Synergistic effects of heterostructures can improve electrochemical properties of electrode materials. Herein, core-shell heterogeneous structures of V2O5@MV6O15 (M = Na, K) nanoparticles were designed and successfully synthesized through a facile "semi-solid" method. V2O5@NaV6O15 nanoparticles showed a high discharge capacity of 140 mAh g(-1) at 200 mA g(-1) which retained 94.9% after 200 cycles, higher than those of V2O5 nanoparticles (116.1 mAh g(-1) and 58%). Moreover, through an advanced in-situ XRD technology, the synergistic effect of buffering and smoothing Li+ diffusion from MV6O15 outer layer was revealed. This facile strategy could be widely applied to improve the electrochemical performances of other electrode materials. (C) 2017 Elsevier Ltd. All rights reserved.