Superionic Conductor Enabled Composite Lithium with High Ionic Conductivity and Interfacial Wettability for Solid-State Lithium Batteries

The urgent demand for high energy and safety batteries has generated the rapid development of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) type solid-state lithium metal batteries. However, severe dendritic lithium growth, which is caused by poor interfacial contact of the Li/LLZTO interface and loss of electrical contact during cycles due to low intrinsic Li+ diffusion coefficient of lithium, greatly hampers its practical application. Here, from the point of view of reducing surface tension and improving ion diffusion of lithium, a composite lithium anode (CLA) with high wettability and ion diffusion coefficient is prepared by adding GaP into molten lithium, thus strengthening the CLA/LLZTO interface even in cycling. As envisioned, compared to pure lithium, CLA presents lower surface tension, larger adhesion work, and higher ion diffusion coefficient, ensuring close contact of the CLA/LLZTO interface. Therefore, the assembled symmetric cells exhibit a low area specific resistance of 4.5 Omega cm(2), a large critical current density of 2.5 mA cm(-2), and ultra-long lifespan of 5700 h at 0.3 mA cm(-2) at 25 degrees C. Meanwhile, full cells coupled with LiFePO4 cathode show a high-capacity retention of 97.32% after 490 cycles at 1C. This work provides a new solution to the interfacial challenges of solid-state lithium-metal batteries.