High Energy Density Lithium Ion Batteries with Iron- and Nickel-Substituted Lithium-Rich Layered Oxide Cathode

Abstract

Large-capacity 8 Ah-class cells were fabricated using iron- and nickel-substituted lithium-rich layered manganese oxides (Li1.23Mn0.46Fe0.15Ni0.15O2) cathodes, anodes consisting of a mixture of Si and SiO, and high-voltage resistant electrolyte based on fluorinated solvents (1 M LiPF6 (Fluoroethylene carbonate (FEC)/diethyl carbonate (DEC)/1, 1, 2, 3, 3, 3-hexafluoropropyl difluoromethyl ether (HDE)). The cells had a capacity of 8.39 Ah and average voltage of 3.02 V. Their energy density was 271 Whkg−1 and output power density was 1.1 kWkg−1. From the investigation of 35 mAh-cells, the capacity retention of cells with 1 M LiPF6 FEC/DEC/HDE and 1 M LiPF6 ethylene carbonate (EC)/DEC solution became 81% and 72% after 30 cycles, respectively, which implies that the decomposition of the LiPF6 electrolyte was suppressed by the FEC/DEC/HDE. We believe that the ability to fabricate a 270 Whkg−1 cell will contribute to the development of next-generation storage devices.