Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
Langmuir. 2017 Sep 19;33(37):9407-9415. doi: 10.1021/acs.langmuir.7b01110. Epub 2017 Jun 12.
Composite structures for electrochemical energy storage are prepared on the basis of using the high-rate lithium ion insertion properties of NbO. The NbO is anchored on reduced graphene oxide (rGO) by hydrothermal synthesis to improve the charge-transfer properties, and by controlling the surface charge, the resulting NbO-rGO particles are attached to a high-surface-area carbide-derived carbon scaffold without blocking its exfoliated layers. The electrochemical results are analyzed using a recently published multiscale physics model that provides significant insights regarding charge storage kinetics. In particular, the composite electrode exhibits surface-confined charge storage at potentials of <1.7 V (vs Li/Li), where faradaic processes dominate, and electrical double layer charge storage at potentials of >2.2 V. A hybrid device composed of the composite electrode with activated carbon as the positive electrode demonstrates increased energy density at power densities comparable to an activated carbon device, provided the hybrid device operates in the faradaic potential range.
用于电化学储能的复合结构是基于利用 NbO 的高倍率锂离子嵌入性能制备的。通过水热合成将 NbO 锚定在还原氧化石墨烯（rGO）上，以改善电荷转移性能，并通过控制表面电荷，使得到的 NbO-rGO 颗粒附着在具有高表面积的碳化硅衍生碳支架上，而不会阻塞其剥离层。使用最近发表的多尺度物理模型对电化学结果进行分析，该模型对电荷存储动力学提供了重要的见解。特别是，复合电极在<1.7 V（相对于 Li/Li）的电势下表现出表面限制的电荷存储，其中法拉第过程占主导地位，而在>2.2 V 的电势下表现出双电层电荷存储。由复合电极和活性炭作为正极组成的混合器件在与活性炭器件相当的功率密度下表现出更高的能量密度，前提是混合器件在法拉第电势范围内运行。
