Classification of lithium battery energy storage technology -Lithium - Ion Battery Equipment
1. Physical energy storage
Physical energy storage technologies mainly include pumped storage, compressed air energy storage, flywheel energy storage, etc. Compared with chemical energy storage, physical energy storage is more environmentally friendly and green, using natural resources to achieve. Pumped storage power station (PSH, PumpedStorageHydroelectricity) is equipped with two reservoirs upstream and downstream. When the load is low, the equipment works in the state of electric 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 when the load peaks. , using the water stored in the upstream reservoir to generate electricity, see Figure 1. Due to the mature technology, pumped storage power stations 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 my country is about 11,400MW.(Lithium - Ion Battery Equipment)
Compressed Air Energy Storage Power Station (CAES, Compressed Air Energy Storage) is a gas turbine power plant for peak shaving. It mainly uses the surplus power when the grid load is low to compress air, and stores it in a high-pressure sealed facility with a typical gas storage pressure of 7.5MPa. It is released during peak electricity consumption to drive the gas turbine to generate electricity. The world's first commercialized CAES power station was the Huntdorf power station built in Germany in 1978, with an installed capacity of 290MW and an energy conversion efficiency of 77%. Since its operation, it has accumulated more than 7,000 starts, mainly for hot backup and load smoothing. Compared with the pumped storage power station, the CAES power station is flexible in site selection. It does not need to build a ground reservoir, and the terrain conditions are easy to meet. At present, the compressed air storage power station has been widely used in some developed countries.
Flywheel energy storage (FW, FlyWheels) is to achieve charging and discharging through the mutual conversion of mechanical energy and electrical energy. It uses a high-speed rotating flywheel iron core as a medium for mechanical energy storage, and uses a motor/generator and an energy conversion control system to control the input and output of energy. Flywheel energy storage has high requirements on the raw materials and technologies for making flywheels. It was not developed rapidly until the 1990s, and it was used in the fields of uninterruptible power supply (UPS)/emergency power supply (EPS), power grid peak regulation and frequency control. my country's research in this area has just started.
Physical energy storage such as pumped hydro energy storage and compressed air energy storage have the advantages of large scale, long cycle life and low operating costs, but they require special geographical conditions and sites, have large limitations in construction, and have high one-time investment costs. Not suitable for smaller power off-grid power generation systems. From the perspective of development level and practicality, chemical energy storage has broader application prospects than physical energy storage.
2. Chemical energy storage—lithium-ion battery energy storage is the most feasible technical route at present
Lead-acid batteries are the oldest and most mature chemical energy storage method, with a history of more than 100 years, and are widely used in automotive starting power, electric bicycle or motorcycle power, backup power and lighting power. Lead-acid battery electrodes are mainly made of lead and its oxides, and the electrolyte is a sulfuric acid solution. When charging, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; when discharging, the main component of the positive and negative electrodes is lead sulfate. Lead-acid batteries have good reliability, readily available raw materials, and low prices, but their optimal charging current is about 0.1C, the charging current cannot be greater than 0.3C, and the discharge current is generally required to be between 0.05 and 3C, which is difficult to meet the power and capacity at the same time. Take into account the large-scale power storage requirements.