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

Abstract

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_x LM_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_x LM_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_0.6 Co_0.2 Mn_0.2 O₂ (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_0.8 Co_0.1 Mn_0.1 O₂ (NCM₈₁₁ ) further raises the energy density to 1732 Wh L^-1 and 514 Wh kg^-1 .