Synthesis of Hollow Three-Dimensional Channels LiNi0.5Mn1.5O4 Microsphere by PEO Soft Template Assisted with Solvothermal Method

A appropriate size with three-dimension (3D) channels for lithium diffusion plays an important role in constructing high-performing LiNi0.5Mn1.5O4 (LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li+ intercalation/deintercalation. In this work, an efficient method for designing the hollow LNMO microsphere with 3D channels structure by using polyethylene oxide (PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g−1 at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.