Surface Modification of Li 1.144 Ni 0.136 Co 0.136 Mn 0.544 O 2 by Hybrid Protection Layer with Enhanced Rate Capability

Overlithiated oxide (OLO) materials have received great attention because of their higher recharge capacity (>250 mA h g −1 ) than that of commercial Li‐ion cathode materials. However, they still have some problems such as poor cyclic stability and rate capability. In this study, La(PO 3 ) 3 is coated on Li 1.144 Ni 0.136 Co 0.136 Mn 0.544 O 2 by the dry coating method. The results indicate that 1.0 wt% La(PO 3 ) 3 –coated Li 1.144 Ni 0.136 Co 0.136 Mn 0.544 O 2 delivers a remarkably high rate capability, with a discharge capacity of 163 mA h g −1 even at 5 C, and an excellent cycling performance of 193 mA h g −1 after cycling 100 times at 1 C. The enhanced electrochemical performance comes from the formation of a hybrid protection layer mainly containing Li, La, P, and O (LLPO), which uses residual alkali compounds, LiOH and Li 2 CO 3 , as the lithium source and reacts with La(PO 3 ) 3 . LLPO can not only protect the Li‐rich cathodes from contacting the electrolyte directly, but also reduce the charge transfer resistance. More importantly, it can serve as a Li + conductor, which is beneficial for elevation of the rate capability.