Ion-regulating Hybrid Electrolyte Interface for Long-life and Low N/P Ratio Lithium Metal Batteries

Practical lithium metal batteries (LMBs) require full and reversible utilization of limited metallic Li anodes at a solid/quasi-solid electrolyte condition. This leads to a challenging issue, i.e., how to create compatible interphases to regulate interfacial ionic transport and protect the reactive metal. Herein, to address this issue, we report a robust cellulose-based composite gel electrolyte (r-CCE) capable of stabilizing ion deposition via compositing bacterial cellulose (BC) skeleton with Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) particles. Benefiting from the decoupled segment structure of cellulose and additional ionic channels of LLZTO, r-CCE not only achieves high ionic conductivity (1.68 × 10⁻³ S/cm) with a remarkable Li-ion transfer number (∼0.92) and a wide window of electrochemical stability (∼5.3 V), but also helps stabilize the Li anode. Utilizing ultrathin lithium metal anodes (15 μm), ultra-stable symmetric Li/Li cells that are armed with r-CCE demonstrate a highly stable plating/stripping process. Furthermore, a high areal capacity of ∼4.2 mAh/cm², and 100 cycles with improved stability of the full Li metal batteries with n/p ratio of ∼0.74 are achieved.