Tailoring the Na storage performance of mixed-phase zinc tin oxide anode by additive-controlled synthesis

Combining two electrochemically active elements into anode materials has emerged as a promising strategy for practical application in the next-generation sodium-ion batteries (SIBs). Herein, a mixed-phase coexistence of ZnSnO3 and Zn2SnO4 is successfully modulated by controlling the amount of cetyltrimethylammonium bromide (CTAB) via additive-assisted hydrothermal synthesis. The structural characterizations exhibit that the higher the concentration of CTAB added to the precursor solution, the higher the phase fraction of ZnSnO3. The effect of incorporating CTAB additive on the interfacial synergy between the ZnSnO3 and Zn2SnO4 phases is also revealed by x-ray photoelectron spectroscopy. When using the mixed-phase materials as an anode in SIBs, the optimal addition of CTAB (ZTO500) demonstrates an excellent specific discharge capacity of ∼277.7 mAh g−1 with an 88 % retention after cycling 100 times at 50 mA g−1. Electrochemical characterizations show that by modulating the mixed-phase of ZnSnO3 and Zn2SnO4, a superior charge transfer and conductivity across the anode are obtained, which also causes the combination of diffusion- and surface capacitive-controlled charge storage. Modulated mixed-phase engineering would provide a promising approach for effectively designing proper anodes in SIBs. [Display omitted] •A mixed-phase ZTO anode was designed by an additive-assisted hydrothermal route.•By controlling the amount of CTAB, the mixed-phase of ZnSnO3 and Zn2SnO4 was modulated.•The optimal anode showed a good capacity of 277.7 mAh g−1 and 88 % retention after cycling.•The optimal mixed-phase modifies the charge transfer and Na-ion diffusion kinetics.