Transition metal assisted synthesis of tunable pore structure carbon with high performance as sodium/lithium ion battery anode

Template method has been used as an important method to prepare porous materials. However, there are few reports about template method employing potassium chloride as template. Here, potassium chloride is employed as a template to prepare the porous carbon, and transition metal nitrates (Fe(NO₃)₂,d Co(NO₃)₂, Ni(NO₃)₂) are introduced to catalyze graphitization and to result different carbon structure during carbonization (denoted as Fe@C, Co@C and Ni@C). The Fe@C shows a formicary-like structure with an about 20 nm pore diameter and the Co@C displays a completely compact structure. Whereas, the Ni@C exhibits a foam-like structure with hierarchical porous structure consisting of macroporous frameworks, mesopores and ultrathin porous walls (∼5 nm). Its macropore and mesopore diameter is around 100 nm and 4 nm, respectively, its specific surface area is 464.5 m² g⁻¹. When adopted as anode material, the Ni@C presents much outstanding rate and cycling capability for lithium and sodium storage than Fe@C and Co@C, the capacity for sodium storage is 260 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹ and 92 mAh g⁻¹ after 1000 cycles at 1A g⁻¹, and the capacity for lithium storage is 683 mAh g⁻¹ after 1000 cycles at a current density of 1 A g⁻¹.