CuFeS2 anchored in ethylenediamine-modified reduced graphene oxide as an anode material for sodium ion batteries

• CuFeS 2 /EN-rGO as sodium-ion battery anode material was researched. • Sodium storage mechanism of CuFeS 2 was explored systematically. • The CuFeS 2 /EN-rGO anode shows a high capacity and good cycle stability. Tetragonal CuFeS 2 anchored in ethylenediamine-modified reduced graphene oxide ( CuFeS 2 /EN-rGO) was synthesized via a simple solvothermal method, and evaluated for the first time as an anode material for sodium ion batteries via constant current charge/discharge, rate charge/discharge, cyclic voltammetry, electrochemical impedance spectroscopy. Ex-situ XRD revealed sodium storage mechanism of CuFeS 2 , indicating that its capacity is mainly provided by the conversion reaction. Compared with CuFeS 2 , reversible capacity and cycle performance of CuFeS 2 /EN-rGO was significantly improved by high electrical conductivity of EN-rGO. At 1.0 A g −1 , the discharge capacity of CuFeS 2 /EN-rGO maintained 247.8 mAh g −1 at 250th cycle, corresponding to 0.14% discharge capacity decay rate per cycle compared with its second discharge capacity. Even at 3.2 A g −1 , it can reached a discharge capacity of 296.2 mAh g −1 . The results show that CuFeS 2 /EN-rGO has certain development prospects as an anode material for sodium ion batteries.