1成果简介

 　　NiCo₂O₄纳米结构已成为高性能超级电容器电极的理想候选材料。本文，上海电力大学徐燕、朱燕艳 教授等在《ACS Appl. Nano Mater》期刊发表名为“Three Dimensional Graphene Aerogel Encapsulated NiCo2O4 Sea Urchin-like Nanospheres for Supercapacitor Application”的论文，研究提出采用水热法合成NiCo₂O₄纳米结构，并通过整合三维石墨烯（3DG）网络进一步增强其电化学性能。该3DG涂层有效防止了NiCo₂O₄纳米粒子的团聚，形成了分级多孔通道，并在纳米尺度上显著扩展了活性表面积。
　　优化后的3DG/NiCo₂O₄纳米复合材料展现出卓越的电荷存储能力，在1 A/g电流密度下实现高达700.73 F/g的比电容，并具备优异的循环稳定性——经5000次循环后电容保持率达96.24%。当配置为非对称超级电容器（3DG/NiCo2O4//AC）用于储能应用时，该器件在功率密度749.81 W/kg下实现16.35 Wh/kg的卓越能量密度，并在6000次循环后保持85.63%的容量保持率。这些成果凸显了纳米尺度结构工程在开发先进储能材料中的关键作用。
　　2图文导读

  
　　图1. Step-by-step schematic of the 3DG/NiCo2O4 preparation method.

　　图2. (a,b) SEM images revealing the surface morphology of pristine NiCo2O4; (c,d) SEM images demonstrating the three-dimensional graphene-supported NiCo2O4 (3DG/NiCo2O4); (e) TEM image showing the detailed nanostructure of 3DG/NiCo2O4; (f) HRTEM image displaying the crystallographic features; and (g–k) corresponding TEM-based elemental mapping images.

　　图3. (a) XRD patterns demonstrating the crystalline phases of NiCo2O4 and 3DG/NiCo2O4; (b) XPS survey spectra revealing the elemental composition, with high-resolution XPS spectra of 3DG/NiCo2O4 showing (c) C 1s, (d) O 1s, (e) Co 2p, and (f) Ni 2p core-level states; (g) Raman spectra highlighting the carbon structure of NiCo2O4 and 3DG/NiCo2O4; (h,i) N2 adsorption–desorption isotherms and corresponding pore size distribution curves from BET analysis.

　　图4. (a) CV curves of 3DG/NiCo2O4 at different scan rates; (b) CV curves of the NiCo2O4 and 3DG/NiCo2O4 electrodes at 50 mV/s; (c) GCD curves of 3DG/NiCo2O4 and (d) NiCo2O4 at different current densities; (e) GCD curves of the NiCo2O4 and 3DG/NiCo2O4 electrodes at 2 A/g; (f) comparison of the specific capacitance of NiCo2O4 and 3DG/NiCo2O4 at different current densities; (g) GCD curves of 3DG/NiCo2O4 with different ratios of NiCo2O4 and 3DG, and (h) comparison of specific capacitance at 1 A/g current density extracted from GCD curves.

　　图5. (a) Comparison of electrochemical impedance spectra of NiCo2O4 and 3DG/NiCo2O4 (the inset shows the equivalent circuit diagrams of NiCo2O4 and 3DG/NiCo2O4); (b) Coulomb efficiency and specific capacity for 5000 cycles of 3DG/NiCo2O4 at a 5 A/g current density (the inset depicts the charge/discharge profiles for the first 5 and the last 5 cycles). (c) Redox peak current calculated b-values for 3DG/NiCo2O4 at different sweep rates; (d) CV curves for 3DG/NiCo2O4 at a sweep rate of 100 mV/s, where the shaded area represents the capacitive contribution; (e) percentage of capacitive control and diffusion control at different sweep rates.

　　图6. (a) Graphical representation of the 3DG/NiCo2O4//AC ASC device; (b) CV curves of 3DG/NiCo2O4 and AC at 100 mV/s; (c) CV curves and (d) GCD curves of the ASC device at various voltages; (e) CV curves of ASC at different scan rates; (f) GCD curves of the ASC device at different current densities; (g) the specific capacitance at different current densities; (h) Coulomb efficiency and specific capacity for 6000 cycles of 3DG/NiCo2O4 at a current density of 5 A/g.
　　3小结 
　　综上所述，研究通过结合水热生长与三维石墨烯集成的高效合成策略，成功开发出高性能3DG/NiCo₂O₄纳米复合电极。三维石墨烯的集成有效抑制了NiCo₂O₄纳米粒子的团聚，并构建出高导电性与机械强韧性兼备的纳米尺度网络。这种定制化纳米结构提供了丰富的活性位点，促进了高效的电荷传输，从而实现了卓越的电化学性能。该复合材料展现出高达700.73 F/g的比电容及优异的循环稳定性（5000次循环后容量保持率达96.24%）。在全固态非对称超级电容器（3DG/NiCo₂O₄//AC）中的实际应用验证表明：该器件在5A/g条件下经6000次严苛充放电循环后仍保持85.63%初始电容，彰显其在柔性微型化储能器件领域的巨大应用潜力。
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