Spinel-related Li2Ni0.5Mn1.5O4 cathode for 5-V anode-free lithium metal batteries

The anode-free lithium metal battery with high voltage LiNi0.5Mn1.5O4 cathode is an excellent Co-free high energy density (ED) system. However, it suffers severely from cycling capacity fading due to no lithium compensation from the anode side. In this study, as against LiNi0.5Mn1.5O4 cathode, Li-rich Li2Ni0.5Mn1.5O4 is proposed, which can smoothly convert into LiNi0.5Mn1.5O4 and release a large amount of Li-ions at the first charge to replace the Li loss in the following cycle, thereby extending the lifespan of the battery without the introduction of inactive components. Using such a Li-rich cathode, the anode-free pouch cell attained 367-Wh kg−1 stack ED and 88% capacity retention (CR) after 50 cycles, with limited electrolyte addition (E/C ratio of 2 g Ah−1). Our work provides a new low-cost strategy to explore high ED Co-free Li metal batteries.