An anode-free Li metal cell with replenishable Li designed for long cycle life

Pit corrosion of Li during stripping is an important factor responsible for poor Li cycling efficiency, a metric that determines its cycling life. When excess Li is present, it has been observed that Li tends to strip in a non uniform fashion, forming pits that extend well past the theoretical Li depth that inevitably lead to the formation of electronically isolated dead Li particles. In this work, a novel cell with replenishable Li is shown to inherently mitigate the formation of this dead Li, as a direct result of a design in which the intrinsically more homogenous stripping behavior of anode-free cells are combined with a replenishable limited Li reservoir. These novel cells (Li vertical bar Cu parallel to LiFePO4) exhibit 25% and 34% higher cumulative capacities than the conventional cells (Cu vertical bar Li parallel to LiFePO4) in carbonate and ether electrolytes, respectively, enabling a significant increase in cycle life without impacting energy density. This improvement strategy represents a new direction in Li metal battery improvement, in which improved cycling can be achieved regardless of electrolyte chemistry.

Automated summary

A novel cell design with replenishable Li is shown to mitigate the formation of dead Li during stripping, resulting in significantly higher cumulative capacities in carbonate and ether electrolytes compared to conventional cells, without impacting energy density. This improvement strategy represents a new direction in Li metal battery enhancement, achieving improved cycling regardless of electrolyte chemistry.