Effect of Nano-Fillers on Capacity Retention and Rate Capability of Mesocarbon Microbeads Anode

Thin film mesocarbon microbeads (MCMB) composite electrodes consisting of hybrid nano-fillers of carbon black (CB) and carbon nanotubes (CNT) have been developed and characterized by evaluating their electrical and electrochemical properties. The composite electrodes have been fabricated with various weight fractions of CB and CNT. It is shown that by partial replacement of CB by CNT in electrodes, a synergistic improvement in electrical conductivity, initial capacity and stability in cycling behavior at low (0.25C) as well as at high rates (4C) is achievable. This is attributed to the combined effect of (i) hybrid of CB-CNT providing short- and long-range conducting pathways by effectively filling the gaps between MCMB-MCMB, CNT-CNT and MCMB-CNT clusters, and (ii) formation of a compact and stable solid-electrolyte film resulting in a compact three-dimensional conducting scaffold. The electrodes with CB-CNT hybrid additives exhibit best performance in terms of capacity retention (342.8 mAhg−1 after 50 cycles with almost 98% capacity retention at 0.25C and 280.0 mAhg−1 after 100 cycles at 4C) and rate capability. This kind of approach to create a hybrid of geometrically distinct shape, aspect ratio and dispersion characteristics conducting fillers manifests a promising strategy to develop improved performance composite anodes for future lithium-ion batteries.