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Cobalt diselenide (CoSe2) has drawn great concern as an anode material for sodium-ion batteries due to its considerable theoretical capacity. Nevertheless, the poor cycling stability and rate performance still impede its practical implantation. Here, CoSe2/nitrogen-doped carbon-skeleton hybrid microcubes with a TiO2 layer (denoted as TNC-CoSe2) are favorably prepared via a facile template-engaged strategy, in which a TiO2-coated Prussian blue analogue of Co3[Co­(CN)6]2 is used as a new precursor accompanied with a selenization procedure. Such structures can concurrently boost ion and electron diffusion kinetics and inhibit the structural degradation during cycling through the close contact between the TiO2 layer and NC-CoSe2. Besides, this hybrid structure promotes the superior Na-ion intercalation pseudocapacitance due to the well-designed interfaces. The as-prepared TNC-CoSe2 microcubes exhibit a superior cycling capability (511 mA h g–1 at 0.2 A g–1 after 200 cycles) and long cycling life (456 mA h g–1 at 6.4 A g–1 for 6000 cycles with a retention of 92.7%). Coupled with a sodium vanadium fluorophosphate (Na3V2(PO4)2F3)@C cathode, this assembled full cell displays a specific capacity of 281 mA h g–1 at 0.2 A g–1 for 100 cycles. This work can be potentially used to improve other metal selenide-based anodes for rechargeable batteries.

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Na3V2(PO4)2F3 (NVPF) is a suitable cathode for sodium‐ion batteries owing to its stable structure. However, the large radius of Na+ restricts diffusion kinetics during charging and discharging. Thus, in this study, a phosphomolybdic acid (PMA)‐assisted hydrothermal method is proposed. In the hydrothermal process, the NVPF morphologies vary from bulk to cuboid with varying PMA contents. The optimal channel for accelerated Na+ transmission is obtained by cuboid NVPF. With nitrogen‐doping of carbon, the conductivity of NVPF is further enhanced. Combined with crystal growth engineering and surface modification, the optimal nitrogen‐doped carbon‐covered NVPF cuboid (c‐NVPF@NC) exhibits a high initial discharge capacity of 121 mAh g−1 at 0.2 C. Coupled with a commercial hard carbon (CHC) anode, the c‐NVPF@NC||CHC full battery delivers 118 mAh g−1 at 0.2 C, thereby achieving a high energy density of 450 Wh kg−1. Therefore, this work provides a novel strategy for boosting electrochemical performance by crystal growth engineering and surface modification.