High fractal-dimensional carbon conductive agent for improving the Li storage performance of Si-based electrode

Constructing stable Si electrodes with high areal capacity is crucial for improving the total energy density of lithium ion batteries (LIBs). However, it remains challenging because the poor intrinsic conductivity and serious pulverization of Si usually lead to the active material falling -off from the conductive network. Herein, we demonstrate novel spatially extended graphene ribbons with a high fractal-dimension structure (HFGR-400), which can construct highly conductive and mechanically reinforced networks when used as the conductive agent for Si electrodes. The HFGR-400 added electrode shows 1.5-3.2 times higher conductivity and 1.4-2.3 times larger peeling strength than those of the commonly used carbon conductive agent added electrodes. Moreover, the flexible HFGR-400 ribbons with appropriate amount of functional groups ensure large contact area and strong interfacial interaction with Si particles, but without blocking the ion transport channels. Therefore, the HFGR-400 added Si electrode exhibits good cycle stability (2051.8 mAh/g after 200 cycles) and high rate performance. Moreover, the high Si mass loading HFGR-400 electrode shows a competitive areal capacity of 3.5 mAh cm -2 after 200 cycles, superior to most of the reported Si-based electrodes. Our work highlights the importance of conductive agents with high fractal-dimension structure for practical Si-based electrodes.