Core-shell Si@c-PAN particles deposited on graphite as promising anode for lithium-ion batteries

Abstract

In this study, a three-dimensional silicon@cyclized-polyacrylonitrile@graphite (Si@c-PAN@G) nanocomposite structure, consisting of core-shell Si(core)@c-PAN(shell) deposited on a graphite matrix, is fabricated using simple high-energy ball milling (HEBM) followed by heat-treatment. As an anode material for lithium-ion batteries, which is a thin layer (similar to 2.5 nm) of c-PAN coated on Si nanoparticles, it efficiently accommodates a large volume change of Si particles, inhibiting the pulverization and maintaining an appropriate contact with the current collector. At the same time, the graphite functions as a matrix for Si@c-PAN nanoparticles, which not only prevents the agglomeration of Si@c-PAN particles, but also provides an efficient electron transport during cycling, resulting in an outstanding electrochemical performance for Si@c-PAN@G. This novel electrode exhibits an excellent initial capacity (similar to 1580 mAh g(-1) at 0.2 A g(-1) with a coulombic efficiency of 79%), highly stable cyclic performances (1422 mAh g(-1) at 0.2 A g(-1) with capacity retention of 90% after 50 cycles and 1071 mAh g(-1) at 1 A g(-1) with capacity retention of 85% after 100 cycles), high rate capability (capacity retention of similar to 95% at 3.0 A g(-1) compared with the capacity at 0.2 A g(-1)), and low charge transfer resistance (<30 Omega) compared with other Si-based composite electrodes. To achieve these, a new post-annealing strategy for electrode film, the appropriate binder and the optimum weight ratio between c-PAN and graphite are further investigated. (C) 2018 Elsevier Ltd. All rights reserved.