Pumped storage, compressed air energy storage, and flywheel energy storage technologies all have the advantages of large capacity, long operating life, and high power density, but there are also some unavoidable problems.
Pumped storage is the most mature and lowest-cost energy storage technology with a series of technical advantages. However, the location of pumped storage power stations is restricted by geography, geology, water sources and other conditions, and its operation will cause water quality changes and ecological environment changes. Compressed air energy storage technology can be used in grid-level applications, but the technology has low energy conversion efficiency, is highly dependent on fossil fuels, and has very high requirements for geographic conditions. Flywheel energy storage technology has the advantages of high power density, long life, and insensitivity to ambient temperature. However, its self-discharge phenomenon makes flywheel energy storage systems too expensive for energy-based applications. Superconducting energy storage technology has a fast response speed and can provide short-term high-power. However, the current high-temperature superconducting wire technology is not mature, with high daily maintenance costs, large AC losses, and low safety and stability. It is still in the research and development stage, and the cost needs to be further reduced.
At present, due to differences in working principles, materials and manufacturing processes, compared with physical energy storage technology, chemical energy storage technology has relative advantages in terms of scale of use, convenience, R&D and development potential.
1. Fast charging and discharging speed
Chemical energy storage technologies such as lead storage batteries, lithium ion batteries, flow batteries, molten salt batteries, nickel-metal hydride batteries, and supercapacitors all have the technical advantage of fast charging and discharging. The 1.5C lithium-ion battery can be fully charged within 40 minutes, and its non-memory effect also enables the lithium-ion battery to be used as a storage device that can be charged and used. All vanadium redox flow batteries have good charge and discharge performance and can perform high-power repeated charging and discharging, while zinc bromide batteries have high-rate charge and discharge performance, and have good application prospects in electronic equipment, energy storage management and other fields.
2. High power density and energy density
Chemical energy storage batteries generally have the advantages of high power density and high energy density, and are suitable as power sources or energy storage devices. After research and development and improvement, advanced lead-acid batteries have both high energy density and high power density, and their power has been increased by 20% to 50%, overcoming the shortcomings of traditional lead-acid batteries, and becoming a new type of energy storage device in the current power supply field. The continuous improvement of lithium-ion batteries in terms of energy and power density will provide them with extensive application opportunities in the field of large-scale power grids in the future. Both zinc-bromide batteries and sodium-sulfur batteries have the characteristics of high energy density, have advantages in volumetric energy density, good power performance, and have great application potential in electronic equipment, transportation, and new energy access.
3. Fast response
Chemical energy storage batteries have certain advantages in response speed. For example, sodium-sulfur batteries, all-vanadium redox batteries, zinc-bromide batteries, etc. can release a large amount of energy in a short period of time, and they have certain opportunities in terms of grid peak shaving and temporary capacity expansion; lithium-ion batteries have a fast reaction speed and can provide MW-level instantaneous power output, and are suitable for power applications such as power frequency modulation.
4. Safe and stable operation
Lead-acid batteries exhibit safety, reliability, and stability during long-term use. Combined with their low cost, they are currently being widely used in the field of household energy storage. Lithium iron phosphate battery completely solves the safety hazards of lithium cobalt oxide and lithium manganate. The battery material deforms the least during the charging and discharging process, and the high temperature charging stability is good. When there is damage such as impact, heavy pressure, needle stick, short circuit, high voltage charging, high temperature, etc., there will be no explosion or combustion. This feature makes lithium iron phosphate battery the most distinctive lithium ion battery.
5. Friendly to the environment
The lithium ion production process and the raw materials used are clean and non-toxic, which is very environmentally friendly. The raw materials for flow batteries and sodium-sulfur batteries do not contain heavy metals, and the production process has little impact on the environment. Under normal circumstances, the sodium and sulfur elemental substances in waste sodium-sulfur batteries can be 100% recycled. People’s doubts about lead-acid batteries are mainly on the issue of lead pollution, but lead-acid battery pollution is not its technical nature. In normal operation, the electrolyte of the lead-acid battery will not leak from the battery terminal or the casing, and the special liquid-absorbing separator keeps the chemical raw materials inside. There is no free acid inside the battery, and the problem of lead pollution can be controlled by establishing a recycling system.
6. Flexible configuration and design
When the internal pressure of the lead-acid battery exceeds the normal level, the battery will release excess gas and automatically reseal to ensure that there is no excess gas in the battery. This feature makes lead-acid batteries simple to maintain, stable in quality, and can be placed in any position, making it easy to design and assemble the energy storage system. Flow batteries can be expanded by adding electrolyte tanks to facilitate capacity configuration for large-scale use. The flow battery system has independent power and capacity, and can be flexibly configured to facilitate the design of combination with other energy storage technologies, and facilitate the development of energy storage schemes according to actual needs.
7. Unrestricted installation environment and site selection
Chemical energy storage batteries have lower requirements for the installation environment and the selection of energy storage power stations. Since chemical energy storage has the advantages of environmental friendliness, easy design and assembly, it basically has no requirements for the installation environment. It will not have strict requirements on water sources, geology, and terrain like compressed air energy storage technology and pumped water storage technology. Therefore, chemical energy storage batteries can participate in the construction of power stations in the form of modules. For example, advanced lead-acid batteries can be widely used in household energy storage, community energy storage, and microgrid fields, without being restricted by location factors; the all-vanadium redox flow battery has a large degree of freedom in site selection and a small area. It can integrate solar and wind energy into residential or industrial sites.
