500 Wh kg⁻¹ Class Li Metal Battery Enabled by a Self-Organized Core–Shell Composite Anode

Lithium (Li) metal offers the highest projected energy density as a battery anode, however its extremely high reactivity induces dendrite growth and dead Li formation during repeated charge/discharge processes, resulting in both poor reversibility and catastrophic failure. Approaches reported to date often seek to suppress dendrites formation at the expense of energy density. Here, a strategy that resolves the above conflict and achieves a dendrite-free and long-term reversible Li metal anode is reported. A self-organized core–shell composite anode, comprising an outer sheath of lithiated liquid metal (Li_xLM_y) and an inner layer of Li metal, is developed, which posesses high electrical and ionic conductivity, and physically separates Li from the electrolyte. The introduction of Li_xLM_y not only prevents dendrite formation, but also eliminates the use of copper as an inert substrate. Full cells made of such composite anodes and commercially available LiNi_0.6Co_0.2Mn_0.2O₂ (NCM₆₂₂) cathodes deliver ultrahigh energy density of 1500 Wh L⁻¹ and 483 Wh kg⁻¹. The high capacity can be maintained for more than 500 cycles, with fading rate of less than 0.05% per cycle. Pairing with LiNi_0.8Co_0.1Mn_0.1O₂ (NCM₈₁₁) further raises the energy density to 1732 Wh L⁻¹ and 514 Wh kg⁻¹.