In-situ co-construction of carbon coating layer and SWCNTs conductive network for high-capacity nickel-iron oxide anodes

Abstract

In recent years, the market has pushed for higher energy density requirements for secondary rechargeable batteries. Bimetallic oxides are promising candidates for replacing graphite anode materials in lithium-ion batteries with high energy density. To improve the electrochemical performance of NiFe2O4 nanoparticles, a carbon coating layer and single-walled carbon nanotubes (SWCNTs) conductive network were in situ co-constructed simultaneously using a solvothermal method, taking into account the poor inherent conductivity and volume change upon cycling of bimetallic oxides. The cycle stability and rate capability of the obtained NiFe2O4 @C/CNTs composites with varying CNTs amounts were investigated. After 100 cycles at a current density of 200 mA g−1, the reversible capacity of NiFe2O4 @C/CNTs is 1111.8 mAh g−1. The specific capacity can still reach 631.6 mAh g−1, even at 800 mA g−1. NiFe2O4 @C/CNTs exhibits significantly improved cycle stability and rate capability in addition to high capacity. The remarkable electrochemical performance is due to the surface protective effect of the carbon coating layer as well as the conductive effect of the SWCNTs network. By firmly attaching the NiFe2O4 active nanoparticles to the electrode, unhindered electron transport and rapid diffusion of lithium ions can be realized, and volume change during cycling can be inhibited. This research paves the way for the general modification of electrode materials with low conductivity.