In-situ preparation of multi-layered sandwich-like CuCo₂S₄/rGO architectures as anode material for high-performance lithium and sodium ion batteries

To improve electron transfer and ion diffusion for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), multi-layered sandwich-like CuCo₂S₄/rGO architectures (MS-CuCo₂S₄/rGO) are fabricated, in which the inserted CuCo₂S₄ spheres are anchored on the surface of rGO tightly due to strong chemical bonding. The MS-CuCo₂S₄/rGO architectures exhibit impressive electrochemical performance as anodes for both LIBs and SIBs. They show a high and stable capacities of 792 mAh g⁻¹ at 500 mA g⁻¹ after 1000 cycles for LIBs and 344.5 mAh g⁻¹ at 1000 mA g⁻¹ after 800 cycles for SIBs, which are 5 and 3.5 times that of pure CuCo₂S₄ for LIBs and SIBs, respectively. The electrochemical results show about 77.8% and 68.4% charge contribution from capacitive-controlled capacity for LIBs and SIBs, leading to excellent electrochemical performance. The in-situ XRD tests also prove that a conversion-type sodium storage mechanism is beneficial to high capacity. Additionally, the successfully paired Na₃V₂(PO₄)₃||MS-CuCo₂S₄/rGO full sodium ion cell displays a reversible capacity of 225 mAh g⁻¹ at 500 mA g⁻¹ after 100 cycles. These results will shed light on the practical application of MS-CuCo₂S₄/rGO as high-performance electrode with long-term cycling stability for next generation LIBs and SIBs.