Ketomalonate‐Based Lithium Replenishment Reagents for Lithium‐Ion Batteries with Stable Electrode Structure

Abstract The loss of active lithium during the initial charge process significantly reduces both the energy density and cycle life of lithium‐ion batteries. Cathode lithium replenishment is a promising alternative to lithium metal‐based prelithiation; however, the development of efficient cathode replenishment agents remains limited. Organic lithium replenishment agents offer advantages over inorganic counterparts, including superior air stability, abundant resources, and minimal solid residue after oxidation, providing high specific capacity comparable to lithium metal after degassing. Nevertheless, there is a need for diverse and effective organic agents. Herein, ketomalonate‐based organic lithium replenishment agents: dilithium ketomalonate (DLMT) and tetralithium ketomalonate (TLMT) with uniform spherical particles of ≈1 µm are developed. Both DLMT and TLMT demonstrate high lithium replenishment capacities and excellent compatibility with standard battery manufacturing processes. Their complete decomposition, coupled with uniformly distributed pores, preserves the structural integrity of the cathode and ensures stable electrochemical performance. Incorporating these agents into cathodes led to a 20.5% improvement in capacity retention after 500 cycles for LFP||Gr full cells and increased energy density by 5.7% for LFP||Gr and 7.2% for LMFP||Gr cells. The design of these novel sacrificial salts, emphasizing stability and high lithium replenishment efficiency, underscores their potential in high‐performance lithium‐ion batteries.