asymmetrical distribution of lithium resource. [3,4] On the other hand, sodiumion batteries (SIBs) have attracted great attention due to its abundant sodium resource, low cost, and the similar electrochemical reaction to LIBs, which is considered as the promising battery technology for large-scale energy storage applications. [5,6] But the commercial graphite does not work for SIBs as its interlayers are incapable to accommodate the sodium ions with larger ionic size. [7] As a result, one promising step to make the technological advancements is to develop the novel anode materials with both lithium and sodium storage ability.In this regard, transition metal oxides (M a O b , M = Mn, Fe, Co, Ni, Cu, etc.) based on the conversion reaction mechanism have been widely explored as the potential anode materials for LIBs and SIBs. Compared to graphite, transition metal oxides can provide higher theoretical specific capacity and higher safety, because the higher reaction potential can eliminate the lithium/sodium dendrite problem. [8][9][10][11][12][13][14][15] As an important member in the transition metal oxide family, transition metal vanadate has attracted much attention due to the multivalent properties of vanadium, which could deliver considerable capacity based on the multielectron transfer. [16,17] Additionally, the vanadium oxide presents strong VO bond during electrochemical process, suggesting the smaller volume change compared with traditional conversion-type electrodes. [18] For LIBs application, it is reported that the vanadium oxide can store lithium ions on the basis of the intercalation reaction mechanism, and provide the reaction sites for the conversion reaction between transition metal and metal oxide, preventing the aggregation of the obtained highly active metal nanograins, improving the cycling performance of the active material. [19,20] Furthermore, the binary metal oxide could exhibit higher electrochemical activity compared to the single metal oxide electrode. [21] Calcium vanadate nanowires have been synthesized as a novel sodium-ion anode material, which delivered a superior cycling performance (1600 cycles), excellent rate performance (5000 mA g −1 ), and an applicable reversible capacity (>300 mA h g −1 ). [16] Lou's group has developed triple-shelled Preventing the aggregation of nanosized electrode materials is a key point to fully utilize the advantage of the high capacity. In this work, a facile and lowcost surface solvation treatment is developed to synthesize Fe 2 VO 4 hierarchical porous microparticles, which efficiently prevents the aggregation of the Fe 2 VO 4 primary nanoparticles. The reaction between alcohol molecules and surface hydroxy groups is confirmed by density functional theory calculations and Fourier transform infrared spectroscopy. The electrochemical mechanism of Fe 2 VO 4 as lithium-ion battery anode is characterized by in situ X-ray diffraction for the first time. This electrode material is capable of delivering a high reversible discharge capacity of 799 mA h g −1 ...