The Preparation And Electrochemical Performance Of Porous Silica-based Cathode Materials For Aqueous Zinc-ion Batteries

With the rapid development of economy,the problem of energy and environmental pollution is becoming more and more serious.Therefore,the development of environment-friendly,green and efficient new energy technology has become the leading direction of the global energy revolution.Aqueous zinc-ion batteries（AZIBs）are attracting attention due to their advantages of high safety,low cost and environmental friendliness.Therein,manganese oxide has become one of the most potential anode materials for AZIBs due to its abundant reserves,low cost,low toxicity and high theoretical charge-discharge capacity.Thus,the preparation and electrochemical performance of AZIBs cathode materials with high capacity,high stability and low polarization were studied in this paper.The specific research contents are as follows:（1）Preparation and characterization of porous silicon（P-Si）.In this work,white carbon black was applied as precursor of P-Si,and LiAlH₄was applied to reduce white carbon black at low temperature.Subsequently,the element composition,crystal structure and hydrophilicity of P-Si were investigated by various characterization methods.（2）P-Si was applied as support to prepare MnO_x@P-Si composite material,and its electrochemical performance was investigated.The results showed that MnO_x@P-Si exhibited the best electrochemical performance when the mass ratio of P-Si to MnO_x was 1:4.At 0.1A g^-1,the specific discharge capacity was about 242.6 mAh g^-1,and it still maintained 149.7 mAh g^-1 after 400 cycles;the retention rate was 61.7%,and the capacity decay rate was about 0.096%.Those results indicated that MnO_x@P-Si cathode materials had high feasibility in AZIBs application.At the same time,the hydrophobic property of P-Si offset the redox reaction of H₂O in the voltage window of 0～2 V,which could increase the operating voltage.These findings would further promote the development of manganese oxide composites for low cost and high electrochemical performance in the applications of AZIBs.（3）Preparation of vitamin B₁₂/manganese oxide/P-Si（Co-MnO_x/P-Si）composite materials and studying on its electrochemical performance as AZIBs cathode material.In order to further improve the electrochemical performance of AZIBs cathode material,Co-MnO_x/P-Si cathode material was successfully prepared using vitamin B₁₂ as raw material.Using Co-MnO_x/P-Si composite material as the AZIBs cathode material,the working electrode and button battery were successfully prepared and their electrochemical performance was investigated.The experimental results presented that the Co-MnO_x/P-Si cathode material with a large amount of oxygen vacancy,which could effectively enhance the charge-discharge performance.When the mass ratio of vitamin B₁₂,MnO_xand P-Si was0.09:4:1,Co-MnO_x/P-Si showed the best electrochemical performance.The discharge specific capacity of Co-MnO_x/P-Si was 710.4 mAh g^-1,and the discharge specific capacity still remained at 405.2 mAh g^-1 after 400cycles.The discharge specific capacity retention rate was 57.3%,and the discharge specific capacity decay rate was about 0.1%per cycle.At the same time,the coulomb efficiency was maintained at about 100%.All the above results indicated that Co-MnO_x/P-Si cathode material showed certain application potential in AZIBs.