Low-cost open-space scaffold structure for high-capacity silicon anode

One of the causes of capacity fading in cells containing silicon anodes is the growth of a secondary SEI. A possible way of solving this problem is to create an anode with a highly porous three-dimensional structure, in which the growing SEI could be accommodated without blocking conduction pathways inside the anode. We evaluated this approach by building a 3D carbon-fiber (CF) scaffold matrix made by the pyrolysis of cotton wool. Anodes fabricated from bare and carbon-coated silicon nanoparticles, were studied from the viewpoint of the influence of anode structure and Li_xSi phase transformations on prolonged cycling of Li/Si cells. Analysis of the mechanisms of degradation of silicon anodes in lithium-ion batteries provides possible ways of elimination of the negative effect of the growth of the SEI on capacity fading. It will be noted that all the anodes containing cotton-carbon fiber matrix exhibit much more stable cycle life than do CF-free anodes. The synthesis of the carbon-fiber (CF) scaffold matrix is simple and easy to scale up to industrial production.