Aqueous zinc-ion batteries (AZIBs) are promising contenders for energy storage systems owing to their low cost and high safety. However, their practical application is hindered by uncontrolled Zn dendrites and other side reactions. Here, the three-dimensional (3D) TiO₂/Cu₂Se/C heterostructure layer derived from MXene/Cu-MOF is constructed on the Zn anode to control the deposition/dissolution behavior, which has numerous active sites, better electrical conductivity and excellent structural stability. Based on DFT calculation, the built-in electric field (BIEF) formed of TiO₂/Cu₂Se/C can enhance charge transfer and ionic diffusion to inhibit the dendrites. Furthermore, hydrophobic coating has the ability to impede the corrosion and hydrogen evolution reaction (HER) of zinc anode. Thus, TiO₂/Cu₂Se/C@Zn enable the stable and reversible Zn plating/stripping process with the outstanding lifetime of 1100 h at 2 mA·cm^–2 and even 650 h at 10 mA·cm^–2. The batteries constructed with commercial MnO₂ cathodes demonstrate the remarkable capacity (248.7 mAh·g⁻¹ at 0.1 A·g⁻¹) and impressive cycle stability (with 71.3% capacity retention after 300 cycles). As well as extending the life of AZIBs, this study is also motivating for other metal anode based secondary batteries.

Mn-based zinc ion battery has the advantages of low cost and high performance, which makes it the promising energy storage system. However, the poor conductivity and the agglomeration in the synthesis process of manganese-based materials restrict the performance of batteries. Herein, the Se-doped MnS/Ti₃C₂T_x (Se-MnS/Ti₃C₂T_x) composite material derived from Mn-based metal-organic framework is reported. Electrochemical tests show that Se-doped could generate S defects and enhance the electrochemical activity of MnS. At the same time, the introduction of Ti₃C₂T_x substrate is conducive to exposing more sulfur defects and improving the utilization rate of defects. In the mechanism study, it is found that Se-MnS/Ti₃C₂T_x is transformed into S/Se co-doped Mn₃O₄ at the first charge, which innovatively elucidated the behavior of S/Se during activation. In the electrochemical performance test, the specific capacity can reach 74.7 mAh·g⁻¹ at 5.0 A·g⁻¹. In addition, the Zn-Ti₃C₂T_x membrane electrode is prepared by vacuum filtration as the zinc-poor anode, which is assembled into the rocking chair full battery to avoid dendrite growth and exhibit excellent rate performance. The addition of Zn²⁺ weakens the electrostatic repulsion between the interlayers of MXene, and the formation of the folded morphology aids the penetration of the electrolyte. At 1.0 A·g⁻¹, the capacity can reach 50.6 mAh·g⁻¹. This work is helpful to promote the research and development of the reaction mechanism of manganese based rocking chair batteries.

It is of vital importance to design efficient and low-cost bifunctional catalysts for the electrochemical water splitting under alkaline and neutral pH conditions. In this work, we report an efficient and stable NiCo₂S₄/N, S co-doped reduced graphene oxide (NCS/NS-rGO) electrocatalyst for water splitting, in which NCS microspheres are composed of one-dimentional (1D) nanorods grown homogeneously on the surface of NS-rGOs). The synergetic effect, abundant active sites, and hybridization of NCS/NS-rGO endow their outstanding electrocatalytic performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both alkaline and neutral conditions. Furthermore, NCS/NS-rGO employed as both anode and cathode in a two-electrode alkaline and neutral system electrolyzers deliver 10 mA/cm² with the low cell voltage of 1.58 V in alkaline and 1.91 V in neutral condition. These results illustrate the rational design of carbon-supported nickel-cobalt based bifunctional materials for practical water splitting over a wide pH range.