Stabilizing Cathode Materials of Lithium-Ion Batteries by Controlling Interstitial Sites on the Surface

Summary Lithium-ion batteries with high energy density are being intensively pursued to meet the ever-growing demand for energy storage. However, the increase in energy density often comes with an elevated instability of electrode materials, causing major concerns about the reliability and safety of lithium-ion batteries. Here, we report a strategy for stabilizing cathode materials by modulating the vacant lattice sites on the particle surface. Using the high-voltage Li[Ni 0.5 Mn 1.5 ]O 4 as an example, we demonstrate that introduction of a 10-nm epitaxial surface layer with Al 3+ in the empty 16c octahedral sites of the spinel Li[Ni 0.5 Mn 1.5 ]O 4 suppresses structural degradation during cycling by increasing the surface stability without interfering with the Li + diffusion around the Al 3+ sites. Control of the Al 3+ concentration in the surface region was shown to be a facile process. The process was shown to stabilize long-term cycling of Li[Ni 0.5 Mn 1.5 ]O 4 to 5 V versus Li + /Li 0 .