What is the development direction and prospect of energy storage technology?

　　The development of energy storage technology is the key to ensuring the large-scale development of clean energy and the safe and economic operation of the power grid. Energy storage technology can add electric energy storage links in the power system, making the "rigid" power system with real-time power balance more "flexible", especially to smooth the volatility caused by large-scale clean energy power generation access to the grid, and improve the operation of the grid The safety, economy, and flexibility. Energy storage technology is generally divided into thermal energy storage and electric energy storage. The future application of the global energy Internet is mainly electric energy storage.

　　The development of energy storage technology is the key to ensuring the large-scale development of clean energy and the safe and economic operation of the power grid. Energy storage technology can add electric energy storage links in the power system, making the "rigid" power system with real-time power balance more "flexible", especially to smooth the volatility caused by large-scale clean energy power generation access to the grid, and improve the operation of the grid The safety, economy, and flexibility. Energy storage technology is generally divided into thermal energy storage and electric energy storage. The future application of the global energy Internet is mainly electric energy storage.　　Electric energy storage technology is mainly divided into three categories: physical energy storage, electrochemical energy storage and electromagnetic energy storage.　　Physical energy storage　　Pumped water storage is currently the most mature energy storage technology, with low energy storage costs, and large-scale applications have been realized. At present, the total installed capacity of pumped storage units in the world exceeds 100 million kilowatts, and Japan, the United States, and China rank among the top three in terms of installed capacity. The world is rich in hydropower resources. Through rational use of terrain, larger capacity pumped storage units can be built to better ensure the safety of power supply to the power grid. Compressed air energy storage is the use of surplus electricity in the trough of the power system to drive the air compressor to press air into the large-capacity air storage chamber, which is to convert electrical energy into storable compressed air potential energy. When the system's power generation capacity is insufficient, the compressed air will be compressed Combustion with oil or natural gas to drive the gas turbine to generate power and meet the needs of system peak shaving. Compressed air energy storage has the advantages of large capacity, long service life, and good economy. However, it needs to consume fossil energy when generating electricity, resulting in pollution and carbon emissions.　　Electrochemical energy storage　　Electrochemical energy storage is currently the most cutting-edge energy storage technology. In recent years, electrochemical energy storage technologies such as sodium-sulfur batteries, flow batteries and lithium-ion battery energy storage have developed rapidly, with huge development potential and broad application prospects, and are expected to be the first to enter the commercial development stage. In the future, it is necessary to achieve technological breakthroughs in battery materials, manufacturing processes, system integration, and operation and maintenance to reduce manufacturing and operating costs.　　 Lead-acid battery has a history of more than 140 years. It is the most mature battery energy storage technology with mature technology, low price and high safety. It currently accounts for more than half of the battery market and is mainly used for electric bicycles. However, lead-acid batteries have low energy density, high mass, and toxic materials, and are not suitable for grid energy storage.　　 Sodium-sulfur battery has high energy density, which is convenient for modular manufacturing, transportation and installation, and is suitable for emergency power supply for special loads.　　The flow battery has large capacity, the electrolyte can be recovered, and the cycle life is long. The capacity and power can be designed separately.　　 Lithium-ion battery is a battery in which a compound containing lithium ions is used as the positive electrode and a carbon material is used as the negative electrode. Lithium-ion batteries have superior cycle performance, long service life, and do not contain toxic and harmful substances, so they are called green batteries. At present, lithium-ion batteries are widely used in mobile phones, notebook computers, electric vehicles and other fields, but the cost of a single charge and discharge cycle exceeds 1 yuan/kWh, and it is not economical to be applied to power systems and large-scale energy storage. Metal-air battery is a new type of fuel cell formed by replacing hydrogen energy in traditional fuel cell with metal fuel. It is non-toxic, non-polluting, stable discharge voltage, high energy density, low internal resistance, long service life, and relatively low price. Many advantages such as low, low process technology requirements. Metal-air batteries have cheap and abundant raw materials and can be recycled and are expected to become a new generation of green energy storage batteries. Electromagnetic energy storage supercapacitors are electrochemical components developed in the 1970s and 1980s that store energy through polarized electrolytes. There is no chemical reaction in the energy storage process. Because the energy storage process is reversible, the supercapacitors can be repeatedly charged and discharged hundreds of thousands. Second-rate. Supercapacitors have high power density, short charge and discharge time, long cycle life, and wide operating temperature range, but they have low energy storage capacity and are not suitable for large-scale energy storage in power grids. Superconducting magnetic energy storage is an energy storage device made with the characteristics of zero resistance of superconductors. It has the advantages of large instantaneous power, light weight, small size, no loss, and fast response. It can be used to improve the stability of the power system and improve the quality of power supply. . However, superconducting magnetic energy storage has low energy density, limited capacity, and is subject to superconducting material technology, so the future prospects are still unclear.　　Development direction and prospect　　Large-scale energy storage can be used for peak shaving and valley filling of the global energy Internet. Large-scale, long-term energy storage facilities such as pumped water storage and compressed air energy storage can be used for peak shaving of large power grids. The flow battery has large energy storage, many cycles, and long life. It can be used as a supplement to the peak shaving energy storage device of the power grid. Hydrogen energy storage can be used to store surplus wind and solar energy to provide power for fuel cell vehicles.　　 Large-scale power-type energy storage can be used to stabilize the volatility of large-scale clean energy. Power-type energy storage equipment such as supercapacitors, superconducting magnetic energy storage, flywheel energy storage, sodium-sulfur batteries, etc. are mainly operated in conjunction with large-scale renewable energy, which can quickly respond to the output of wind power and photovoltaic power generation, and stabilize the fluctuation of renewable energy , To ensure the safety of real-time operation of the power grid.　　Small energy storage batteries can be used in electric vehicles. Lithium batteries, new lead-acid batteries, metal-air batteries and other energy storage devices have high energy and power density, but the battery identity is poor, and it is difficult to form large-capacity battery packs. They are not suitable for large-scale power stations and are mainly used for electric vehicles. With the extension of battery life and the reduction of cost, energy storage batteries can meet the needs of large-scale development of electric vehicles. In the future, electric vehicle energy storage batteries will be connected to the global energy Internet, and through reasonable arrangements of charging time, assist grid peak shaving to achieve low-valley charging and peak discharge.　　The key to the progress of energy storage technology lies in the breakthrough of material technology. With the continuous innovation and development of new energy storage materials, important breakthroughs are expected to be made in terms of extending the service life of energy storage components, increasing energy density, shortening charging time, and reducing costs.