Retarding Phase Transformation During Cycling in a Lithium- and Manganese-Rich Cathode Material by Optimizing Synthesis Conditions

Li-rich layered oxides with superior energy density have become appealing alternative cathode materials for next-generation lithium-ion batteries. However, they still suffer from voltage decay and irreversible capacity loss due to an undesirable phase transition. Normally, the phase transition is caused by the reduction of Mn ions and migration of the transition metals. In order to address this issue, we herein report a facile and efficient strategy to fabricate a well-structured Li-rich layered Li _1.2 Ni _0.13 Co _0.13 Mn _0.54 O ₂ by an optimized sol-gel method. Experimentally we find that the as-synthesized layered oxide delivers a high initial discharge capacity as high as 279 mAh g ⁻¹ at 0.1 C and remains a capacity of 250 mA g ⁻¹ after 100 cycles when used as a cathode for lithium-ion batteries. Mn L-edge and O K-edge soft X-ray absorption spectra reveal that the reduction of Mn ions and the migration of transition metals have been well mitigated.