Highly conductive Co3Se4 embedded in N-doped 3D interconnected carbonaceous network for enhanced lithium and sodium storage

[Display omitted] •Co3Se4 particles were uniformly grown on 3D Nitrogen-doped carbon network.•Excellent electrochemical performance was demonstrated in LIBs and SIBs.•We found that selenium element was generated in situ during the reaction of LIBs.•Selenium element can promote battery performance. Traditional cobalt selenides as active materials in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) would suffer from drastic volume expansions and large stacking effects, leading to a low cycling stability. In this work, we utilized a facile template method for preparing Co3Se4@N-CN (CSNC) that encapsulated Co3Se4 nanoparticles into 3D interconnected nitrogen-doped carbon network (N-CN). Satisfactorily, it possesses excellent cycling stability with enhanced lithium and sodium energy storage capacity. As an anode material in LIBs, CSNC exhibited a prominent reversible discharge performance of 1313.5 mAh g−1 after 100 cycles at 0.1 A g−1 and 835.6 mAh g−1 after 500 cycles at 1.0 A g−1. Interestingly, according to the analysis from cyclic voltammetry, the in-situ generated Se might provide extra capacity that leaded to a rising trend of capacity. When utilized as an anode in SIBs, CSNC delivered an outstanding capacity of 448.7 mAh g−1 after 100 cycles at 0.1 A g−1 and could retain 328.9 mAh g−1 (77.2% of that of 0.1 A g−1) even at a high current density of 5.0 A g−1. The results demonstrate that CSNC is a superior anode material in LIBs and SIBs with great promise. More importantly, this strategy opens up an effective avenue for the design of transition metal selenide/carbonaceous composites for advanced battery storage systems.