Plasma-assisted sputter Li3PO4 coating on NCM955 cathodes enhancing high-temperature cycling performances

Nickel-rich layered materials are appealing choices for high energy density future lithium-ion batteries (LIBs), electrochemical instability during the cycle hinders its practical application. Surface coating is one of the most effective ways to deal with this problem. For larger protective regions, coating whole particles have been used more frequently than only for electrodes. In this research, magnetron sputtering is used to directly cover LiNi _0.9Co _0.05Mn _0.05O ₂ composite electrodes with an amorphous Li ₃PO ₄ (LPO) layer. The NCM955 electrode is cycled at 1–10 C at room temperature after a 5 nm thick LPO coating. The NCM955/LPO-2 shows a discharge capacity of 162.5 mAh g ^–1 at 10 C and a high temperature of 50 ^◦C. More remarkably, the LPO-coating also improves the rate capacity, in addition to being superior to the one at room temperature, it also has higher temperature rate capability. Superior chemical robustness and Li ⁺ conductivity of the LPO, which acts as a protective layer and a uniform Li ⁺ transport layer.