Regulation of Extra Li Inventory in Anode-Free Lithium Metal Batteries by Li-Rich Layered Oxide Cathode Materials

Li-rich layered oxide (LRO) cathode material is utilized in anode-free Li metal batteries to provide extra Li inventory, compensating for the constant Li loss during cycling. The Li compensation mechanism of LRO in the anode-free system is elucidated by exploring the reversible/irreversible Li consumption behaviors. Moreover, the relationship between cathode areal capacity, Li inventory, and the cycling performance of the Cu||LRO cell is quantitatively analyzed. The well-designed Cu||LRO anode-free cell demonstrates 51% capacity retention after 60 cycles at a practical areal capacity of 5.0 mAh cm^-2, overwhelming the 0.6% capacity retention for Cu||NCM523. Further optimization with an artificial anode protection layer and a fully fluorinated electrolyte enhances the capacity retention of Cu||LRO to 61.4% and 71.5% after 60 cycles, respectively. Combining its low initial Coulombic efficiency and high specific energy, the LRO cathode shows great prospects in the future development of high energy and long lifespan anode-free Li metal batteries.