Cathode materials with higher energy density than layered oxide materials are required for future demands of vehicle electrification. Disordered rock-salt Li-excess structures, such as Li₃NbO₄, have been demonstrated to achieve capacities of greater than 300 mAh/g reversible capacities at elevated temperatures. The high capacity is believed to be due to reversible redox chemistry of the oxide anions. This new class of high energy cathode materials provides an opportunity for a step change increase in cell level energy density. However, improvements are still required in material conductivity and stability. In this presentation, we demonstrate material improvements which enable high specific capacity at room temperature and extended cycle life.