Bifacial leaf-inspired tailored design for asymmetric quasi-solid-state electrolytes enabling high-performance lithium metal batteries

Quasi-solid-state electrolytes (QSSEs) synergistically integrate the merits of solid and liquid electrolytes, offering exceptional promise for high-performance lithium metal batteries (LMBs). However, achieving concurrent high ionic conductivity, mechanical robustness, and favorable interfacial characteristics remains fundamentally challenging for QSSEs. Inspired by bifacial leaf architecture, we develop an asymmetric QSSE (AQSE) featuring spatially differentiated functionality. The cathode side incorporates polyimide (PI) matrices composited with in-situ grown ZIF-67 crystals, enhancing electrochemical stability and enabling efficient ion transport through ordered pores. On the anode side, a polydopamine-coated multilayer concave SiO₂ (MLC@PDA) coating concurrently improves mechanical robustness and electrode/electrolyte interfacial compatibility. This tailor-made biomimetic asymmetry yields superior electrochemical performance metrics, including a high ionic conductivity of 3.52 × 10⁻³ S cm⁻¹, a wide electrochemical stability window of 5.06 V, and excellent interfacial properties. In Li−Li symmetric cells, the AQSE maintains stable Li plating/stripping for over 2500 h, while Li−LFP full cells with AQSE exhibit 91 % capacity retention after 1000 cycles at 1 C.