Waste batteries contain a large amount of heavy metals and electrolyte solutions such as waste acid and waste alkali. If discarded at will, heavy metals exuded from used batteries will cause pollution of water bodies such as rivers, rivers, lakes and seas, which indirectly threaten human health. Therefore, the recycling and disposal of waste batteries not only treats the source of pollution, but also realizes the recycling and reuse of resources.
At present, the power battery is mainly in the form of nickel-hydrogen battery and lithium battery. Hybrid battery currently uses nickel-hydrogen material, but since some technical performance of nickel-hydrogen battery is close to the theoretical limit value, it is not considered as the future development direction. . Relatively speaking, lithium-ion batteries are widely recognized for their high operating voltage, small size, no memory effect, low self-discharge, and long cycle life. Waste lithium-ion batteries usually contain 5% to 15% of cobalt, 2% to 7% of lithium, and 0.5% to 2% of nickel, and their recycling value is relatively high. Lithium-ion batteries also contain toxic substances such as lithium hexafluorophosphate, which will cause serious pollution to the environment and ecosystem. Heavy metals such as cobalt, manganese and copper will also endanger humans through the accumulation of bio-chains, which is extremely harmful. With the increasing application of lithium-ion batteries, it is of great social and economic significance to recover valuable metals in lithium-ion batteries, reduce environmental pollution, and alleviate resource shortages.
1 waste lithium ion battery valuable metal recycling technology
1.1 dry technology
In the dry method, lithium ion batteries are reduced and calcined to separate cobalt and aluminum, and the cobalt and acetylene black are separated by leaching.
Japan's Sony Corporation and Sumitomo Metal Mining Co., Ltd. have jointly studied the technology of recovering cobalt from waste lithium ion secondary batteries. The process is to incinerate the battery, filter the iron and copper, and then heat the residual powder and dissolve it in acid. Cobalt oxide can be proposed by extraction with an organic solvent .
ChurlKyoungLee et al.  first crushed the waste lithium-ion battery and then heat-treated to convert the combustible material into a gas, leaving LiCoO2. In a constant temperature water bath, nitric acid and hydrogen peroxide were added to dissolve LiCoO2, so that the leaching rates of Co and Li both reached 85%.
The dry process is relatively simple, but the energy consumption is high, and the combustion of the electrolyte solution and other components in the electrode is likely to cause air pollution.
1.2 wet technology
The wet method leaches the valuable components in the used battery with a mineral acid solution, and then recovers it by a certain method.
The lithium ion secondary battery positive electrode material was leached with hydrochloric acid at 80 ° C, and the leaching rates of Co and Li were all greater than 99%, and then Co was extracted with PC-288A (2-ethylhexylphosphoric acid-mono-2-ethylhexyl ether). After stripping, the cobalt is recovered in the form of cobalt sulfate. Further, a sodium carbonate solution was added to form a lithium carbonate precipitate, and the recovery rate was close to 80%.
KudoMistuhiko et al.  leached the lithium ion battery cathode waste with acid, added an amphoteric metal to the leachate, changed Co2+ to Co, and then removed the amphoteric metal to obtain the metal Co.
Wang Xiaofeng et al  first dissolve the electrode material in dilute hydrochloric acid, then adjust the pH = 4, selectively precipitate the aluminum hydroxide, and then adjust the pH to about 10, so that cobalt, nickel to form ammonia complex, re-pass O2 is oxidized by Co2+ and Ni2+, and the solution is passed through an ion exchange resin, and then Co and Ni are precipitated with oxalate.