Surface-disordered and oxygen-deficient LiTi2-xMnx(PO4-y)3 nanoparticles for enhanced lithium-ion storage

•LiTi2-xMnx(PO4-y)3 nanoparticles have been synthesized by a hydrothermal reaction.•The disordered surface is thought to be triggered by the reduction induced by Ar/H2.•The reduced species increase the Li-ion diffusion coefficient inside the particle.•The disordered surface and the doping improve the electrochemical performances.

Disordered surface of anode materials accompanied by oxygen vacancies, has been developed as an efficient strategy to promote their charge-transfer kinetics and then improve their electrochemical properties. It is rarely explored for cathode materials before. Here, LiTi2-xMnx(PO4-y)3 nanoparticles with a disordered surface and oxygen vacancies, are synthesized by a hydrothermal method following with an annealing in Ar/H2. Their disordered surface and heteroatom doping by reduced Mn/Ti species, have been supported by HRTEM images, XPS and EDS spectra. After 120 cycles at 0.2 C, these nanoparticles still deliver a capacity of 127 mAh g−1, much higher than the product without any doping, and that without a disordered surface. Even after 500 cycles, the capacity is still at 101 mAh g−1 for 5 C or at 71 mAh g−1 for 20 C. These results could be attributed to the reduced charge-transfer resistance caused by disordered surface, and the enhanced lithium-diffusion induced by doping.

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