Binding Li₃PO₄ to Spinel LiNi0.5Mn1.5O₄ via a Surface Co‐Containing Bridging Layer to Improve the Electrochemical Performance

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Coating the surface of cathode materials with Li 3 PO 4 to improve the cycling performance is commonly practiced; however, obtaining an effective and uniform coating of Li 3 PO 4 on cathode materials is extremely difficult due to the lack of strong bonds between them. Herein, this issue is solved by coating the surface of LiNi 0.5 Mn 1.5 O 4 with Li 3 PO 4 via a novel hydrothermal method. It is shown that a uniform Li 3 PO 4 surface coating can only be obtained by introducing a small amount of additional metal ions, such as Co, in the starting solution. X‐ray photoelectron microscopy combined with scanning transmission electron microscopy reveals that the Co ions diffuse into the 16c sites of the surface of the spinel LiNi 0.5 Mn 1.5 O 4 structure, making the surface layer act as a bridging layer that connects olivine Li 3 PO 4 with bulk spinel LiNi 0.5 Mn 1.5 O 4 . The high‐voltage LiNi 0.5 Mn 1.5 O 4 half‐cell with the optimal Li 3 PO 4 coating shows a discharge capacity retention of 95.8% after 50 cycles at 55 °C, compared with the only 81.1% discharge capacity retention of the bare counterpart.