Ni-decorated Sn(HPO4)2 anchored on reduced graphene oxide boosting initial Coulombic efficiency and cyclic stability for lithium-ion batteries

Abstract

Layered Sn(HPO4)2 with perfect crystal structure and large interlayer spacing shows considerable lithium storage capacity worthy of study, but its intrinsic poor conductivity and low initial Coulombic efficiency (ICE) as anode material for lithium-ion batteries need to be enhanced. Herein, Sn(HPO4)2 is first decorated by Ni nanoparticles through electroless plating, then anchored on reduced graphene oxide (rGO). The well-conductive Ni nanoparticles distributed uniformly on the surface of Sn(HPO4)2 can help to inhibit the irreversible sites on the surface and reduce electrochemical kinetic impedance, thus the Ni/Sn(HPO4)2 anode exhibits improved ICE and capacity retention ratios, which are almost twice that of bare Sn(HPO4)2 anode. Meanwhile, the conductive network formed by rGO in rGO/Ni/Sn(HPO4)2 composite not only weakens the electrochemical reaction polarization, but also keeps the electrode structure stable and provides extra lithium storage sites, so rGO/Ni/Sn(HPO4)2 anode delivers higher ICE of 60.29%, superior cyclic stability of 79.7% capacity retention after 120 cycles with at 0.1 A g−1.