Improvement of Electrochemical Performance of Nickel Rich LiNi0.8Co0.1Mn0.1O2 Cathode by Lithium Aluminates Surface Modifications

Ni-rich layered compounds are very promising cathodes for lithium ion batteries whose surface modifications are normally required. As excellent lithium-conducting solid electrolytes lithium aluminates such as LiAlO2 are expected to have an important role to play as a candidate for surface modifications. Here, Ni-rich layered LiNi0.8Co0.1Mn0.1O2 (NCM) coated by lithium aluminates with different nominal weight percentages was prepared using a sol-gel method. Lithium aluminates are found to be a mixture of major LiAlO2 and minor Li5AlO4. The coatings almost have no influence on the size and morphology of NCM particles, and however favor the order degree of structure and change the surface states. The electrical conductivity and charge transfer resistance can be optimized by controlling the amount of lithium aluminates. The cycling stability at low rates such as 1 C tends to increase with the amount of lithium aluminates whereas the rate capability can be achieved at certain amount, which is probably related to the enhancement of electrical conductivity and the improved surface protection against the erosion by electrolyte. This study reveals that the performances of NCM can be significantly improved and tailored by controlling the amount of lithium aluminates.