A high-energy-density and long-life initial-anode-free lithium battery enabled by a Li2O sacrificial agent

Equipped with a fully lithiated cathode with a bare anode current collector, the anode-free lithium cell architecture presents remarkable advantages in terms of both energy density and safety compared with conventional lithium-ion cells. However, it is challenging to realize high Li reversibility, especially considering the limited Li reservoir (typically zero lithium excess) in the cell configuration. In this study we have introduced Li2O as a preloaded sacrificial agent on a LiNi0.8Co0.1Mn0.1O2 cathode, providing an additional Li source to offset the irreversible loss of Li during long-term cycling in an initial-anode-free cell. We show that O2− species, released through Li2O oxidation, are synergistically neutralized by a fluorinated ether additive. This leads to the construction of a LiF-based layer at the cathode/electrolyte interface, which passivates the cathode surface and restrains the detrimental oxidative decomposition of ether solvents. We have achieved a long-life 2.46 Ah initial-anode-free pouch cell with a gravimetric energy density of 320 Wh kg–1, maintaining 80% capacity after 300 cycles. Anode-free batteries offer high-energy prospects but suffer from poor cycling stability due to limited lithium sources. Here, the authors preload lithium oxide onto a high-energy cathode in initial-anode-free cells, which substantially improves the cyclability while maintaining high energy density.