Improving electrochemical performance of LiNi_0.9Co_0.05Mn_0.05O₂ cathode material by coating with nano-LiNbO₃ layer

The nano-LiNbO₃ layer coated LiNi_0.9Co_0.05Mn_0.05O₂ (LNbO-LNCMO) cathode material was synthesized by using a facile solid-state reaction method. The starting materials, Ni_0.9Co_0.05Mn_0.05(OH)₂ precursor, lithium hydroxide (LiOH．H₂O), and ∼500 nm niobium pentoxide (Nb₂O₅) powders, were mixed and then one-step sintered at high temperature to obtain the resultant powder. Examinations via SEM/EDS, XPS and FE-TEM revealed a ~10 nm LiNbO₃ layer on the surface of the resultant LNbO-LNCMO. The LNbO-LNCMO showed discharge capacities of 218.6 and 171.8 mAh/g at discharging rates of 0.1 and 5.0 C, respectively. These results improved the corresponding values for a pristine LNCMO sample at 212.3 and 105.1 mAh/g. After 50 charge/discharge cycles, the LNbO-LNCMO retains 93.3 % of its initial capacity, compared with an 80.6 % retention rate for pristine LNCMO. EIS and PITT analyses show that the electronic resistance of LNbO-LNCMO is much lower than that of pristine LNCMO and the higher apparent Li+ ion diffusion coefficients are obtained. The LNbO-LNCMO also show an improved thermal stability over the pristine LNCMO according to DSC analysis. These results confirm that a nano-LiNbO₃ layer on the surface of LNCMO significantly reduces the reactions between electrode materials and electrolytes, which improves electrochemical performance. In this regard, the simple synthesis process with nanoparticle modification offers a promising new approach for the battery industry to fabricate novel cathode materials with high performance.