A review: pre‐lithiation strategies based on cathode sacrificial lithium salts for lithium‐ion capacitors

Similar to lithium‐ion batteries (LIBs), during the first charge/discharge process of lithium‐ion capacitors (LICs), lithium‐intercalated anodes (e.g., silicon, graphite, and hard carbon) also exhibit irreversible lithium intercalation behaviors, such as the formation of a solid electrolyte interface (SEI), which will consume Li + in the electrolyte and significantly reduce the electrochemical performance of the system. Therefore, pre‐lithiation is an indispensable procedure for LICs. At present, commercial LICs mostly use lithium metal as the lithium source to compensate for the irreversible capacity loss, which has the demerits of operational complexity and danger. However, the pre‐lithiation strategy based on cathode sacrificial lithium salts (CSLSs) has been proposed, which has the advantages of low cost, simple operation, environmental protection, and safety. Therefore, there is an urgent need for a timely and comprehensive summary of the application of CSLSs to LICs. In this review, the important roles of pre‐lithiation in LICs are detailed, and different pre‐lithiation methods are reviewed and compared systematically and comprehensively. After that, we systematically discuss the pre‐lithiation strategies based on CSLSs and mainly introduce the lithium extraction mechanism of CSLSs and the influence of intrinsic characteristics and doping amount of CSLSs on LICs performance. In addition, a summary and outlook are conducted, aiming to provide the essential basic knowledge and guidance for developing a new pre‐lithiation technology.