Carbon-coated Ni3Sn2 nanoparticles embedded in porous carbon nanosheets as a lithium ion battery anode with outstanding cycling stability

Abstract

Carbon-coated Ni₃Sn₂ nanoparticles uniformly embedded in two-dimensional porous carbon nanosheets (2D Ni₃Sn₂@C@PGC) as superior lithium ion battery anode material were fabricated by a facile and scalable method, which involves in situ synthesis of 2D Ni@C@PGC and chemical vapor transformation processes from 2D Ni@C@PGC to Ni₃Sn₂@C@PGC. With the assistance of a water-soluble cubic NaCl template, 2D Ni@C@PGC was firstly in situ synthesized on the surface of NaCl particles. After vapor transformation with SnCl₂, the Ni@C@PGC nanosheets were converted to Ni₃Sn₂@C@PGC, in which uniform Ni₃Sn₂ nanoparticles coated with conformal graphitized carbon layers were homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of about 30 nm. This unique 2D dual encapsulation structure with high porosity, high electronic conductivity, outstanding mechanical flexibility and short lithium ion diffusion pathway is favorable for lithium insertion and extraction during deep charge–discharge processes. As a result, the electrode fabricated using 2D Ni₃Sn₂@C@PGC as the anode and a lithium plate as the cathode exhibits a high reversible capacity up to 585.3 mA h g⁻¹ at a current density of 0.2 C (1 C = 570 mA h g⁻¹) after 100 cycles, a high rate capability (484, 424, 378, 314 and 188 mA h g⁻¹ at 0.2, 0.5, 1, 2 and 5 C, respectively, 1 C = 570 mA h g⁻¹), and superior cycling stability at a high rate (350.3 mA h g⁻¹ at a rate of 1 C after 180 cycles).