Coupling alloyed lean lithium anodes with PIM-1-blended PEO electrolytes synergistically promotes reversible Li stripping/deposition reactions for all-solid-state lithium-metal batteries

All-solid-state lithium batteries with lean (ultrathin) lithium anodes and polymer-based electrolytes e.g., polyethylene oxide (PEO), can potentially offer high energy density, reduced processing cost and improved mechanical contact at electrolyte-electrode interfaces. The non-uniform lithium deposition and inadequate mechanical strength of PEO, however, tend to cause deactivated lithium and short-circuiting by Li dendrites over lithium deposition/stripping cycles; these issues become more aggravated with lean Li anodes due to the more severe volume changes. Herein, we construct a more mechanically and chemically stable lithium-electrolyte interface by coupling alloyed lean Li anodes (<50 μm) with PEO electrolytes blended with polymers of intrinsic porosity (PIMs). The lean Li anode is fabricated by a facile and scalable cold-rolling method, which leads to a uniformly alloyed lithium anode permitting epitaxial Li deposition. Meanwhile, PIM reinforces the mechanical strength of the PEO composite electrolyte, reducing the likelihood of dendrite formation/penetration. Importantly, the introduction of both GaInSnZn and the first-generation PIM has been found to reduce the interfacial charge transfer resistance via modifying the composition of solid-electrolyte interphase. The resulting full cells with lithium iron phosphate cathodes exhibit a high specific capacity of ∼160 mAh/g, i.e., ∼0.6 mAh/cm² with excellent retention of 93.1 % at 120 cycles.