Classification and prospects of lithium battery energy storage technology

　　So far, in response to different fields and different needs, people have proposed and developed a variety of energy storage technologies to meet applications. Global energy storage technologies mainly include physical energy storage, chemical energy storage (such as sodium-sulfur batteries, all-vanadium flow batteries, lead-acid batteries, lithium-ion batteries, supercapacitors, etc.), electromagnetic energy storage, and phase-change energy storage.

　　So far, people have proposed and developed a variety of energy storage technologies to meet the application in different fields and different needs. Global energy storage technologies mainly include physical energy storage, chemical energy storage (such as sodium-sulfur batteries, all-vanadium flow batteries, lead-acid batteries, lithium-ion batteries, supercapacitors, etc.), electromagnetic energy storage, and phase-change energy storage.　　1. Physical energy storage　　Physical energy storage technologies mainly include pumped water storage, compressed air energy storage, flywheel energy storage, and so on. Compared with chemical energy storage, physical energy storage is more environmentally friendly and greener, and is realized by using natural resources. Pumped Storage Hydroelectricity (PSH, Pumped Storage Hydroelectricity) is equipped with two upstream and downstream reservoirs. When the load is low, the equipment works in the state of the motor, and the water from the downstream reservoir is pumped to the upstream reservoir for storage, and the equipment works in the state of the generator during the peak load. , Using the water stored in the upstream reservoir to generate electricity, as shown in Figure 1. Due to mature technology, pumped storage power plants have become the most widely used energy storage technology in the power system. Currently, the installed capacity of pumped storage power stations under construction in China is about 11,400MW. It is estimated that the total installed capacity of pumped storage power stations will reach about 17,500MW by the end of 2010. Compressed Air Energy Storage (CAES, Compressed Air Energy Storage) is a gas turbine power plant for peak shaving. It mainly uses the surplus electricity from the grid load trough to compress air and store it in a high-pressure sealed facility with a typical gas storage pressure of 7.5 MPa. It is released during peak electricity consumption to drive gas turbines to generate electricity. The world's first commercial CAES power station was the Huntdorf power station built in Germany in 1978. It has an installed capacity of 290MW and an energy conversion efficiency of 77%. It has been started up more than 7,000 times since its operation, and is mainly used for hot standby and smooth load. Compared with pumped storage power stations, CAES power stations are flexible in site selection. They do not need to build ground reservoirs and the terrain conditions are easily met. At present, compressed air storage power stations have been widely used in some developed countries.　　Flywheel energy storage (FW, FlyWheels), realizes charging and discharging through the mutual conversion of mechanical energy and electrical energy. It uses a high-speed rotating flywheel core as a medium for mechanical energy storage, and uses a motor/generator and an energy conversion control system to control energy input and output. Flywheel energy storage requires high raw materials and technology for making flywheels. It was not until the 1990s that it was rapidly developed and used in uninterruptible power supply (UPS)/emergency power supply (EPS), grid peak shaving and frequency control. China's research in this area has just started.