TiO2 Nanoparticles Assisted LiNbO3-Coated LiNi0.8Co0.1Mn0.1O2 Cathode for Lithium-Ion Batteries

Ni-rich layered-oxide cathode materials (NCM) are widely recognized for their high capacity and low cost, so that they have become the most promising cathode materials, but the low cycle performance limits their application. Therefore, LiNbO3 with high Li+ conductivity was considered as a coating design for NCM. However, the traditional LiNbO3 wet coating method adopts an expensive Nb source to be prepared. Herein, we first prepared LiNbO3 using niobium hydroxide as a Nb source to replace niobium ethoxide and designed a coating strategy that nano-TiO2 as a carrier to fulfill LiNbO3 coated on LiNi0.8Co0.1Mn0.1O2(NCM811). The coating strategy promotes Li+ conductivity between the cathode particles and helps to shield the contact between the cathode and electrolyte. Moreover, the high specific surface area of nano-TiO2 was used to control the coating size of LiNbO3. At 700 °C sintering temperature, a slight amount of the Ti element was doped into LiNbO3 to further improve its ionic conductivity. Thus, 1 wt % TiO2 and LiNbO3-modified NCM811 exhibited 25 mAh g–1 capacity improvement (at 1 C, 25 °C) for liquid lithium-ion battery, then showed 24.7 and 49.1 mAh g–1 capacity improvement (0.2 and 1 C, respectively) and higher capacity retention (79.52% vs 58.60% for bare NCM811 after 100 cycles) for PVDF-based solid-state batteries.