Material design concept for Fe-substituted Li2MnO3-based positive electrodes

Fe-substituted Li2MnO3 (Li1+x(FeyMn1−y)1−xO2, 0 ≤ x ≤ 1/3, 0.3 ≤ y ≤ 0.7) was synthesized using a combination of coprecipitation, hydrothermal, and heat-treatment methods. It exhibits high initial specific capacity greater than 200 mAh g−1 and small capacity, which fades up to the 50th cycle (>150 mAh g−1 at the 50th cycle) under electrochemical cycle testing at 60 °C. The attractive electrode properties appeared by controlling the chemical composition (x > 0.05, 0.3 ≤ y ≤ 0.5) and high specific surface area (>20 m2 g−1). The Fe-substituted Li2MnO3 is an attractive candidate as a novel 3 V-class positive electrode material.