Boosting the cycle and rate performance of Li1.2Mn0.54Ni0.13Co0.13O2 via single-crystal structure design

Lithium-rich layered oxides (LROs) are regarded as promising cathode materials to build high-energy-density lithium-ion batteries (LIBs). However, conventional polycrystalline LROs suffer from irreversible structure changes and slow interfacial kinetics, leading to poor cycle and rate performance. Here we propose a polyvinylpyrrolidone (PVP)-assisted co-precipitation method to prepare single-crystal LRO (Li1.2Mn0.54Ni0.13Co0.13O2) nanosheets. PVP can adsorb on a specific crystal plane during precursor formation to obtain ideal nanosheet morphology. This method is simple, low-cost and easy to scale up. The prepared single-crystal nanosheets feature continuous lattice and no grain boundary inside, which shorten the path of Li+ intercalation/deintercalation and improve the electrode reaction kinetics. The single-crystal structure also inhibits the irreversible phase transformation from the layered phase to the spinel phase and the formation of cracks owing to suitable particle size, stabilizing the layered structure. As a result, the prepared single-crystal Li1.2Mn0.54-Ni0.13Co0.13O2 nanosheets deliver a reversible capacity of 254.5 mA h g−1 at a rate of 0.1 C and good cycling stability with a capacity retention of 71.9% after 1000 cycles at a high rate of 5 C. This work provides a facile method to prepare nano-sized single-crystal LRO materials for improving the cycle and rate performance of LIBs.