Preparation And Zinc Storage Performance Of Ion Pre-intercalated Manganese Oxide-based Materials

Aqueous zinc ion batteries（ZIBs）are considered a promising alternative to LIBs due to their low cost and high safety.Among the cathode materials of ZIBs,slow kinetics,structural damage,and the dissolution of Mn²⁺severely limit the actual electrochemical performance of manganese-based cathode materials.Therefore,in this paper,the ion-intercalated manganese oxide-based materials are designed and prepared,and the influence of the composition of the materials on their phase,morphology and electrochemical performance is explored.Specifically include the following:Sn_xMn O₂/Sn O₂ with different Sn contents are prepared by the hydrothermal method.When the optimal molar ratio of Mn to Sn is 6:1,the material exhibits a high discharge capacity of 316.1 m Ah g^-1 at 0.3 A g^-1 and a high discharge capacity of 179.6m Ah g^-1 at 2.0 A g^-1,and the capacity retention rate is 92.4%after 2000 cycles.The excellent electrochemical performance can be attributed to the dual effect of Sn_xMn O₂/Sn O₂ heterostructure and the pre-intercalation of Sn⁴⁺.Specifically,the enough hetero-interface between the Sn_xMn O₂/Sn O₂ heterostructure and the expanded interlayer spacing caused by the pre-intercalation of Sn⁴⁺accelerate the ion/electron transfer and ensure the fast kinetic process.The“structural pillars”of Sn⁴⁺and the“pinning effect”of inert Sn O₂ prevent the structural collapse and ensure the long-term cycle stability.The NH₄⁺with a smaller molar mass is pre-intercalated into Mn O₂ to prepare（NH₄）_xMn O₂ material.The influence of NH₄⁺content on phase,morphology and electrochemical performance is analyzed.The material delivers a high discharge capacity of 228.7 m Ah g^-1 at 0.3 A g^-1 and a high discharge capacity of 122.5 m Ah g^-1at 3.0 A g^-1.The battery has no obvious capacity fading after 1500 cycles at 2.0 A g^-1.On the one hand,the pre-intercalation of NH₄⁺with a smaller molar mass increases the interlayer spacing of Mn O₂ and accelerates the ion transport kinetics.On the other hand,the“structural pillars”of NH₄⁺and the hydrogen bond formed between NH₄⁺and the main body of Mn O₂ greatly stabilize the layered structure and ensure the cycle stability of the（NH₄）_xMn O₂ material.