Confining ultrafine ZnSe nanoparticles in N,Se-codoped carbon matrix using a direct solid state reaction approach for boosting sodium storage performance

Abstract As a most promising low-cost substitute for the current lithium-ion batteries technology, sodium-ion batteries (SIBs) have aroused particular attentions over the past few years. However, the performance of SIBs is still far from our expectations due to the lack of suitable electrode materials with excellent electrical conductivity, high energy density, long-term cycling stability, and high-rate performance. Herein, ultrafine ZnSe nanoparticles homogeneously confined within N,Se-codoped carbon matrix were constructed via a facile solid state reaction route. By directly using zinc acetate dihydrate, o-vanillin and o-phenylenediamine as starting raw materials, a self-assembly solid state reaction occurred to give rise to a bis-Schiff base complex with zinc (II) at room temperature. After subsequent calcination in the presence of selenium powder at elevated temperature, simultaneous carbonization and selenization took place, resulting to the in-situ formation of ultrafine ZnSe nanoparticles (∼6.5 nm) encapsulated in N,Se-codoped carbon matrix (named as ZnSe⊂NSeC). The unique ZnSe⊂NSeC hybrid demonstrated an impressive sodium storage performance in terms of long-term cycling stability (282 mA h g−1 of charging capacity after 500 cycles at 0.1 A g−1) and excellent rate capability (198 mA h g−1 of charging capacity at 5 A g−1). More importantly, a superb stable charging capacity of 238 mA h g−1 still maintained even after 1200 cycles at 1.0 A g−1. Such strategy may also be used to explore other nanocomposites to boost their energy storage performance.