Understanding Ostwald Ripening and Surface Charging Effects in Solvothermally-Prepared Metal Oxide-Carbon Anodes for High Performance Rechargeable Batteries

Metal oxides synthesized by the solvothermal approach have widespread applications, while their nanostructure control remains challenging because their reaction mechanism is still not fully understood. Herein, it is demonstrated how the competitive relation between Ostwald ripening and surface charging during solvothermal synthesis is crucial to engineering high-quality metal (oxide)-carbon nanomaterials. Using SnO2 as a case study, a new type of hollow SnO2-C hybrid nanoparticles is synthesized consisting of core-shell structured SnO2@C nanodots (which has not been previously reported). This new anode material exhibits extremely high lithium storage capacity of 1225 and 955 mAh g(-1) at 200 and 500 mA g(-1), respectively, and excellent cycling stability. In addition, full-battery cells are constructed combining SnO2-C anode with Ni-rich cathode, which can be charged to a higher voltage compared to commercial graphite anode and still demonstrate extraordinary rate performance. This study provides significant insight into the largely unexplored reaction mechanism during solvothermal synthesis, and demonstrates how such understanding can be used to achieve high-performance metal (oxide)-C anodes for rechargeable batteries.