Regulating Li+ Transport Behavior by Cross-Scale Synergistic Rectification Strategy for Dendrite-free and High Area Capacity Polymeric All-Solid-State Lithium Batteries

The inability to effectively inhibit the lithium (Li) dendrite growth is identified as the real culprit hindering the practical application of polyethylene oxide (PEO)-based electrolytes. Herein, a novel PEO composite electrolyte with ion rectifier is developed based on the cross-scale synergistic rectification strategy. At the micro-scale, the array structure of the ion rectifier suppresses the growth of PEO crystals and their distribution in the non-ionic conduction direction through space confinement, alleviating ion-migration crosstalk and enabling polymer chain rectification. Furthermore, the matrix contains abundant copper ions and oxygen-containing groups that inhibit anion conduction and accelerate Li+ migration at the nanoscale, respectively, to achieve ion flow rectification. Implementing this strategy results in a uniform, fast, and stable Li+ migration/diffusion behavior from the electrolyte to anode interface. The critical current density of the PEO electrolyte is increased to 2.5 mA cm−2, indicating a significant improvement in dendrite growth inhibition. Impressively, the composite electrolytes exhibit long-term stability (>4000 h at 0.2 mA cm−2) and ultra-high current-density tolerance (>200 h at 1 mA cm−2). Moreover, the composite electrolytes enable stable cycling of high-area-capacity (3.11 mAh cm−2, 20 mg cm−2) LiFePO4/Li pouch cells, highlighting the importance of this strategy for the practical application of PEO electrolytes.