Li2TiSiO5 receives much interest recently in lithium-ion battery anodes because of its attractive Li-insertion/extraction potential at 0.28 V (vs.Li+/Li),which bridges the potential gap between graphite and Li4TisO12.However,Li2TiSiO5 suffers from the low intrinsic electronic conductivity and sluggish Li-ion transfer kinetics.In this work,we report lithium-ion insertion kinetics of Li2TiSiO5 by Na doping,achieving high-rate capability.Rietveld refinement of X-ray diffraction results reveals that Na doping can enlarge the space of Li slabs,thus reducing the Li-ion transfer barrier and enhancing the Li-ion diffusion kinetics.According to first-principles calculations,Na doping can tune the band structure of Li2TiSiO5 from indirect to direct band,leading to improved electronic conductivity and electrochemical performance.In particular,the Na-doped Li2TiSiO5 (Li1.95Na0.05TiSiO5) electrode exhibits outstanding rate capability with a high capacity of 101 mA h g-1 at 5 A g-1 and superior cyclability with a reversible capacity of 137 mA h g-1 under 0.5 A g-1 over 150 cycles.