Co0.85Se particles encapsulated in the inner wall of nitrogen-doped carbon matrix nanotubes with rational interfacial bonds for high-performance lithium-ion batteries

Abstract

Cobalt selenides based on the conversion reaction have been widely applied in lithium-ion batteries (LIBs) due to their high conductivity and high specific capacity. However, effectively suppressing the fast capacity fade caused by the irreversible Se/Co dissolution and serious volume change during the cycling process is still a challenge. Herein, a facile and efficient self-generated sacrificial template method is used to prepare Co_0.85Se nanoparticles encapsulated in the inner wall of N-doped carbon matrix nanotubes (Co_0.85Se@NCMT). In this strategy, the formation of stable Co–N/C and Se–C as well as enhancing the mechanical strength between active materials and N-doped carbon matrix nanotubes can critically affect the performance through suppressing the dissolution of Se/Co, decreasing energy band, promoting the shuttling of the ions/e⁻ moving and mitigating the volume expansion during the charge–discharge process, which play a key role in improving the structure stability and electrochemical performance. Besides, Co_0.85Se nanoparticles encapsulated in the robust carbon matrix inner wall can ensure good electron transfer and prevent the aggregation of nanoparticles, leading to superior electrochemical reversibility. Finally, carbon matrix nanotubes can provide sufficient space to effectively accommodate the volume changes of encapsulated Co_0.85Se nanoparticles, thereby improving the cyclic stability. Based on the above advantages, as expected, the electrochemical investigations exhibited that the Co_0.85Se@NCMT anode performs a stable reversible capacity of 462.9 mA h g⁻¹ at a large current density of 5 A g⁻¹ and a remarkable capacity retention of 99.5% after 800 cycles, suggesting its promising potential for the anode of LIBs.