A leaf-like Co-Silicate/CNT hybrid film as free-standing anode for lithium and sodium storage

Electrode materials with high theoretical capacity and high conductivity are critical for high performance rechargeable batteries. Herein, a leaf-like cobalt silicate nanosheet/carbon nanotube (Co-Silicate/CNT) hybrid film is synthesized through a hydrothermal strategy. The Co-Silicate nanosheets provide large accessible surface area and abundant low-coordinated surface atoms with high reactivity. Meanwhile, the Co-Silicate nanosheets are strongly coupled with internally connected CNTs, which afford fast electron transfer and high mechanical stability. Moreover, the open pores can effectively reduce the ion migration distance and alleviate volume changes during charging and discharging cycle. When used as a binder-free anode for LIBs, the Co-Silicate CNT hybrid film exhibits a high initial charge capacity of 846.8 mA h g⁻¹, a good rate performance (1451.3 mAh g⁻¹ when reset to 0.1 A g⁻¹ after additional 80 cycles) and excellent cycle performance (331.72 mAh g⁻¹ after 1000 cycles at 10 A g⁻¹). As anode materials for sodium storage, it also shows a good rate performance and cycle performance (246.3 mAh g⁻¹ after 500 cycles at 1 A g⁻¹). Reaction mechanism analysis reveals that the good performance results from the optimized 3D “branch-leaf” structure and combined effect of capacitance and insertion mechanism. These results indicate that the Co-Silicate/CNT hybrid film has great potential in practical applications as LIB/SIB electrodes.