Effect of calcination temperature on the electrochemical performance of nickel nanoparticles on carbon coated porous silicon nanospheres anode for lithium-ion batteries

Si/C composite has been widely studied as high performance anode for lithium-ion batteries (LIBs) due to its high capacity and abundant resource. However, its practical application is still hampered by the limited electronic conductivity. Herein, Ni nanoparticles are introduced on Si/C composite by calcining porous Si covered with Ni²⁺-polydopamine complexes in this paper. The effect of the calcination temperature on the structure and electrochemical property of the obtained Si@C-Ni composite anode is systematically studied. When the calcination temperature is 550 °C, the Si@C-Ni shows the best electrochemical performance (a high capacity of 1622.9 mA h g⁻¹ at 0.2 A g⁻¹ after 100 cycles and an excellent rate performance of 1140 mA h g⁻¹ at 6.4 A g⁻¹). Its outstanding electrochemical performance of Si@C-Ni-550 is related to the optimized size and uniform dispersion of Ni nanoparticles which can offer additional electron highway, boosting the electronic conductivity of Si/C composite. Higher calcination temperature (≥650 °C) leads to the rapid increase of Ni nanoparticles size which results in Ni aggregation on carbon, reducing the cycling stability and rate capability of Si@C-Ni. Our work offers a guide to prepare high performance metal-rich Si/C composite anode with appropriate synthetic temperature for LIBs.