SnO2/Bi2O3/NF heterojunction with ordered macro/meso-pore structure as an advanced binder-free anode for lithium ion batteries

Abstract

So far, the high theoretical specific capacity metal oxide is considered as a promising anode material for lithium-ion batteries (LIBs). Unfortunately, the intrinsic poor conductivity and structural stability of metal oxide, the huge volume expansion during the cycling cause serious capacity fading and unstable cycle. Here, the three-dimensional (3D) ordered inverse opal (IO) heterojunction structure of SnO2/Bi2O3 on commercial nickel foam (NF) were fabricated. When used as a binder-free anode material for LIBs, the initial discharge specific capacity and charge specific capacity of the IOs electrode were 1229 mA h g−1 and 1098 mA h g−1. The SnO2/Bi2O3/NF IOs exhibited excellent electrochemical activity and delivered a discharge capacity about 493 mA h g−1 after 500 cycles at the current density of 1000 mA g−1, the Coulomb efficiency (CE) had been maintained at around 100%, which was much more than the control groups of SnO2/NF IOs (247 mA h g−1) and Bi2O3/NF IOs (124 mA h g−1). Furthermore, the prepared was successfully assembled with commercial LiFePO4 to a full cell that displayed stable capacity about 101.2 mA h g−1 at the current density of 100 mA g−1 after 100 cycles. The excellent performance of SnO2/Bi2O3/NF IOs is due to that the 3D interconnected macroporous and mesoporous structures can shorten the transmission path of ions/electrons and buffer volume expansion. In addition, the heterojunction structure with obvious lattice defects can effectively promote the contact between electrode material and electrolyte. The strategy in this study lights on the illuminating design of 3D inverse opal heterostructure binder-free anode, and the obtained product has a great potential as the anode material applied in next-generation LIBs.