Preparation of Li2MnO3 nanowires with structural defects as high rate and high capacity cathodes for lithium-ion batteries

Abstract

Li2MnO3, as a member of Li-rich and Mn-rich (LMR) layered oxides, has been considered as an appealing candidate for cathode preparation due to its high capacity and high voltage. Nevertheless, its commercialized application has been hindered by its demerits of poor ratability and capacity decay. Meanwhile, structural defects have been proven to influence the electrochemical activities of Li2MnO3. Herein, Li2MnO3 nanowires with varying numbers of structural defects were prepared and measured as cathode materials. rLMO-2 nws with the highest level of oxygen vacancies and the largest amount of Mn3+ were found to exhibit higher specific capacities, higher capacity retention rates, and better rate performances. In order to demonstrate the superiority of nanowire materials with large surface areas, the performance of nanowires materials was compared with that of nanobelt materials. As LIB cathodes within the voltage window of 2.0–4.8 V and at the rate of 0.1C, R-LMO-30 nbs were found to reach the specific capacities of 98.7, 119.1, 137.7, and 146.8 mAh g−1 in the 2nd, 5th, 10th, and 20th cycles, respectively, while rLMO-2 nws delivered the relatively high values of 170.7, 189.4, 196.4, and 162.3 mAh g−1, respectively. The rLMO-2 nws sample also showed an enhanced rate capacity. The superior electrochemical properties of the rLMO-2 sample were associated with the nanowire structure’s large surface area, which could not only activate the Li2MnO3 phase quite easily but also enhance electron and ion transportation properties. This research revealed the influences of morphological control on the formation of surface structural defects in Li-rich layered oxides. And we believe our research findings will be helpful in providing a feasible strategy to enhance the electrochemical performance of Li-rich and Mn-rich layered oxides materials.