Lithium nickelate electrodes with enhanced high-temperature performance and thermal stability

Lithium nickelate is an attractive positive electrode material for lithium ion batteries because of its large capacity at ambient temperatures. However, highly delithiated LiNiO2 (e.g. Li0.2NiO2) shows undesirable exothermal heat at 200°C. We found another issue of LiNiO2 in this study, namely poor reversibility at 40°C. To overcome these disadvantages, we introduced cobalt, manganese, and titanium as partial substituents for nickel. Cobalt substitution was effective in improving the reversibility at 40°C. The exothermal decomposition of the delithiated compounds was suppressed by using manganese and titanium as substituents. We found doubly substituted nickelate LiNi0.8Co0.1Ti0.1O2 to be the most promising in terms of large capacity (190 mA h g−1), enhanced high-temperature performance, and improved thermal stability.