Battery energy storage technology mainly includes lead-acid batteries, lithium-ion batteries, flow batteries, sodium-based batteries, and other types of battery energy storage technologies.
Lead-acid battery energy storage
The lead-acid batteries used in energy storage projects include lead-acid batteries and lead-carbon batteries. The lead-carbon battery improves the negative electrode material based on the traditional lead-acid battery and combines the advantages of lead-acid batteries and supercapacitors. The carbon material added prevents negative electrode sulfation, significantly improving the battery’s cycle life. The cycle life of lead-carbon batteries has increased from 500-1000 times (60%-70% DOD, DOD is the discharge depth) of lead-acid batteries to 3700-4200 times (60%-70% DOD). In recent years, lead-carbon batteries with lower electricity cost have been the main application of lead-acid batteries in the energy storage field.
Lithium-ion battery energy storage
A wide variety of lithium-ion batteries are used in energy storage projects, including polymer lithium-ion batteries, lithium manganese oxide batteries, lithium titanate batteries, and rapidly developing lithium iron phosphate batteries, ternary lithium-ion batteries, and used lithium-ion batteries. From the perspective of one-time investment cost, cycle life, and safety, lithium iron phosphate is undoubtedly the lithium-ion battery energy storage system with the most comprehensive characteristics in the energy storage field and is widely used in various links of the power system. Lithium iron phosphate batteries have the advantages of high stability and long cycle life and are the most popular and widely used lithium-ion battery technology for power energy storage systems. In recent years, due to the cost reduction and performance improvement of lithium iron phosphate, this technology has been widely used in various links of the power system.
Sodium-based battery energy storage
Sodium-based batteries used in energy storage projects include high-temperature sodium-sulfur batteries, sodium-nickel batteries, and room-temperature water-based sodium-ion batteries. Sodium-sulfur batteries are the typical representative of sodium-based batteries and are the most mature energy storage technology (350-400 ℃) in high-temperature operation energy storage systems.
Used lithium-ion batteries for energy storage
The used lithium-ion batteries mainly refer to large quantities of power lithium-ion batteries for electric vehicles that have reached 80% of their initial capacity and have been retired, and have reuse value in some energy storage application fields through sorting, recombination, and integration.
Currently, the used lithium-ion batteries are still mainly lithium iron phosphate batteries. With the large-scale application of high-energy density ternary lithium-ion batteries, ternary lithium-ion batteries will gradually enter the used lithium-ion battery market in the future. Considering that the state parameters of retired lithium-ion batteries after 80% of the capacity have a large dispersion and great unpredictability, the integrated design of used lithium-ion batteries is difficult, and its application is mainly in small and decentralized application scenarios, such as communication base station backup power supply, peak shaving and filling in small photovoltaic configuration energy storage, etc.
Other types of battery energy storage
In addition to the above battery energy storage technologies, there are also supercapacitors, nickel-based batteries, and zinc-air batteries. Supercapacitors are power-type energy storage technologies, but their low energy density and short charging and discharging time limit their application in the energy storage field dominated by frequency modulation and capacity-type energy storage demand. Zinc-air batteries are currently the only air battery energy storage technology used in energy storage projects. Zinc-air batteries are mainly energy-type products with a rate greater than 2h. At present, the disadvantage of zinc-air batteries is that the system design is too complicated, the production automation level of products is low, and the system efficiency is still low (less than 75%).