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Recently, as a new breakthrough for lithium-ion storage anode materials, transition metal vanadates, such as Fe 2 VO 4 , have attracted much attention, which, however, still suffer from slow electrochemical kinetics and substantial volume expansion. Hybrid with high conductivity materials is an effective route to deal with these issues. Herein, in situ synthesis of Fe 2 VO 4 @Ti 3 C 2 T x composites with porous sandwich structure by co-precipitation-calcination process was reported. Ultrafine Fe 2 VO 4 nanoparticles (10–15 nm) in situ grew and was anchored on Ti 3 C 2 T x nanosheets, which effectively inhibits both the grain growth for Fe 2 VO 4 and stacking for Ti 3 C 2 T x , thus facilitating the electrochemical kinetics and alleviating the volume change of Fe 2 VO 4 to maintain the integrated structure during the cycling process. As a result, Fe 2 VO 4 @Ti 3 C 2 T x anode shows high Li+ diffusion coefficient (2.72 × 10−11 cm2 s−1) and pseudocapacitive charge storage mechanism (capacitive charge storage contribution 70.85–84.80 % at 0.2–1.0 mV s−1), which guarantee rapid charging and discharging capability. Consequently, outstanding rate performance (1012–595 mAh g−1 at 0.2–3.0 A g−1) and superior cycling capability (663 and 416 mAh g−1 at 1.0 A g−1 for 200 cycles and 2.0 A g−1 for 500 cycles, with the average capacity attrition rate of 0.059 % and 0.053 %, respectively), were achieved, which render Fe 2 VO 4 @Ti 3 C 2 T x composites important potential for lithium-ion storage. • 10–15 nm Fe 2 VO 4 nanoparticles in situ grew and anchored on Ti 3 C 2 T x nanosheets, with a high surface area of 80.32 m2 g–1. • Grain growth of Fe 2 VO 4 nanoparticles and stacking of Ti 3 C 2 T x nanosheets were inhibited by the synergy effect. • Unique structure optimized the electrochemical kinetics and the volume change of Fe 2 VO 4 during cycling process. • High Li+ diffusion (2.72 × 10–11 cm2 s–1) and pseudocapacitive mechanism led to a rapid cycling capability. • Superior Li ion storage (416 mAh g–1 at 2 A g–1 for 500 cycles, 0.053 % average capacity decay) was achieved. [ABSTRACT FROM AUTHOR]

• The Sn(OH) 4 are first employed as the anode materials for LIBs, showing higher capacity and longer cycle life. • Mesocarbon microbeads (MCMB) via air-oxidation treatment are acted as the carrier to anchor the ultra-small size Sn(OH) 4. • The discharge mechanisms of Sn(OH) 4 is first proposed according to the CV curves, TEM and XRD characterizations. • The LiOH and carbon can shorten the lithium ion diffusion pathway and buffer the volume expansion and aggregation of Sn. • This composite presents excellent cycling stability and large reversible capacity as an electrode material. SnO 2 -based composites have attracted considerable attention as anode for lithium-ion batteries due to their high theoretical capacity and cost-effectiveness. However, capacity fading often occurs due to the severe volume expansion and cracking during cycling. Herein, ultra-small Sn(OH) 4 nanoparticles have been deposited on the surface of mesocarbon microbeads (MCMB) via a low-temperature air-oxidation treatment. The in-situ oxygenated functional groups from beta-resin on the surface of MCMB lead to the high loading of Sn(OH) 4 nanoparticles with the sizes of 2–3 nm. Interestingly, compared to SnO 2 , the as-prepared Sn(OH) 4 nanoparticles in the composite exhibits a higher reversible specific capacity of 850 mA h g−1 after 50 cycles at a current density of 100 mA g−1. This is because the small sizes of Sn(OH) 4 NPs buffer the large volume expansion and remain stable structure during cycling. The electrochemical reaction mechanism of Sn(OH) 4 is further clarified, in which the generated LiOH can effectively prevent the Sn agglomeration. LiOH also enables the composite to show low diffusion impedance and better electrochemical performance. Therefore, novel Sn(OH) 4 /MCMB composite provides the possibility for practical energy storage devices. [ABSTRACT FROM AUTHOR]