Stabilized Solid Electrolyte Interface Layer and Regulate the Li⁺ Flux for Dendrite-Free Lithium Metal Batteries

Disordered porous polyolefin separators cannot control the formation of lithium dendrites, which will seriously affect the practical application of lithium metal batteries. In this paper, the polyethylene (PE) separator is modified with CaCO₃ and cobalt phthalocyanine (CoPc). CaCO₃ reacts with the by-products generated during the cycling process, effectively inhibiting the successive generation of by-products, preventing the solid electrolyte interface (SEI) from being constantly destroyed and regenerated, and maintaining the stability of the SEI. Density functional theory (DFT) calculations show that CaCO₃ and CoPc can absorb Li⁺, reduce the solvation degree of Li⁺, promote the rapid and uniform deposition of Li⁺, and realize dendrite-free growth. The results show that Li|CaCO₃@CoPc@PE|Li cell (1 mA cm^-2 cycle for more than 1550 h) and Li|CaCO₃@CoPc@PE|Cu cell (0.25 mA cm^-2 cycle for more than 500 cycles, Coulomb efficiency maintained 96.52%) have excellent cycle stability. In addition, the LiFePO₄|CaCO₃@CoPc@PE|Li cell can still achieve more than 300 cycles at 2C, and the discharge capacity is maintained at 115.19 mAh g^-1, and the capacity retention rate is as high as 98.65%. The CaCO₃@CoPc@PE separator provides a new idea to inhibit dendrite growth.