Multicomponent solid-solution alloy negative electrode for Li-metal batteries.

Abstract

Lithium metal batteries possess the high theoretical specific energy owing to the high theoretical specific capacity of lithium metal. However, practical implementations necessitate a reduction in both lithium mass fraction and lithium utilization within the negative electrode to enhance cycling life and suppress dendrite formation, resulting in a practical reversible capacity of only 30 - 50% of the theoretical value. Herein, we present a lithium metal-based multicomponent solid-solution alloy comprising approximately 90 wt.% lithium, with equal atomic ratios of cadmium, silver, magnesium, and aluminium constituting the remaining 10 wt.%. The increased mixing entropy enables high lithium-atom diffusivity, facilitating inward lithium transport into the metal foil rather than the surface deposition typically observed in conventional lithium metal negative electrodes, while simultaneously promoting a thermodynamically stable (110) crystal facet. These factors collectively yield a dendrite-free negative electrode with a reversible specific capacity of 3100 mAh g^-1. One-ampere-hour pouch cells employing this negative electrode and a LiNi_0.8Co_0.1Mn_0.1O₂ positive electrode achieve an specific energies of 385 Wh kg^-1 (based on the total mass of the pouch cell) with 82% capacity retention over 600 cycles. This achievement highlights the potential of this alloy negative electrode to enable safe and durable high-energy-density lithium metal batteries for practical applications.