Preparation of rGO/Sn/Na2Sn(PO4)2 as high performance anode material for lithium ion batteries

Abstract Layered Sn(HPO 4 ) 2 is a potential anode material for lithium ion batteries, but it has the low initial Coulombic efficiency and poor electrical conductivity. To overcome these disadvantages, Sn/Na 2 Sn(PO 4 ) 2 was synthesized by a one-step ion exchange and chemical deposition, then coated by rGO to form rGO/Sn/Na 2 Sn(PO 4 ) 2 composite. In the composite, rGO constructs a three-dimensional conductive network structure, and protons in Sn(HPO 4 ) 2 are replaced by Na + to form Na 2 Sn(PO 4 ) 2 and Sn nanoparticles are evenly distributed on Na 2 Sn(PO 4 ) 2 surface. The rGO/Sn/Na 2 Sn(PO 4 ) 2 as anode for lithium ion batteries not only exhibits decent initial Coulombic efficiency of 60.17%, but also excellent rate capability with specific capacities of 461.9, 361.4, and 289.1 mA h g −1 at current densities of 2, 5, and 10 A g −1 , respectively. Moreover, compared to Sn(HPO 4 ) 2 and Sn/Na 2 Sn(PO 4 ) 2 , rGO/Sn/Na 2 Sn(PO 4 ) 2 delivers the superior cyclic stability with specific capacity of 670.7 mA h g −1 after 120 charge/discharge cycles and electrochemical kinetic property with R ct of 62.1 Ω, which can be attributed to the three-dimensional network structure formed by rGO.