Development status of power battery technology

As the energy storage device of new energy vehicles, the performance of power battery directly affects the market application of new energy vehicles and the acceptance of ordinary consumers, such as safety, specific energy, energy density, specific power, life and cost. At present, lead-acid batteries, nickel-hydrogen batteries and lithium-ion batteries are all used in the field of electric vehicles. Lithium-ion battery is the electrochemical system with the highest energy density among the industrialized power battery products. It has a long cycle life and service life, and its safety is continuously improved.

At the same time, lithium-ion batteries are already in the stage of automated mass production, and the cost is falling. As a technology and industrial upgrading product of lead-acid battery and nickel-metal hydride battery, lithium-ion battery has outstanding advantages such as high specific energy, high specific power, low self-discharge rate, no memory effect and environmental friendliness, and has become the current technology research and industrialization. Its application areas cover hybrid electric vehicles, plug-in hybrid electric vehicles, pure electric vehicles and hydrogen fuel cell vehicles.

At present, lithium-ion battery products are mainly used in pure electric vehicles and plug-in hybrid electric vehicles, but the driving range of pure electric vehicles is shorter than that of conventional fuel vehicles (the driving range of pure electric drives is mostly about 200km), and the cost of power batteries is still Higher [the price of the battery system is roughly 2~2.5 USD/(W·h)], and the safety performance needs to be further improved and improved. Therefore, the world’s major automobile producing countries are continuing to support the development of power battery technology innovation research and expansion of industrial scale, especially to further improve the safety and specific energy of power batteries (from the current specific energy of battery cells to 110~250W·h/kg) to 300~350W·h/kg), specific power and service life, and further reduce manufacturing and use costs.

At present, the R&D and industrialization of power batteries around the world are mainly concentrated in three regions, which are located in Germany, the United States and East Asia where China, Japan and South Korea are located. For a long time, China, Japan and South Korea have dominated the technology and market in the field of small lithium-ion batteries for consumer electronics, and the production of lithium-ion power batteries is currently mainly concentrated in these three countries. From the perspective of technology and industry, Japan is still leading in technology, South Korea surpasses Japan in market share and occupies the first place, while China has the largest number of battery companies and the largest production capacity.

Judging from the lithium-ion power battery products mass-produced by power battery companies at home and abroad, the existing lithium-ion power battery products can be basically divided into two categories: one is small-capacity cylindrical batteries (18650 batteries are typical representative products, For other types such as 20700, 21700 and 26650, etc.), the battery system needs to use multiple series and parallel connections to meet the requirements of total voltage and total capacity.

The number of batteries reaches thousands, and the connection between batteries and the management of heat and electricity are complicated; the other type uses large-capacity batteries, which are usually packaged with aluminum-plastic film or welded with metal shells. Due to the large capacity of the battery, the number of single cells required by the battery module and system is greatly reduced, and the connection between the batteries and the management of heat and electricity are relatively simple.

After more than 20 years of continuous support and development, the key materials of my country’s power batteries have basically been localized. The technical research and product development of key materials and power battery companies have transitioned from the catch-up period to the synchronous development period. The total production capacity of power batteries ranks first in the world, which strongly supports the demonstration, promotion and application of new energy vehicles in my country.

Through the strong support of the three five-year plans (2001-2015), the material system selection of power batteries in my country has become diversified. On the premise of improving and enhancing safety, we seek to greatly increase the energy density of power batteries. is an inevitable trend.

At present, my country has formed a relatively complete lithium-ion power battery industry including key materials (positive electrode, negative electrode, diaphragm and electrolyte, etc.), power battery, system integration, demonstration application, recycling, production equipment, basic research and development, etc. The chain system has mastered the formula design, structural design and manufacturing process technology of power batteries, and the production line has gradually transitioned from semi-automatic pilot test to fully automatic large-scale manufacturing. Four major power battery industrialization clusters have been formed, including the Pearl River Delta, the Yangtze River Delta, the Central Plains region and the Beijing-Tianjin region.

According to statistics, more than 100 power battery companies have carried out the research and development and industrialization of power batteries and battery systems, and the investment of more than 100 billion USD of industrial capital has formed an annual production capacity of more than 40 billion watt hours, and the progress of technology research and development and industrialization Significantly.