Surface related differences between uncoated versus carbon-coated silicon nanowire electrodes on performance in lithium ion batteries. (February 2020)

• Record Type: Journal Article
• Authors: Krause, Andreas; Langklotz, Ulrike; Pohl, Diana; Tkacheva, Olga; Pohl, Darius; Nielsch, Kornelius; Mikolajick, Thomas; Weber, Walter M.
• Is Part Of: Journal of energy storage. Volume 27(2020)
• Publication Date: 2020-02
• Subjects: Silicon nanowires -- Conductive carbon coating -- Lithium ion batteries -- High capacity -- Surface properties -- Scanning electron microscopy; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2019.101052
• Languages: English
• ISSNs: 2352-152X

Abstract

Highlights: Silicon nanowires are homogenously coated with a conductive carbon coating. Direct comparison of uncoated and carbon coated silicon nanowires reveal new insides. Carbon surface affects the chemical decomposition of electrolytes by potential shift. An increased surface stability is counteracted by additional diffusion barrier. Abstract: We present electrode assemblies of Si nanowires (NW) partially coated with a highly conductive nano-graphitic carbon layer. The surface modifications and overall electrode performance of these electrodes are investigated at high charge and discharge rates. The possibility to directly compare carbon-coated with uncoated SiNW electrodes allows to systematically separate the influences of Si and C on the battery performance and stability from a typically mixed system in electrodes. Consequently, a nanometer thin carbon layer is found to be efficient in withstanding mechanical stress and cracking during battery cycling. Moreover, the protective layer reduces the surface reactivity towards the electrolyte and enhances the electrode conductivity. On the other hand, we conclude that thicker carbon coatings reduce the performance of the Si nanowire network at high currents by introducing an additional diffusion barrier for Li ions. Graphical abstract: Image, graphical abstract