Shape-Controlled Reversible Li Plating-Stripping for Stable and High-Rate Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries are promising toward high-energy-density power sources with low-cost, but their practical applications are challenged by poor cycling stability and low rate capability. Herein, a shape change-free and lithium-free anode that well controls the reversible Li plating-stripping is reported, which is composed of a highly-ordered hollow ZnO matrix with a surface-coated lithium-phosphorus-oxynitride (LiPON) layer. The ZnO matrix supplies sufficient cavities and lithiophilic sites to facilitate uniform Li plating/stripping within the hollow cavity, while the LiPON layer maintains stable solid-electrolyte interphase from mechanical and electrochemical damage. As a result, lithium is constrained within the cavity and the overall anode shape is effectively controlled during long-term and high-rate cycling. The assembled half-cell stably works at 1.2 mA cm^-2 for 335 cycles with Coulombic efficiency of 98.8%. Without Li pre-deposition, full-cells using modified-LiFePO₄ and LiNi_0.5Co_0.2Mn_0.3O₂ cathodes demonstrate 150-cycles lifespan and high energy density of 617 Wh kg^-1 at 2C rate.