases
one is a steel case, which is currently mostly used in new energy batteries, such as energy-storage batteries and new energy vehicle batteries. The other is a soft-pack LiPO4 battery with aluminum plastic film for the outer packaging.
The performance of this battery is basically the same as that of the LiPo battery.
However, the low-temperature performance of LiPo batteries is better than that of 18650 batteries. The development of LiPO4-battery technology has not been long, and the requirements for production equipment are relatively high.
LiPO batteries often abbreviated as Lithium polymer batteries are rechargeable batteries that use polymer electrolytes instead of liquid electrolytes. RC cars are the popular market of LiPo batteries, you will be needing batteries for running them and LiPo batteries are the best option. They are best known for maintaining a steady voltage, surpassing all its other competitors.
What is the Best LiPo Battery for RC Cars?
All batteries are the same and identical, but that’s not true. They may look identical and share the same capabilities and compatibilities but they are different, in terms of quality and performance. Choosing the right one for your battery can be a task but here we are with guidelines that will help you in opting for the best one.
The best tip is that do your research and testing before the purchasing. Different brands will have different price tags and you must be ready to invest some money in buying them. Don’t buy a cheaper one that can later be heavy on your pocket but don’t buy an expensive one either. Some brands with low prices also offer good quality batteries that will last you longer than the expensive ones. So, the cost cannot determine the quality of the battery but its performance does. Make sure to do independent testing, consider battery configuration, and check the connectors as well. Also, make sure to check the reviews.
How Long Does a LiPo Battery for RC Cars Last?
LiPo batteries come with a lot of advantages but it has a shorter lifespan if compared to the nickel batteries. A LiPo battery may last typically fr about 150-300 cycles that totally depends on how it is cared for. Just when you will start using your battery frequently, charging and discharging it, it will ultimately be losing its capacity. You take your battery of 1300 mAH out of the box, but it will drop up to 75%, meaning about 1000 mAH.
A 1000 mAH battery bearing a load of 500 mAH will last for about 2 hours. Similarly, if your load is 2000 mAH then it would only last for 30 minutes. A 5000 mAH battery is quoted to last for about 20-25 minutes depending on the driving speed and your driving habits.
However, there are several methods that you can do for making our battery last longer. It includes the usage of proper charge voltage and balanced charging. Do, all the things that are necessary for maintaining the LiPo batteries for RC cars and you will definitely be treated with good and satisfactory outcomes.
How do you Care for your LiPo Battery for RC Cars?
Generally, good care and maintenance are required for LiPo batteries as they are a little too sensitive demanding some extra attention and care. But you can just ignore them for the fact that they need care because they are giving you a bundle of pros as well, including the lighter weight, higher capacities, higher discharge rates, and much more.
Here are some of the tips that will lead you to a better performance of LiPo batteries of RC cars.
Compatible Charger
Not just for increasing the lifespan, compatible chargers for LiPo batteries are the first thing that should be taken care of. If you are using a non-compatible charger you are not fully charging your battery, increasing the safety risks, and also contributing to shortening the life of the battery.
Effective Charging
It is advised to not over-discharge your battery and store the battery fully charged. do not overcharge your battery past 4.2 V per cell. Using a compatible charger will also help you in keeping the voltage and current same until it reaches the peak. Make sure to charge it as per instructions. Don’t charge them at below freezing point or near the flammable surfaces. Also, ensure that your battery is not damaged, broken, or swollen.
Discharging
Do not discharge your batteries more than amperage rates specified on the labels. Discharging the battery low than 3V can lead you to some consequences. Also, ensure that your battery doesn’t exceed the temperature of 140F during the discharging process.
Storage
Extra Care and attention are needed even in the storage of LiPo batteries. If you are storing your battery fr more than 30 days or planning to leave it as it is for a month or so, do not leave your battery fully charged. Make sure that you are not storing loose batteries together. It’s also recommended that you should not store your battery at extreme temperatures, near the flammable surfaces or in the direct sunlight. Always disconnect the batteries that are not in use and store them in a non-conductive fireproof container as it is really necessary to prevent any unwanted consequences. Improper storage is the most common problem that occurs with LiPo batteries.
Disposal
It’s really important to dispose of the LiPo battery properly as it can be a hazard. If you are having a bad day with LiPo batteries then dispose of them in the bins after completely discharging them, and checking the voltage of them. Place the LiPo in a saltwater bath and it will short out the battery, then check the voltage and then dispose them of.
General Care
Don’t disassemble the cells, never dispose of them in fire or use them near flammable surfaces, avoiding the opening and deforming of the cell, avoiding them to not get hit or bend or striking them with sharp edges are a part of some general care that should be don while handling the LiPo batteries for RC cars. You can also use a fire-resistant container to keep your batteries and yourself safe and sound.
https://himaxelectronics.com/wp-content/uploads/2020/07/rc-car-battery-1.jpg480800administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2020-07-15 03:21:412024-04-26 06:25:24RC Car Batteries: Introduction, Cycle Life, and Care
