In Situ Replenishment of Formation Cycle Lithium‐Ion Loss for Enhancing Battery Life

Abstract In situ replenishment of formation cycle lithium‐ion loss is considered for the development of longer‐lasting rechargeable batteries, containing a thin lithium reservoir‐electrode to mitigate the formation cycle capacity loss. Synchronized lithium and lithium‐ion batteries (SLLIB) deliver specific charge‐discharge capacities of 147/145 mAh g –1 for mesocarbon microbeads (MCMB) versus LiFePO 4 and 186/171 mAh g –1 for C‐Si versus LiNi 1/3 Mn 1/3 Co 1/3 O 2 at 0.2 C. The energy‐reduced cells (due to solid electrolyte interface (SEI) formation) are replenished and achieved an increased energy density of 455 Wh kg –1 with retained flat‐voltage profile for SLLIB–MCMB versus LiFePO 4 and 576 Wh kg –1 for SLLIB–C‐Si versus LiNi 1/3 Mn 1/3 Co 1/3 O 2 through Li + ion in situ reservoir replenishment from the reservoir‐electrode to the MCMB/C‐Si anode. Furthermore, reserve mode cycling process delivers charge‐discharge capacities of 126/124 mAh g –1 for SLLIB–Li versus LiFePO 4 and 137/136 mAh g –1 for SLLIB–Li versus LiNi 1/3 Mn 1/3 Co 1/3 O 2 at 0.2 C, associated with the Li + ion transportation between reservoir‐electrode and LiFePO 4 /LiNi 1/3 Mn 1/3 Co 1/3 O 2 cathode, confirmed by the Li + ion diffusion path through MCMB and C‐Si electrodes, using EIS analysis. Ultimately, the in situ reservoir replenishment, replenished cycling and reserve mode cycling processes of SLLIB leads to enhanced battery life.