High energy lithium ion battery electrode materials; enhanced charge storage via both alloying and insertion processes

• Direct and continuous hydrothermal synthesis of nano-metal oxide anodes. • The V 0.8 Sn 0.2 O 2 material has a high capacity of 630 mAh g −1 (at 50 mA g −1 ). • The specific capacity is always higher when Sn 4+ is doped into the host material. • The Sn in the anodes acts as electrochemically active alloying component. A series of nano-sized tin-doped metal oxides of titanium(IV), niobium(V) and vanadium(IV), were directly synthesized using a continuous hydrothermal process and used for further testing without any post-treatments. Each of the as-prepared powders was characterized via a range of analytical techniques including powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller surface area measurements, as well as being investigated as an electrode material in a lithium-ion coin cell ( vs lithium metal). All the tin-doped nanomaterials showed higher specific capacities compared to their undoped metal oxide counterparts. The increased charge storage was discussed to originate from the electrochemical activation of the tin dopant as an alloying material. Overall, this work presents a reliable method of combining stable insertion materials with high capacity tin alloying materials under scaled-up conditions.