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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