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

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Anode-free lithium metal batteries (LMBs) offer high energy density but suffer from lithium loss during cycling.
• Li-rich layered oxides (LROs) are explored as cathode materials to provide a Li reservoir, compensating for this loss.

Purpose of the Study:

• To elucidate the Li compensation mechanism of LROs in anode-free LMBs.
• To quantitatively analyze the relationship between cathode properties, Li inventory, and cycling performance.
• To demonstrate the potential of LROs for high-performance anode-free LMBs.

Main Methods:

• Investigating reversible and irreversible Li consumption behaviors in LRO cathodes.
• Quantitative analysis of cathode areal capacity, Li inventory, and cycling performance in Cu||LRO cells.
• Evaluating the impact of artificial anode protection layers and fluorinated electrolytes on cell performance.

Main Results:

• The designed Cu||LRO anode-free cell achieved 51% capacity retention after 60 cycles at 5.0 mAh cm^-2, significantly outperforming Cu||NCM523 (0.6% retention).
• Optimization with an artificial anode protection layer improved retention to 61.4%.
• Further enhancement using a fully fluorinated electrolyte resulted in 71.5% capacity retention after 60 cycles.

Conclusions:

• LRO cathodes effectively compensate for Li loss in anode-free LMBs through their unique Li compensation mechanism.
• Optimized LRO-based anode-free cells demonstrate superior cycling stability and capacity retention.
• LROs show significant promise for developing next-generation high-energy and long-lifespan anode-free lithium metal batteries.