Klankowski Steven A, Pandey Gaind P, Malek Gary, Thomas Conor R, Bernasek Steven L, Wu Judy, Li Jun
Department of Chemistry, Kansas State University, Manhattan, KS 66506, USA.
Nanoscale. 2015 May 14;7(18):8485-94. doi: 10.1039/c5nr01198a.
A study on the development of high-power supercapacitor materials based on formation of thick mesoporous MnO2 shells on a highly conductive 3D template using vertically aligned carbon nanofibers (VACNFs). Coaxial manganese shells of 100 to 600 nm nominal thicknesses are sputter-coated on VACNFs and then electrochemically oxidized into rose-petal-like mesoporous MnO2 structure. Such a 3D MnO2/VACNF hybrid architecture provides enhanced ion diffusion throughout the whole MnO2 shell and yields excellent current collection capability through the VACNF electrode. These two effects collectively enable faster electrochemical reactions during charge-discharge of MnO2 in 1 M Na2SO4. Thick MnO2 shells (up to 200 nm in radial thickness) can be employed, giving a specific capacitance up to 437 F g(-1). More importantly, supercapacitors employing such a 3D MnO2/VACNF hybrid electrode illustrate more than one order of magnitude higher specific power than the state-of-the-art ones based on other MnO2 structures, reaching ∼240 kW kg(-1), while maintaining a comparable specific energy in the range of 1 to 10 Wh kg(-1). This hybrid approach demonstrates the potential of 3D core-shell architectures for high-power energy storage devices.
一项基于在高导电性三维模板（垂直排列的碳纳米纤维，即VACNFs）上形成厚介孔MnO₂壳层来开发高功率超级电容器材料的研究。将标称厚度为100至600纳米的同轴锰壳层溅射涂覆在VACNFs上，然后进行电化学氧化，形成玫瑰花瓣状的介孔MnO₂结构。这种三维MnO₂/VACNF混合结构在整个MnO₂壳层中增强了离子扩散，并通过VACNF电极产生了出色的电流收集能力。这两种效应共同使得MnO₂在1 M Na₂SO₄中充放电时的电化学反应更快。可以使用厚MnO₂壳层（径向厚度可达200纳米），比电容高达437 F g⁻¹。更重要的是，采用这种三维MnO₂/VACNF混合电极的超级电容器比基于其他MnO₂结构的现有技术产品的比功率高出一个多数量级，达到约240 kW kg⁻¹，同时在1至10 Wh kg⁻¹的范围内保持相当的比能量。这种混合方法展示了三维核壳结构在高功率储能设备方面的潜力。
