Breaking through battery safety technology, PI nickel plating, PET nickel plating is a key step

We have always firmly believed that high nickel and lithium iron phosphate are the two core directions for the future development of power battery technology, and one of the key issues in the long-term development of high nickel battery technology is battery safety. With the explosive demand and technological progress, we are optimistic that the high nickel penetration rate will accelerate and enter a long-term upward trend in 2022. We suggest focusing on the leading players in various aspects of new battery safety solutions.

abstract

The two demands of high performance and high safety have been present throughout the development of battery technology. According to China's "Energy saving and New Energy Vehicle Technology Roadmap 2.0" plan, by 2035, the specific energy of popular and high-end power batteries should reach 300Wh/kg and 500Wh/kg respectively. The existing battery technology has a significant gap compared to this target, and further exploration and matching of high-energy density electrode materials is one of the core primary goals of battery enterprises. However, in the existing battery system, high energy density electrodes have poor thermal stability and pose a risk to battery safety due to side reactions with the electrolyte, resulting in a situation where high energy density and high safety are difficult to balance. According to CIAPS statistics, the high nickel penetration rate in the domestic ternary cathode market has climbed month by month to 41% in October this year. Considering the prominent safety issues of high nickel batteries, we believe that solving safety problems is the key to the development of high nickel battery technology.

The upgrade of battery material system is committed to solving the inherent safety of batteries. Specifically, we believe that electrolyte modification can help improve the safety of high nickel, and materials such as LiFSI new lithium salts and flame retardant additives are expected to accelerate their application; 2. Solid state batteries are expected to receive attention, and semi-solid solutions have high compatibility with existing liquid battery processes, making them the first to achieve industrialization and significantly improving high nickel safety; 3. The penetration rate of coated membranes continues to increase, and the industrialization of new flame-retardant membranes is expected to accelerate; 4. New current collector materials such as PET coating can help improve high nickel safety and are expected to receive industry attention.

Multi dimensional construction of high nickel safety defense line for battery PACK. Specifically, we believe that: 1. The cylindrical 4680 packaging solution not only has the advantages of low heat dissipation and large heat dissipation area of traditional cylindrical battery cells, but also the full pole ear solution can further reduce internal resistance heating and increase pole ear heat dissipation channels, which is expected to be promoted; In terms of battery thermal management, liquid cooling technology, with its advantages of high heat transfer coefficient, fast rate, good temperature uniformity, and precise temperature control, supports the iteration of ternary technology towards high nickel; In terms of flame retardant materials, ceramicized silicone rubber has better characteristics than traditional flame retardant materials in terms of flame retardancy, mechanical properties, and preparation processes. We are optimistic about its accelerated penetration.

risk

The sales of new energy vehicles did not meet expectations, the installed capacity of high nickel ternary batteries did not meet expectations, and new battery technologies were iterated.

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PI nickel plated PET nickel plated power batteries are developing towards high nickel, and safety indicators are being prioritized

The primary goals of battery technology development are high performance and high safety. According to China's "Energy saving and New Energy Vehicle Technology Roadmap 2.0" plan, by 2035, the specific energy of popular and high-end power batteries should reach 300Wh/kg and 500Wh/kg respectively. The existing battery technology has a significant gap compared to this target, and further exploration and matching of high-energy density electrode materials is an important path. However, in the existing liquid lithium battery system, high energy density electrodes have poor thermal stability and pose a risk to battery safety due to side reactions with the electrolyte, resulting in a situation where high energy density and high safety are difficult to balance. Specifically:

From the perspective of battery structure, the high-temperature rupture of the separator and the combustion of liquid electrolyte directly caused thermal runaway of the battery cell. Based on the abuse model of battery thermal runaway, the process of battery thermal runaway can be divided into the following stages: battery overheating - SEI layer decomposition - separator melting - positive electrode decomposition reaction - binder decomposition and electrolyte combustion. The rupture of the diaphragm and the combustion of the electrolyte correspond to the initial and peak stages of thermal runaway in the battery, respectively. Therefore, the structure of traditional diaphragm liquid electrolyte directly affects the thermal stability of the battery.

From the perspective of electrode materials, high-energy density electrode materials have poor intrinsic thermal stability and are prone to side reactions with electrolytes, which can damage the material structure and affect battery safety. In order to pursue the improvement of energy density, from the perspective of positive electrode materials, the current high certainty technology route is to explore the potential of high nickel ternary materials. However, the intrinsic thermal stability of ternary materials continues to decrease with increasing Ni content, manifested as a decrease in thermal stability temperature and an increase in calorific value during thermal runaway, increasing the possibility of thermal runaway occurring. In addition, high-energy density cathodes (such as high nickel ternary, high-voltage LCO, lithium rich manganese based materials, etc.) and lithium metal anodes will undergo side reactions with liquid electrolytes during charging and discharging, manifested as phenomena such as transition metal dissolution, oxygen evolution of positive electrode materials, and continuous generation of SEI. Side reactions affect the stability of electrode materials, damage battery structure, and directly endanger battery safety.

From the perspective of electrolyte, additives in the electrolyte are prone to mutual interference, making modification difficult. The additives in the electrolyte directly affect key issues such as the electrochemical window of the electrolyte and the stability of the electrode/electrolyte interface. Due to the fact that additives usually exist in the form of solutes in organic electrolyte solvents, the mutual reactions and interferences between additives and additive solvents can make it difficult for additives to achieve ideal effects in complex electrolyte systems.