With the increase in the number of electric vehicles in China, the number of retired lithium-ion electric car batteries has also increased significantly. According to EVtank statistics, the cumulative decommissioning of automotive power batteries exceeded 200,000 tons(about 25 GWh) in 2020 and is expected to reach 960,000 tons(116 GWh) by 2025 in China. And recycling retired power batteries has become a complicated problem to solve. Failure to recycle retired lithium-ion batteries can seriously impact the natural environment. If by technically extracting the recovered lithium-ion batteries, many materials can be reused.
The recycling of power batteries is divided into two-cycle processes: echelon use and dismantling recycling, starting from echelon use.
What Is Echelon Use?
Echelon use—refers to conducting a necessary inspection, classification, disassembly, and battery repair of used lithium-ion electric car batteries (including the New Old Stock and defective items) and consistency screening so they can be reused in other fields.
Echelon use can ease the pressure of recycling, reduce environmental pollution, improve economic efficiency, and help the development of renewable energy.
Dismantling recycling belongs to severe scrapping. Generally, the battery capacity has been seriously depleted and cannot be used any longer. The purpose of recycling can only be achieved by chemically extracting precious metals such as nickel, cobalt, and lithium in batteries.
How to Screening used LiFePO4 Batteries
The purpose of screening is to select cells with similar parameters.
Static sorting is to screen the open circuit voltage, internal resistance, capacity, and other characteristic parameters of the battery cells, select the target parameters, introduce statistical algorithms, set the screening criteria, and divide the same batch of cells into several groups.
Dynamic sorting is to screen the characteristics of the battery cells during the charging and discharging process. Some choose the constant current and voltage charging process, some choose the pulse impact charging and discharging process, and some compare their own charging and discharging curves relation.
Combining dynamic and static sorting, static screening is used for preliminary grouping and dynamic screening is performed on this basis. This way, more groups are divided, and the screening accuracy is higher, but the cost will increase accordingly.
Lithium iron Phosphate(LiFePO4-LFP) Battery: The Main Force of Echelon Use
LiFePO4, NCA, and NMC batteries are currently the most used in electric vehicles.
Echelon-use batteries are mostly LFP batteries, and the capacity of LiFePO4 batteries tends to decay slowly with the increase in cycle times. When the battery capacity decays to 80%, the lithium iron phosphate batteries retired from the car still have more cycles and have a high utilization value.
The cycle life of LiFePO4 batteries is more than 3,500 times, and some can reach 5,000 times. At the same time, the capacity decays slowly with the number of cycles. In addition, LFP cells do not contain metals such as cobalt, lithium, and nickel, and the resource recovery value is low.
Therefore, used LiFePO4 batteries are generally echelon used as energy storage batteries. Used NCA and NMC batteries are more suitable for resource recovery because they can extract metals like nickel, cobalt, and lithium.
The Application of Used LiFePO4 Battery
Most of the used LFP batteries that have passed the consistency screening are divided into grades” A ” and” B ” for sale again in the market. This is an open fact in China. They can be used as a wind, solar, and electricity battery energy storage system(BESS), a backup power source for communication base stations, or in low-speed electric vehicles, electric motorcycles, and other scenarios requiring relatively low battery performance.
Performance of Second-Hand LiFePO4 Batteries
After second-hand LiFePO4 batteries are used in series and parallel groups for some time, many abnormal changes and phenomena will occur, which are manifested in the following aspects:
- Voltage changes, the voltage of the battery always has the problem of excessively high and low voltage of individual unit cells during charging and discharging;
- Significant shortening of charge and discharge duration;
- The charge and discharge capacity becomes less, far lower than the initial stage of use;
- With load capacity changes, the same load, especially inductive loads, such as motors, has a rapid decline in power performance;
- The battery temperature heats up too fast.
Disadvantages of Used Valence LiFePO4 Batteries
Battery capacity loss: The battery capacity conforms to the “barrel principle,” and the capacity of the worst cell determines the capacity of the entire battery pack.
Battery life loss: Small-capacity batteries are fully charged and discharged every time and are likely to reach the limit of use first.
Battery’s internal resistance increases: the battery generates relatively more heat. Internal resistance and temperature rise form a pair of negative feedback, accelerating the deterioration of high internal resistance cells.
How to Avoid Buying Used LiFePO4 Battery
Don’t buy cells missing a logo, branding, serial numbers, and model numbers or with a fake QR code.
The only way to Buy directly from a real brand manufacturer. Such as Thunder Sky Winston. As currently the largest exporter of LFP Cell manufacturers in China, After more than 20 years of development, Winston Battery is well proven in the market and has been selling well in more than 36 countries and regions in Europe, Asia, North America, and Africa.
Conclusion
Batteries are as important as human organs, and discarding them will cause severe environmental pollution and health risks. If retired batteries are not treated properly, harmful substances such as electrolytes and heavy metals will cause major harm to groundwater, air, soil, energy waste, and human health. As an emerging industry, the lithium-ion industry continues to grow, and the demand for environmental protection and sustainable development has also prompted people to pay more and more attention to this industry.