Multifunctional interlayer provides a robust interfacial tunnel environment for highly reversible zinc-ion batteries

Intercalation chemistry/engineering has attracted much attention in the development of electrochemical energy storage. This study employs a green synthesis method to insert cetyltrimethylammonium bromide (CTAB) into Cu_2-xSe at room temperature, thereby producing a Cu_2-xSe doped material with an expanded interlayer spacing and a nanoplate array structure. Reversible insertion/extraction of Zn²⁺ in Cu_2-xSe-CTAB is facilitated through an intercalation reaction mechanism, as evidenced by ex situ X-ray diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy measurements (XPS). Moreover, the CTAB adsorbed on the surface of the zinc anode can regulate the deposition of Zn²⁺ and inhibit the formation of dendrites. Benefiting from the above advantages, Cu_2-xSe-CTAB shows a high specific capacity of 661.4 mAh·g⁻¹ at 0.1 A·g⁻¹ as an electrode material for zinc ion batteries, delivered an extraordinary rate capability of 230.2 mAh·g⁻¹ at 3 A·g⁻¹ and excellent cycling stability. Theoretical calculations further demonstrate that the incorporation of CTAB diminishes the electrostatic repulsion between zinc ions and the matrix, facilitating rapid diffusion kinetics of zinc ions, and effectively mitigating the dissolution and volume expansion of the cathode. In addition, a Zn||Cu_2-xSe-CTAB pouch cell has been assembled, delivering a high capacity of 176 mAh·g⁻¹ at 1.0 A·g⁻¹ after 600 cycles and exhibiting a superior long cycling stability. This work highlights the potential of CTAB as a promising solution, providing new opportunities for the development of high-performance rechargeable ZIBs.