花状纳米Bi₂MoO₆/EG复合材料构建高性能非对称超级电容器

Construction of High-Performance Asymmetric Supercapacitors with Nanoflower Bi₂MoO₆/EG Composites

摘要: 本文针对超级电容器赝电容材料导电性差的问题，通过溶剂热法将Bi₂MoO₆纳米花负载于膨胀石墨(EG)表面，成功制备了Bi₂MoO₆/EG复合负极材料。EG的引入显著提升了材料的导电性，电化学测试表明，Bi₂MoO₆/EG在2 A·g⁻¹电流密度下比电容达886.7 F·g⁻¹，30 A·g⁻¹时仍保持427.5 F·g⁻¹ (倍率性能48%)，且循环2500次后电容保持率为90.5%。同时，以Ni-MOF为前驱体合成了NiO/C正极材料，其比电容为683.5 F·g⁻¹，25 A·g⁻¹下倍率性能达76.9%，循环稳定性优异(2500次后保持95.5%)。基于上述材料构建的Bi₂MoO₆/EG//NiO/C非对称超级电容器(ASC)在1.8 V工作电压下，最大能量密度为45.05 Wh·kg⁻¹ (功率密度1800 W·kg⁻¹)，7000次循环后电容保持率91.2%。研究结果表明，Bi₂MoO₆/EG复合材料通过EG的导电网络与赝电容协同效应显著提升了储能性能，为非对称超级电容器的实际应用提供了新思路。

Abstract: To address the issue of poor conductivity of pseudocapacitive materials in supercapacitors, Bi₂MoO₆ nanoflowers were loaded onto expanded graphite (EG) using a solvothermal method. The incorporation of EG markedly improved the material’s electrical conductivity. Electrochemical tests revealed that the Bi₂MoO₆/EG composite attained a specific capacitance of 886.7 F·g⁻¹ at 2 A·g⁻¹ and maintained 427.5 F·g⁻¹ at 30 A·g⁻¹ (rate performance of 48%), with a capacitance retention of 90.5% following 2500 cycles. Furthermore, the NiO/C cathode material, obtained from Ni-MOF precursors, had a specific capacitance of 683.5 F·g⁻¹ and a rate capability of 76.9% at 25 A·g⁻¹, in addition to remarkable cycling stability with 95.5% retention after 2500 cycles. The fabricated Bi₂MoO₆/EG//NiO/C asymmetric supercapacitor (ASC) functioned at 1.8 V, achieving a peak energy density of 45.05 Wh·kg⁻¹ (power density: 1800 W·kg⁻¹) and maintained 91.2% of its original capacitance after 7000 cycles. The results show that the Bi₂MoO₆/EG composite material improves energy storage performance significantly through the synergistic effect of EG’s conductive network and pseudocapacitance, providing new ideas for asymmetric supercapacitors.