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Constructing polycrystalline structure is an effective strategy to improve the electrochemical performance of electrode materials. To enhance the electroactivity of anisotropic VO 2 (M), polycrystalline VO 2 (M) with well-dispersed crystalline zones is successfully synthesized by a facile one-step hydrothermal method, and then their electrochemical performances as an anode of lithium-ion batteries are systematically explored. Results show that the synergistic effect of crystalline zones and amorphous matrices in polycrystalline structure can dramatically activate the anisotropic VO 2 (M) electrode, which contributes to increasing the electroactive zones and facilitating the charge transfer kinetics. Compared with single-crystal VO 2 (M), polycrystalline VO 2 (M) shows the significantly enhanced electrochemical performance, delivering a high reversible capacity of 476 mAhg−1 at 100 mAg−1 after 150 cycles, which is far superior to the theoretical capacity and the reported mixture of VO 2 (M) and VO 2 (B). This work opens up new insights for the activation of anisotropic electrode materials. • Polycrystalline VO 2 (M) with well-dispersed crystalline zones is synthesized. • Synergistic effect of crystalline zones and amorphous matrices is revealed. • The activity of anisotropic VO 2 (M) electrode is dramatically improved. • Polycrystalline VO 2 (M) shows capacity of 476 mAhg−1 at 100 mAg−1 after 150 cycles. [ABSTRACT FROM AUTHOR]

As an indispensable part of lithium-ion batteries (LIBs), the quality of solid-electrolyte interphase (SEI) influences directly the electrochemical performance. α-FeOOH with superior theoretical capacities, low cost, and environmental friendliness has been regarded as a promising anode of LIBs. In this work, we found that the hydroxyl groups on the surface of α-FeOOH bond with organic electrolytes that forming an inferior SEI layer contained excessive ROCO 2 Li, finally causing a poor Li+ transport. Thus, we construct a novel heterostructure of spindle-like α-FeOOH nanorods embedded in mulberry-like Fe 2 O 3 sphere on reduced graphene oxide sheets (F@F/C) based on the dissolution-recrystallization mechanism to optimize the composition of SEI layers. The content of ROCO 2 Li is decreased as expected in the SEI of F@F/C electrode, which diminish the ionic transfer impedance in the interface and provide more alternative diffusion pathways. As expected, the heterostructural hybrid achieves an excellent electrode performance with a reversible capacity about 1800 mAh g−1 at 0.2 A g−1 after 300 cycles. Even cycled at a high current density of 1 A g−1, the hybrid also remains 1050 mAh g−1 after 600 cycles with a capacity decay rate of only 0.005% per cycle. • A heterostructure of spindle-like α-FeOOH nanorods embed in mulberry-like Fe 2 O 3 sphere is rationally constructed. • Embedded architecture optimizes the proportion of Li 2 CO 3 and ROCO 2 Li in SEI to diminish ionic transfer impedance. • Embedded architecture provides more alternative diffusion pathways to improve ionic diffusion kinetics significantly. [ABSTRACT FROM AUTHOR]