Ni/Mn_3O_4/NiMn_2O_4@RGO空心微球负极的制备及其储钠性能（英文）

Ni/Mn_3O_4/NiMn_2O_4 Double-Shelled Hollow Spheres Embedded into Reduced Graphene Oxide as Advanced Anodes for Sodium-Ion Batteries

采用溶剂热法制备前驱体,后经350°C热处理,首次合成了空心结构的NiMn_2O_4微球以及不同含量氧化石墨烯包覆的Ni/Mn_3O_4/NiMn_2O_4@RGO复合材料.电化学性能测试表明,复合负极材料中,含25wt%还原氧化石墨烯的材料储钠性能最佳,其在50 m A·g^(-1)电流密度下,100次循环后放电比容量保持在187.8 m Ah·g^(-1),且800 m A·g^(-1)电流密度下的可逆容量高达149.9 m Ah·g^(-1),明显优于NiMn_2O_4及其他石墨烯基复合材料.研究指出,复合材料性能的提升得益于空心微球和还原的氧化石墨烯构成的特殊结构,一方面缩短了电子/离子传输距离,缓解了体积效应,另一方面高导电网络有效增强了活性物质利用率.

Delicately building the unique nanocomposite with the combination of hollow structure and reduced graphene oxide(rGO) is highly desirable and still remains a great challenge in the field of energy conversion and storage. In this work,Ni/Mn3O4/NiMn2O4 double-shelled hollow spheres coated by rGO(denoted as R-NMN) have been successfully synthetized via one-step rapid solvothermal treatment followed by subsequent annealing for the first time. Served as anodes for sodium ion batteries(SIBs), the R-NMN composite containing 25 wt% rGO exhibits a high discharge capacity of 187.8 m Ah·g^-1 after 100 cycles at 50 m A·g^-1 in the potential range between 0.01 V and 3.0 V(vs. Na+/Na). When cycled at different current densities of 100, 200, 400, and 800 m A·g^-1, the nanocomposites deliver the reversible capacities of 213.45, 192.9, 171.7, and 149.9 m Ah·g^-1, respectively, indicating a satisfactory rate capability. Our conclusions reveal that the significant improvement in electrochemical performance is mainly attributed to the enhanced conductivity, reduced ion diffusion distance and suppressed volume fluctuation. The modification strategy proposed in this study can be extended to the design of other electrode materials for sodium storage and beyond.