button cell battery cr2025

New materials or technologies are needed to achieve a breakthrough in button cell battery cr2025

The development of button cell battery cr2025 is at a bottleneck period, and the energy density is close to its physical limit. We need new materials or technologies to achieve a breakthrough in button cell battery cr2025. The following battery materials have been favored by industry insiders and may become a breakthrough in breaking the barriers of button cell battery cr2025.

1. Silicon-carbon composite negative electrode material

With the large screen and diversified functions of digital terminal products, new requirements are put forward for battery life. The current gram capacity of lithium battery materials is low and cannot meet the growing demand of terminals for batteries.

As a kind of future negative electrode material, the theoretical gram capacity of silicon-carbon composite materials is about 4200mAh/g or more, which is more than 10 times higher than the 372mAh/g of graphite negative electrodes. After its industrialization, it will greatly increase the capacity of the battery.

The main problems of silicon-carbon composite materials are:

During the charging and discharging process, the volume expansion can reach 300%, which will cause the silicon material particles to pulverize and cause the material capacity loss. At the same time, the liquid absorption capacity is poor.

The cycle life is poor. At present, the above problems are being solved through silicon powder nano-crystallization, silicon-carbon coating, doping and other means, and some companies have made certain progress.

Related R&D companies:

At present, major material manufacturers are developing silicon-carbon composite materials, such as BTR, Snow, Xingcheng Graphite, Huzhou Chuangya, Shanghai Shanshan, Huawei, Samsung, etc. The situation of domestic negative electrode material companies developing silicon-based materials is that most material manufacturers are still in the R&D stage, and only Shanghai Shanshan has entered the pilot mass production stage.

2. Lithium titanate

In recent years, the domestic enthusiasm for the research and development of lithium titanate is relatively high.

The main advantages of lithium titanate are:

Long cycle life (up to 10,000 times or more), belonging to zero strain material (volume change is less than 1%), no traditional SEI film is generated;

High safety, high lithium insertion potential, no dendrites, and extremely high thermal stability during charging and discharging;

Can be charged quickly.

The main factor restricting the use of lithium titanate at present is that the price is too high, higher than traditional graphite, and the gram capacity of lithium titanate is very low, about 170mAh/g. Only by improving the production process and reducing the production cost, the advantages of lithium titanate such as long cycle life and fast charging can be brought into play. Combined with the market and technology, lithium titanate is more suitable for buses and energy storage fields that do not require space.

Related R&D companies:

Zhuhai Yinlong, Sichuan Xingneng, Huzhou Weihong Power Co., Ltd., Shenzhen Beite New Energy Materials Co., Ltd., Hunan Shanshan New Materials Co., Ltd., and several smaller lithium titanate manufacturers in Anhui and Shenzhen.

3. Graphene

Since winning the Nobel Prize in 2010, graphene has attracted global attention, especially in China. A wave of graphene research and development has been set off in China. It has many excellent properties, such as good light transmittance, excellent electrical conductivity, high thermal conductivity, and high mechanical strength.

The potential applications of graphene in lithium-ion batteries are:

As a negative electrode material. Graphene has a high gram capacity, with a reversible capacity of about 700mAh/g, which is higher than the capacity of graphite negative electrodes. In addition, graphene's good thermal conductivity ensures its stability in the battery system, and the interlayer spacing of graphene is larger than that of graphite, which allows lithium ions to diffuse smoothly between graphene sheets, which is beneficial to improving battery power performance. Due to the immature production process of graphene and the unstable structure, there are still some problems with graphene as a negative electrode material, such as low first discharge efficiency of about 65%; poor cycle performance; high price, which is significantly higher than traditional graphite negative electrode.

As a positive and negative electrode additive, it can improve the stability of button cell battery cr2025, extend the cycle life, and increase internal conductivity.

Given the immature mass production process, high price and unstable performance of graphene, graphene will be used first as a positive and negative electrode additive in lithium-ion batteries.

Related R&D companies:

Jiawei Co., Ltd., Dongxu Optoelectronics, Qingdao Haoxin New Energy, Xiamen Kaina, etc.

4. Carbon nanotubes

Carbon nanotubes are a type of carbon material with a graphitized structure. They have excellent electrical conductivity. At the same time, due to their small depth and short travel when deintercalating lithium, they have a small polarization effect when used as negative electrode materials at high rates of charge and discharge, which can improve the high-rate charge and discharge performance of the battery.

Disadvantages:

When carbon nanotubes are directly used as negative electrode materials for button cell battery cr2025, there will be problems such as high irreversible capacity, voltage hysteresis, and unclear discharge platform. For example, Ng et al. prepared single-walled carbon nanotubes by simple filtration and used them directly as negative electrode materials. Their first discharge capacity was 1700mAh/g and their reversible capacity was only 400mAh/g.

Another application of carbon nanotubes in negative electrodes is to combine with other negative electrode materials (graphite, lithium titanate, tin-based, silicon-based, etc.), using their unique hollow structure, high conductivity and large specific surface area as carriers to improve the electrical properties of other negative electrode materials.

Related R&D companies:

Tiannai Technology, Nanoport, etc.

5. Lithium-rich manganese-based positive electrode materials

High capacity is one of the development directions of button cell battery cr2025, but the energy density of lithium iron phosphate in the current positive electrode materials is 580Wh/kg, and the energy density of lithium nickel cobalt manganese oxide is 750Wh/kg, both of which are relatively low. The theoretical energy density of lithium-rich manganese-based materials can reach 900Wh/kg, becoming a research and development hotspot.

The advantages of lithium-rich manganese-based materials as positive electrode materials are:

High energy density and abundant main raw materials.

Due to the short development time, lithium-rich manganese-based materials currently have a series of problems:

The first discharge efficiency is very low, the material releases oxygen during the cycle process, which brings safety hazards, the cycle life is very poor, and the rate performance is low.

The current means to solve these problems include coating, acid treatment, doping, pre-cycling, heat treatment, etc. Although lithium-rich manganese-based materials have obvious advantages in gram capacity and huge potential, they are limited by slow technological progress and it will take time for them to be put on the market in large quantities.

Related R&D companies:

Ningbo Institute of Materials, Chinese Academy of Sciences, etc.

6. Power-type nickel cobalt manganese oxide materials

There has always been a lot of controversy about the route of power batteries, so lithium iron phosphate, lithium manganese oxide, ternary materials and other routes have been adopted. The domestic power battery route is mainly lithium iron phosphate, but with the popularity of Tesla around the world, the ternary material route it uses has caused a wave of enthusiasm.

Although lithium iron phosphate is highly safe, its low energy density is an insurmountable weakness, and new energy vehicles require longer driving range. Therefore, in the long run, materials with higher gram capacity will replace lithium iron phosphate and become the next generation of mainstream technology route.

Nickel cobalt manganese oxide ternary materials are most likely to become the mainstream material for the next generation of domestic power batteries. China has successively launched electric vehicles with ternary routes, such as BAIC E150EV, JAC IEV4, Chery EQ, Wei Lan, etc., and the unit weight density is greatly improved compared with lithium iron phosphate batteries.

Related R&D companies:

Hunan Shanshan, Dangsheng Technology, Xiamen Tungsten Industry, Keheng Shares, etc.

7. Coated diaphragm

The diaphragm is crucial to the safety of button cell battery cr2025, which requires the diaphragm to have good electrochemical and thermal stability, and to maintain high wettability to the electrolyte during repeated charging and discharging.

Coated diaphragm refers to coating adhesives such as PVDF or ceramic alumina on the base film. The functions of coated diaphragm are:

1. Improve the heat shrinkage resistance of the diaphragm to prevent large-area short circuit caused by diaphragm shrinkage;

2. The thermal conductivity of the coating material is low, which prevents certain thermal runaway points in the battery from expanding to form overall thermal runaway.

Related R&D companies:

Xingyuan Materials, Shanghai Enjie, Sinoma Technology, Yiteng Diaphragm, Tianjin Donggao, Putailai, etc.

8. Ceramic Alumina

Among coated diaphragms, ceramic coated diaphragms are mainly aimed at power battery systems, so their market growth space is larger than that of coated diaphragms, and the market demand for its core material ceramic alumina will increase significantly with the rise of ternary power batteries.

The purity, particle size and morphology of ceramic alumina used to coat the diaphragm have very high requirements. The products of Japan and South Korea are more mature, but the price is more than twice as expensive as domestic products. There are also many domestic companies currently developing ceramic alumina, hoping to reduce dependence on imports.

Related R&D companies:

Guocera Materials, etc.

9. High-voltage electrolyte

Increasing battery energy density is one of the trends of button cell battery cr2025. There are currently two main methods to increase energy density:

One is to increase the charging cut-off voltage of traditional positive electrode materials, such as increasing the charging voltage of lithium cobalt oxide to 4.35V and 4.4V. However, the method of increasing the charging cut-off voltage is limited. Further increasing the voltage will cause the structure of lithium cobalt oxide to collapse and its properties to be unstable;

The other is to develop new positive electrode materials with higher charging and discharging platforms, such as lithium-rich manganese-based, nickel cobalt oxide, etc.

After the voltage of the positive electrode material is increased, a high-voltage electrolyte is required to match it. Additives play a key role in the high-voltage performance of the electrolyte, which has become a research and development focus in recent years.

Related R&D companies:

Xinzhoubang, Tianci Materials, etc.

10. Water-based binder

Currently, the main cathode material uses PVDF as a binder, which is dissolved in an organic solvent. The binder system of the negative electrode includes SBR, CMC, fluorinated olefin polymers, etc., and organic solvents are also used. In the process of electrode sheet production, the organic solvent needs to be dried and volatilized, which not only pollutes the environment but also harms the health of employees. The dried and evaporated solvent needs to be collected and processed with special refrigeration equipment, and the fluorinated polymer and its solvent are expensive, which increases the production cost of button cell battery cr2025.

In addition, SBR/CMC binders are easy to stick to the roller during processing and are difficult to use in the preparation of cathode sheets, so the scope of use is limited.

For the sake of environmental protection, cost reduction, and increased performance of the electrode sheet, the development of water-based binders is imperative.

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