Failure mechanism of layered lithium-rich oxide/graphite cell and its solution by using electrolyte additive

• Cyclability of layered lithium-rich oxide/graphite cell depends on cathode performance.
• HF formed from electrolyte decomposition causes the corrosion of aluminum current collector.
• TMSPi is effective for improving cyclability of layered lithium-rich oxide/graphite cell.
• Cathode interphase formed from TMSPi suppresses the electrolyte decomposition.

We report a failure mechanism of layered lithium-rich oxide/graphite cell and a solution to this failure. Charge/discharge tests demonstrate that Li1.2Mn0.54Ni0.13Co0.13O2/graphite full cell fails when it is performed with cycling and this issue can be solved effectively by using an electrolyte additive, tris (trimethylsilyl) phosphite (TMSPi). Further cycling tests on Li/Li1.2Mn0.54Ni0.13Co0.13O2 and Li/graphite half-cells and physical characterizations on the cycled cathode indicate that this failure involves the increased HF concentration and the subsequent corrosion for aluminum current collector of cathode due to the electrolyte decomposition during cycling. TMSPi contributes to the formation of a protective interphase on cathode due to its preferential oxidation compared with the base electrolyte, which suppresses the electrolyte decomposition and the HF formation, preventing aluminum current collector from corrosion.