There are many devices that use batteries in our daily life, so what shapes do you know?Batteries, of course, that’s rechargeable lithium-ion batteries and as we all know, lead-acid batteries (usually standard size) are usually standard size, but lithium-ion batteries can come in a variety of packages and shape battery.
Custom Shape Battery
One of the most common misconceptions is that polymer batteries are different.In fact, they are one of the most common types of lithium-ion batteries, assembled and packaged in flat, bag-like shapes.Their core design is based on standard lithium ion chemistry. They are called “polymer” batteries because they tend to use gel-like rather than liquid-like electrolytes. The outer packing is thin foil that holds the inner structure together.As a result, they can be easily damaged or punctured, and are often (if not always embedded in mobile devices) protected mechanically.
One of the advantages of polymer batteries is that they can be manufactured in almost any custom size or shape.This ability to make batteries suitable for mobile devices, not vice versa, makes polymer batteries extremely attractive.Polymer batteries can also be made very thin.This photo shows a polymer battery made by GREPOW for smart CARDS.It’s only about 0.4 millimeters thick.The drawback of polymer batteries is the lack of standardization, which makes them expensive.Each battery model must be designed and shaped to a specific size for a mobile device manufacturer.Polymer batteries cost nearly twice as much (for the same amount of stored energy) as comparable standard 18650 batteries.
18650 Battery
The naming of the 18650 battery is hardly creative.It was a standard cylinder 18mm in diameter and 65mm in height, hence the name.Over the past decade, the standard size of these batteries has made them ubiquitous and cheap.They are widely used in laptops, but they have proved less practical for thin smartphones.Tesla motors took advantage of mass production and the low cost of the 18650 to use in electric vehicles.The Tesla Model S’s battery pack contains nearly 7,000 such cells.Panasonic’s 18650 battery has a capacity of 3,400 mAh.It’s similar to the ones used in tesla cars.Other major makers of electric cars have opted for large-size polymer batteries. Still, there are 18650.
Prismatic Shape Battery
The third type of battery is called prismatic.They are very similar in nature to polymer batteries, but are packaged in solid casings or tanks usually made of aluminium alloy.This provides additional mechanical protection and necessary safety.Mobile devices that offer replaceable batteries use square batteries.Prismatic cells tend to be thicker than polymer cells because of the walls of the external tank.
Keen readers may ask questions about the connector to the SONY polymer battery.In fact, it’s an electrical connector made from thin, flexible cables.At the tip of this cable, you can observe some of the circuits that provide the necessary electronic protection for the battery.In particular, the circuit ensures that the battery is not subjected to excessive voltages or currents.If the battery is exposed to adverse conditions, the built-in fuse disconnects the battery.Similar circuits are embedded inside prismatic cells.However, the 18650 battery is bare, that is, it does not include any such protection circuit, which must be included in the external battery management system before the battery can be used.
Above is the battery knowledge that GREPOW shares with you. If you are interested in SHAPE BATTERY, want to learn more about different shapes battery information, please contact the Grepow office at info@grepow.com. More information can be found at https://www.grepow.com/
Perhaps someone has these misconceptions, customization just tailor design the compact size, and relatively higher cost. However, the existing battery product has more limitation, it is suitable for individual consumers and much enough to fulfill their needs. For industrial application, there are circumstances where a battery pack has to function in a very specific manner, conform to particular measurements or fulfill other highly precise requirements. In such instances a custom designed and built battery pack is often necessary.
So in this article, we discuss the advantages of customized battery with case study, something you need to notice, and how it creates value to your company.
The Four Advantages of Customized Battery:
Compact Size
Similar to most portable electronic devices, the battery of wearable devices are complicated, some specific requirements to the shape, size, durability, discharge rate, and other functions.
Of course, we (consumer) all wanted much light, handy, and durable electronic devices. Different types of battery and technology can reach more requirements for wearable devices.
Moreover, currently the most popular among wearable devices are lithium ion (Li-ion) and lithium ion polymer (LiPo, Li-Po, LIP, Li-poly) batteries, the small lithium ion polymer batteries or LiCoin rechargeable batteries are mostly used.
Wearable devices like wristband, smartwatches, smart ring, etc., which we often encounter every day, can customize the shape of the battery in order to optimize the space, size, and weight of the product. Curved Lipo battery in a Shaped Battery series.
The curved strip battery can be installed in a ring-shaped band, and it has some features of large capacity and low self-discharge, which enables it to maintain a longer performing time and solve the capacity problem of the wearable device.
In addition to the Curved Shape battery, the shapes currently developed are:
As we know, there are many smart glasses (like VR glasses) on the market, and various functions. In order to detect the user’s physical condition, such as the step counter, heart rate calculator and analysis of sleep quality, etc., most of these devices are equipped with different types of sensors, including accelerometers and gyroscopes. In order to allow users to see virtual images through the glasses, they install the image projected devices on the glasses, which also requires lots of electricity to support.
Secondly, in order to meet the design and its functions, the battery should also be designed in different shapes to fill in the space of product. Therefore, for battery manufacturers, customize the shape and size of the battery depends on their specific needs, and the precision of sculptures is continuously improved. Therefore, breaking through the boundaries of existing products may not be impossible.
Targeted Customization by needs
We have received a request from a customer to tailor-made the battery for medical used. Due to the special functions and environmental condition of their products, we provide the customization solution to them.
Why they need customization solution, because the battery required conduct discharge high current in a short period in a low-temperature environment, the cold outdoor environment near -30 to 40°C. Also, the battery must allow continuously output at 12V at -40°C, achieved a few seconds of 2.5A discharge with the protection of battery management system (BMS). The special requirement like that is cannot be met by existing battery products, so we need to work with engineers to tailor design this battery for them.
As we know, the battery performs in low-temperature will affect the discharge current and capacity, only a few kinds of batteries can be used in an extremely cold environment. Currently, most of the low-temperature battery products on the market can only be charged and discharged at about -20°C. Therefore, existing battery product’s specifications may not be able to conform to their products, and their sizes are also need customize, thus companies need to find battery company who have ability to produce the low temperature and high discharge cells for them.
Battery Cycling test at 0.2c charging and discharging at -20℃Battery test discharging at different temperature
In addition to temperature, what others can be customized? There are 6 features below:
Voltage
Capacity
Dimensions
Charge Current
Discharge Current
Usage Temperature
Keep secret
In terms of customized services, the customer’s requirements are related to their unique product design. Whatever the specifications, size and application areas of the battery, it is a business secret of customers. Therefore, most of its information will be strictly confidential and will not be disclosed until it is approved by the customer.
Reduce Cost
In this session, we divided as “Short-Term Cost” and “Lifetime Cost” these two parts.
At first, you might think that the price of a custom battery is higher, but it’s not entirely correct. There is various 3C product in the market, which have their own patent and design. Thus, the matching battery must be perfectly matched with the product. If there is a difference in shape or size, the company may have to adjust the design of the product to cater to the battery, thus modify or even redesign the product. In this way, the customized battery not only makes the product more versatile, but also increases the efficiency of launching new products and reduces the overall cost.
In addition to the purchase cost, there are some additional costs before and after the sale, such as battery design, R&D, after-sales transportation costs, technical support, and maintenance warranty, etc., are included in the considerations. Let say an international battery company, will cooperate with SME and local re-seller all over the world, which can closer to customer and provide support, so directly deliver batteries to customers is easier. It can be seen that the customization solution can reduce unnecessary costs from products and services, can concentrate resources on more competitive and valuable works.
If the purchased battery will be used for a long time, in terms of long-term cost, the life span of the battery, using cycle, the safety of storage, and the maintenance cost in the future should be considered in comparison with the cost of purchase.
Perhaps most of you have used or using lead-acid (LA) batteries. Lead-acid battery are mostly used in the field of energy storage due to its following features:
Low price
Raw materials are easy to explore
Stable performance
Easy to recycle
Suitable for high current discharge
The lower cost of materials thus the lower purchase cost, but its performance and life span are far less thanLiFePO4. At the same size comparison, the LiFePO4 battery has more capacity, longer life span, either of high temperature and low temperature resistance, safety and environmental friendly. Despite the higher upfront cost of LiFePO4 battery, but free of the maintenance cost, and cost of replacement. Let say we compare the total cost of ownership LiFePO4 battery, to three equivalent size off-the-shelf lead-acid battery technologies, in the long run, the average cycling cost of lithium iron phosphate battery is lower. And these savings make it more valuable than lead-acid batteries, making them more suitable for long-term investments.
Precautions of customization
Custom batteries are not suitable for everyone. As mentioned before, it may be better for individual consumers to purchase existing battery products directly, so there are some parts to be aware of before choosing a customized battery solution.
Which chemistry is more suitable for your product?
Not each chemistry provides the same performance in every application, and it’s important to determine which chemistry is best for your needs. As I mentioned before, Lead Acid (LA)Battery is economical but there are many complex long-term costs like the cost of replacement and maintenance.
As a result, battery companies have a significant role in this situation, providing specific battery solution for customized voltage or capacity you may need, and providing the right chemicals for your application.
Communication with the synergy effect
When you decide to customize the battery, the information provided is not comprehensive enough, it will not only affect the efficiency, but also the performance of the end product.
If customer requests, the customized battery can also be packaged. Most of the packaged batteries will be equipped with protective plates, wires, plug wires, housings, etc., and perhaps need to install FPC soft cable, some needs plastic shells, such as RC Car’s battery,and may need to add communication protocols, such as car batteries. Therefore, these product use polymer lithium batteries involving high current, shell and different color, etc.. Detailed expression of requirements and parameter requirements can reduce many unnecessary errors.
Does the company have a relative qualification for some specific application?
IATF16949
If you are work in the automotive industry, you might already know with this qualification. This is a special agency established in 1996 by the world’s leading automobile manufacturers and associations to coordinate the international automotive quality system specifications. The full name is the International Automotive Task Force (IATF), and the IATF 16949 technical standard. It is an international standard applied in the automotive industry to further standardize the requirements of the quality management system of various organizations in the automotive industry.
There are also some international certifications in the industry that are required for the internationalization of battery companies and for the production of high quality batteries.
ISO13845
ISO 13485 is the only globally recognized quality standard for medical devices, including the design, production, operation, monitoring, transportation, installation, and after-sales service of medical equipment. The terms of ISO 13485 are similar to the US FDA medical equipment management system CFR Part 820. In addition to improving the company’s medical equipment and process requirements, it is also a shortcut and entry condition for the company’s products to enter the international market.
The ISO13485 standard is developed to complement the ISO 9001 standard and covers the quality management and assurance systems of manufacturers and suppliers of medical products.
UL (UNDERWRITER LABORATORY)
This is a US safety certification. If you want to enter the US market, you will have to obtain this qualification to test the safety of the battery products. The detailed test content can be seen here.
CE (COMMUNATE EUROPIEA)
Indicates that the product meets the requirements of a series of European directives such as safety, hygiene, environmental protection and consumer protection. Confirm that the product has passed the corresponding conformity assessment procedure or the manufacturer’s declaration of conformity, which is the “passport” for the product to be allowed to enter the EU market.
UN38.3
This can be said to be the basic in the battery qualification certification, which is to ensure that the battery products through the high simulation, high and low temperature cycle, vibration test, impact test, 55°C external short circuit, impact test, overcharge test, forced discharge test, to ensure lithium Battery transportation is safe. If this test report is not available, civil aviation will ban lithium batteries for air transportation.
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This article is written by Grepow. If you want to learn more about battery, and customized battery, please visit our official website or blog to read more articles, or directly communicated with our specialists.
Since entering the market, lithium batteries have been widely used for their long life and large capacity with no memory. With the expansion of batteries in various applications and fields, many problems have risen: reduced capacity, severe voltage attenuation, fast life-cycle degradation, and lithium plating just to name a few.
For instance, the operating temperature of traditional lithium-ion batteries is between -20°C to 55° C. In aerospace, automotive, and military fields, these batteries must operate normally at -40° C. This becomes an issue when the discharge capacity of low-temperature lithium-ion batteries is only about 31.5% at room temperature.
1. Factors that limit the performance of low-temperature, lithium-ion batteries
There are several factors that restrict the performance of lithium-ion batteries in low-temperature environments.
The viscosity of the electrolytes in a battery increase in response to low temperatures, and the electrolytes can even solidify.
The compatibility between the electrolytes, negative electrodes, and the separator also deteriorates.
Severe precipitation occurs at the negative electrode of a lithium-ion battery. The precipitated lithium reacts with the electrolytes, and the deposition ultimately causes the SEI (Solid Electrolyte Interface) to increase in thickness.
The diffusion system of a lithium-ion battery inside the active material decreases, and the Rct (Charge Transfer Resistance) increases significantly.
All these factors serve to severely lower the performance of low-temperature, lithium-ion batteries.
2. The decisive factors that affect the low-temperature performance
(1)ELECTROLYTES
The electrolyte has the greatest impact on the low-temperature performance of lithium-ion batteries. This is in large part due to the effect of the composition and physical and chemical properties of the electrolyte.
As stated earlier, cycling a battery at low temperatures will cause the viscosity of the electrolytes in a battery to increase. In addition, the ion conduction speed will slow down, which ultimately causes the mismatch of the electromigration speed of the external circuit. This results in the polarization of the battery and the charge and the sharp decrease in capacity. The problem is further compounded when dendrites form on the surface of a negative electrode (this occurs easily when charging at low temperatures), which results in battery failure.
The low-temperature performance of electrolytes is closely related to the conductivity of electrolytes. An electrolyte with high conductivity can transfer ions quickly and can exhibit more capacity at low temperatures. The more the lithium salt dissociates in an electrolyte, the more the number of migrations and the higher the electrical conductivity. With a higher conductivity comes a faster ion conduction rate, smaller polarization, and better battery performance at low temperatures. Therefore, higher electrical conductivity is a necessary condition for achieving a high-performing, low-temperature lithium-ion battery.
One of the ways to improve the conductivity of an electrolyte is to reduce the viscosity of the solvent. The conductivity of the electrolyte is related to the composition of the electrolyte, and reducing the viscosity of the solvent is one of the ways to improve the conductivity of the electrolyte. The good fluidity of the solvent at low temperature is the guarantee of ion transport, and the solid electrolyte membrane formed by the electrolyte at the negative electrode at low temperature is also the key to affect lithium-ion conduction. RSEI (Resistant Solid Electrolyte Interface) is the main impedance of lithium-ion batteries in low-temperature environments.
(2) LI + DIFFUSION RESISTANCE
The other main factor limiting the low-temperature performance of lithium-ion batteries is the sharply increased Li + diffusion resistance at low temperatures, not the SEI film.
3. Low-temperature characteristics of different materials in lithium-ion batteries
LOW-TEMPERATURE CHARACTERISTICS OF LAYERED CATHODE MATERIALS
The layered structure of cathode materials has the unparalleled performance rate of a one-dimensional lithium-ion diffusion channel and the structural stability of a three-dimensional channel. It is the earliest commercially available lithium-ion battery cathode material. Its representative substances are LiCoO2, Li (Co1-xNix) O2, Li (Ni, Co, Mn) O2 and so on.
Experts took LiCoO2 / MCMB as the research object and tested its low-temperature charge and discharge characteristics.
The results show that as the temperature decreases, the discharge platform decreases from 3.762V (0 ° C) to 3.207V (-30 ° C); the total battery capacity also sharply decreases from 78.98mA · h (0 ° C) to 68.55mA · h (–30 ° C).
LOW-TEMPERATURE CHARACTERISTICS OF SPINEL ANODE MATERIALS
The spinel structure LiMn2O4 cathode material has the advantages of low cost and no toxicity because it does not contain any Cobalt.
However, the variability of the valency of Manganese and the Jahn-Teller effect of Mn3 + lead to issues with structural instability and poor reversibility of this component.
Different preparation methods have a greater impact on the electrochemical performance of LiMn2O4 cathode materials. Take the Act as an example: the Act of LiMn2O4 synthesized by the high-temperature solid-phase method is significantly higher than that of the Sol-Gel method. This phenomenon also has a lithium-ion diffusion coefficient mainly due to the different synthetic methods that have a greater impact on the crystallinity and morphology of the product.
LOW-TEMPERATURE CHARACTERISTICS OF PHOSPHATE ANODE MATERIALS
LiFePO4 has become the main body of the positive electrode material of batteries due to its excellent safety and stability in volume. However, the performance is not ideal due to its material as an insulator, low electronic conductivity, poor lithium-ion diffusivity, and poor conductivity at low temperatures. All these issues increase the internal resistance of the battery, which greatly affects the polarization and blocks the charge and discharge of the battery.
When studying the charge and discharge behavior of a LiFePO4 battery at low temperatures, it was found that its Coulomb efficiency decreased from 100% at 55 ° C to 96% at 0 ° C and 64% at –20 ° C. The discharge voltage decreased from 3.11V at 55 ° C to -20V at 2.62V.
In other studies, nano-carbon was used to modify a LiFePO4 battery, and it was discovered that the addition of the nano-carbon as a conductive agent reduced the sensitivity of LiFePO4’s electrochemical performance, as well as low-temperature performance. The discharge voltage of a modified LiFePO4 battery from 3.40V at 25 ° C dropped to 3.09V at –25 ° C, which is a decrease of only 9.12%. Its battery efficiency at –25 ° C came to 57.3%, which was higher than the 53.4% efficiency of a battery without nano-carbon as a conductive agent.
LiMnPO4 has also recently drawn great interest. A study found that LiMnPO4 has the advantages of high potential (4.1V), no pollution, low price, and large specific capacity (170mAh / g). However, because LiMnPO4 has a lower ionic conductivity than LiFePO4, Iron is often used in practice to partially replace Manganese to form a LiMn0.8Fe0.2PO4 solid solution.
4. Low-temperature characteristics of lithium-ion battery anode materials
For the following reasons, the low-temperature deterioration of the negative electrode material of a lithium-ion battery must be taken more seriously than that of one with the positive electrode material:
When charging and discharging at a low temperature and large rate, a battery undergoes severe polarization, a large deposit of lithium on the surface of the anode, and a lack of conductivity with the reaction product of lithium and the electrolyte.
From the perspective of thermodynamics, the electrolyte contains a large number of polar groups such as C–O, C–N, etc., which can react with the negative electrode material, and the SEI film formed is more susceptible to low temperatures.
Carbon anodes are difficult to insert lithium at low temperatures, and there is the asymmetry in the charge and discharge.
5. Research on Low-Temperature Electrolytes
The electrolyte has the role of transferring Lithium in the lithium-ion battery, and its ionic conductivity and SEI film-forming performance have a significant effect on the low-temperature performance of the battery.
There are three main indicators for judging the pros and cons of low-temperature electrolytes: the ionic conductivity, electrochemical window, and electrode reactivity.
The level of these three indicators depends largely on their constituent materials: solvents, electrolytes (lithium salts), and additives.
Compared to the chain carbonate, the low-temperature characteristics of the EC-based electrolyte have a tighter cyclic carbonate structure, a larger force, and a higher melting point and viscosity. However, the large polarity brought by the ring structure tends to have a large dielectric constant. EC solvents have a large dielectric constant, high ionic conductivity, and excellent film-forming properties, which effectively prevent the co-insertion of solvent molecules, making them indispensable. Therefore, most common low-temperature electrolyte systems are based on EC and the mixed Low melting point small molecule solvent.
Lithium salt is an important component of the electrolyte. Lithium salts in the electrolyte not only improve the ionic conductivity of the solution but also reduce the diffusion distance of Li + in the solution. In general, the greater the Li + concentration in the solution, the greater its ionic conductivity. However, the concentration of lithium ions in the electrolyte and the concentration of lithium salts are not linearly related but are parabolic. This is because the lithium-ion concentration in the solvent depends on the dissociation of the lithium salt in the solvent and the strength of the association.
6. Process factors
In addition to the battery composition itself, the process factors in the operation of a battery have a great impact on battery performance.
(1) PREPARATION PROCESS
Experts studied the effect of electrode load and coating thickness on the low-temperature performance of LiNi0.6Co0.2Mn0.2O2 / Graphite batteries and found that, in terms of capacity retention, the smaller the electrode load, the thinner the coating layer and the better its low-temperature performance.
(2) CHARGE AND DISCHARGE STATUS
Experts have studied the impact of low-temperature charge-discharge conditions on battery cycle-life and found that larger discharge depths will cause greater capacity loss and reduce cycle life.
(3) OTHER FACTORS
There are a multitude of other factors that affect the low-temperature performance of lithium-ion batteries: the surface area, pore diameter, electrode density, separator, and wettability of the electrode and electrolyte. The impact of material and process defects on the low-temperature performance of a battery cannot be ignored as well.
7. Assurance of low-temperature performance of lithium batteries
To ensure the low-temperature performance of lithium-ion batteries, the following points need to be achieved:
(1)SEI FILM
The formation of a thin and dense SEI film.
(2) THE ACTIVE MATERIAL
A large diffusion coefficient of the Li + in the active material.
(3) IONIC CONDUCTIVITY
High ionic conductivity of the electrolyte at low temperatures.
Research on low-temperature batteries has also begun into another type of lithium-ion battery: The all-solid-state battery. Compared to a conventional lithium-ion battery, all-solid-state batteries, especially those with thin-film, are expected to completely solve the issue of capacity degradation and the cycle safety of batteries used at low temperatures.
IATF16949
ISO13845
UL (UNDERWRITER LABORATORY)
CE (COMMUNATE EUROPIEA)
UN38.3
