Abstract:

In the process of Li-ion cell formation, a part of the active lithium from the cathode is consumed to form a solid-electrolyte interphase layer on the anode surface, resulting in an irreversible capacity loss. Especially in the case of adding high-capacity silicon-based anode materials to graphite, this kind of active lithium loss leads to an extremely low-first cycle coulomb efficiency and battery capacity. The problem can be effectively solved via the compensation of active lithium. The various ways used to supply active lithium are mainly divided into two categories: anode and cathode prelithiations. Anode prelithiation methods include physical mixing and chemical, self-discharge, and electrochemical pre-lithiations. The physical mixing lithiation method involves the addition of lithium metal powder to the anode or plate lithium metal foil to the anode surface, whereas the solution containing sacrificial lithium-rich compounds, such as butyl lithium, is used to prelithiate the anode in the case of chemical lithiation. Self-discharge lithiation is accomplished by the contact between the anode and lithium metal in the electrolyte. For electrochemical prelithiation, lithium metal is introduced into the battery as the third electrode, and the prelithiation is completed by discharging the anode. In the case of cathode prelithiation, sacrificial lithium-rich compounds with a high irreversible capacity are added to the cathode. Sacrificial lithium-rich compounds can be divided into binary lithium-containing compounds, such as Li₂O, Li₂O₂, and Li₂S; ternary lithium-containing compounds, including Li₆CoO₄ and Li₅FeO₄; organic lithium-containing compounds represented by Li₂DHBN and Li₂C₂O₄. The prelithiation technology can not only increase the capacity of lithium-ion cells but also benefit its cycling performances, especially for cells with silicon-containing anode. In this paper, the recent developments of lithium prelithiation technology are summarized, and several of our own works are introduced. The application prospect of lithium prelithiation technology is also forecasted.

Key words: lithium-ion batteries, anode prelithiation, cathode prelithiation