Lithium-rich layered oxides are widely considered as the most promising candidate for high energy density cathode in lithium-ion batteries (LIBs) due to their extraordinary capacity. However, cycle instability, poor rate capability and voltage decay impede their practical applications, which are caused by oxygen release and phase transformation during cycling. In this work, an ultrathin spinel Li₄Ti₅O₁₂ (LTO) coating acting alike a “lithium ion pump” is built on the surface of lithium-rich layered oxides Li_1.2Ni_0.2Mn_0.6O₂ (LLNMO) through solvothermal method. It is identified that spinel LTO and layered LLNMO phases display heteroepitaxial structure resulting in reduction of oxygen loss, phase transformation, capacity decline and voltage fading. The cathode with heteroepitaxial structure demonstrates an acceptable initial coulombic efficiency up to 87.7% (only 79.8% for LLNMO), highly competitive cycling stability (97.9% capacity retention at 0.1C after 100 cycles), minimal voltage decay of 1.22 mV cycle⁻¹ and excellent rate capability (171.5 mAh g⁻¹ at 10C). The supreme electrochemical performances suggest that epitaxial spinel LTO coating can effectively stabilize oxygen framework and the layered structure on the surface of lithium-rich layered oxides for modification of high-capacity cathode in next generation LIBs.

由于其非凡的容量，富锂层状氧化物被广泛认为是锂离子电池（LIB）中高能量密度正极的最有希望的候选材料。然而，循环不稳定、倍率能力差和电压衰减阻碍了它们的实际应用，这是由循环过程中的氧释放和相变引起的。在这项工作中，在富锂层状氧化物 Li _1.2 Ni _0.2 Mn _0.6 O ₂的表面上构建了超薄尖晶石 Li ₄ Ti ₅ O ₁₂ (LTO) 涂层，其作用类似于“锂离子泵”(LLNMO) 通过溶剂热法。确定尖晶石 LTO 和分层 LLNMO 相显示异质外延结构，导致氧损失减少、相变、容量下降和电压衰减。具有异质外延结构的正极表现出可接受的初始库仑效率高达 87.7%（LLNMO 仅为 79.8%）、极具竞争力的循环稳定性（100 次循环后 0.1C 下容量保持率为 97.9%）、最小电压衰减为 1.22 mV 循环^-1和优异的倍率性能（171.5 mAh g ^-1 在 10 摄氏度）。优异的电化学性能表明，外延尖晶石 LTO 涂层可以有效地稳定富锂层状氧化物表面的氧骨架和层状结构，用于修饰下一代 LIB 中的高容量阴极。