Extended Cycle Life in Lithium‐Ion Batteries through Lithium Supplementation from Li2C4O4@SiO2 Microcapsules

The formation of a solid electrolyte interphase (SEI) in lithium‐ion batteries consumes active lithium ions, resulting in loss of capacity and decreased cycle life. Most prelithiation methods only address the initial lithium depletion by compensating with a source of lithium ions, overlooking the ongoing lithium consumption through continuous degradation processes. In this study, Li 2 C 4 O 4 @SiO 2 microcapsules are presented, in which Li 2 C 4 O 4 serves as an additional source of lithium ions and the porous SiO 2 shell prevents unwanted catalytic reactions, ensuring sustained lithium availability throughout the cycling. The microcapsules are synthesized using a wet impregnation method and characterized using various techniques to confirm their structural, morphological, and compositional properties. Ex situ nuclear magnetic resonance (NMR) analysis demonstrated lithium‐ion mobility, and electrochemical tests in full‐cell configurations with graphite and graphite/silicon anodes confirmed improved capacity retention and cycle life. This work highlights the potential of microencapsulated lithium‐ion sources to improve battery performance in various lithium‐ion systems and opens a pathway for battery cells with self‐healing functionality that can be triggered on demand.