CR1225 battery.What technologies are waiting for breakthroughs in power lithium battery packs?

　　What technologies are waiting for breakthroughs in power lithium battery packs? In the field of automotive power batteries, lithium batteries have become mainstream. At present, the energy density, high and low temperature characteristics, and rate performance of lithium battery packs are much higher than those of lead-acid and nickel-metal hydride batteries, but it is still difficult to meet the rapidly growing demand for electronic products, electric vehicles, etc. Now traditional lithium battery pack technology is approaching its bottleneck, and there is limited room for further optimization.

　　What technologies are waiting for breakthroughs in power lithium battery packs?

　　The key factors for the unsatisfactory development of China's energy vehicles include range, charging speed, and safety functions. These three factors are caused by the inadequate technology of power lithium battery packs. Therefore, they can also be regarded as the three technical bottlenecks of power lithium battery packs. .

　　1. Short cruising range: With the continuous advancement of technology, the cruising range of electric vehicles using lithium battery packs as power source has increased from less than 100 kilometers at the beginning to about 300 kilometers at that time, and the cruising range of a single model has exceeded 400 kilometers. However, there is still a certain distance compared with the 500 kilometers of the mainstream journey of fuel vehicles at that time. This problem can be solved by using multiple strings of single cells, but the negative problem is that it is too large and makes it inconvenient for the car to travel.

　　2. Slow charging speed: Compared with the short journey, the slow charging of lithium battery packs is a greater restriction on the development of electric vehicles. At normal speed, it takes 4 to 8 hours for the lithium battery of an electric vehicle to be fully charged. There are also quick-rechargeable lithium batteries that can be fully charged within 1 to 2 hours, but their negative effects are huge. The lifespan will be reduced to 1/3 of the original, and the battery performance will be significantly reduced. Fuel vehicles do not have these problems. The refueling time does not exceed 5 minutes, and safety and stability can be guaranteed.

　　3. Safety functions need to be improved: Since the birth of lithium battery packs, safety issues have always puzzled consumers. From mobile phones and laptops to now electric vehicles, safety accidents continue to occur. In addition to no reports of fires in electric vehicles from Nissan and Tesla, electric vehicles from China's Zotye and BYD, and the United States's General Motors and Fisker have all experienced spontaneous combustion or fires.

　　A battery system with a lithium battery pack specific energy significantly exceeding 0.25 kWh/kg has not yet been achieved. Therefore, for the mid-size car market, it is not theoretically possible for pure electric vehicles powered by lithium-ion battery packs to have a single charge range of more than 300 kilometers. Even if related products are available, the price will be unaffordable for ordinary consumers.

　　Development status of core technology of power lithium battery pack

　　Ternary lithium battery packs are about to reach a technical bottleneck, and solid-state batteries and fuel cells will move towards commercialization. Innovative layouts should be used to solve the technical shortcomings of electric vehicles and alleviate users' range anxiety. Until now, the service life of lithium batteries is still difficult to satisfy. Battery technology is still the biggest bottleneck in the evolution of all electronic devices. From an industrialization perspective, battery technology is still far from a revolutionary breakthrough. .

　　What is the core technology of power lithium battery?

　　Lithium batteries are representatives of modern high-performance batteries and are composed of four main parts: positive electrode material, negative electrode material, separator, and electrolyte.

　　The separator is an important component of the lithium battery pack and an important component that supports the electrochemical process of charging and discharging the lithium-ion battery. It is located between the positive and negative electrodes inside the battery, ensuring the passage of lithium ions while blocking electron transmission. The performance of the separator determines the interface structure, internal resistance, etc. of the battery, which directly affects the capacity, cycle, and safety performance of the battery. Excellent separators play an important role in improving the overall performance of the battery.

　　Electrolyte, lithium battery electrolyte is generally a mixture of high dielectric constant cyclic carbonate and low dielectric constant linear carbonate. Generally speaking, the electrolyte of lithium-ion battery should meet the requirements of high ionic conductivity (10-3~10-2S/cm), low electronic conductivity, wide electrochemical window (0~5V), and good thermal stability (-40~60℃ ) and other requirements. Lithium hexafluorophosphate and other new lithium salts, solvent purification, electrolyte preparation, and functional additive technology continue to advance. The current development direction is to further increase its operating voltage and improve the high and low temperature performance of the battery. Safe ionic liquid electrolytes and solid electrolytes are under development.

　　The negative electrode materials that can be used in power lithium battery packs include graphite, hard/soft carbon and alloy materials. Graphite is currently a widely used negative electrode material, and its reversible capacity can reach 360mA·h/g. Amorphous hard carbon or soft carbon can meet the needs of batteries for higher rate and lower temperature applications and is beginning to be used, but it is mainly mixed with graphite. Lithium titanate anode material has optimal rate performance and cycle performance and is suitable for high-current fast-charging batteries, but the battery produced has low specific energy and high cost.

　　Lithium iron phosphate battery packs have high safety and long life. Currently, nanoscale power materials and high-density lithium iron manganese phosphate materials are developing rapidly. The performance of high-energy and high-power materials tends to be stable, and the cost is further reduced. , gradually meeting the domestic market demand and the current needs of China's new energy vehicle promotion, high-voltage spinel lithium nickel manganate and high-voltage high specific capacity lithium-rich manganese-based cathode materials are still under development.

　　For a long time in the future, lithium battery packs will still be the most suitable electric vehicle batteries, including lithium manganate cathode materials, ternary system cathode materials, lithium iron phosphate cathode materials, composite carbon anode materials, ceramic coating separators, electrolyte salts The development of functional electrolyte technology supports the progress of battery technology and industrial development. As battery system technology advances in application, safety and reliability will be further improved in the coming years.

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