  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.
