Spatially Confined Silicon Nanoparticles Anchored in Porous Carbon as Lithium-Ion-Battery Anode Materials

Abstract

Spatial confinement of silicon (Si) within carbonaceous materials has been regarded as the typical strategy to solve the pulverization and capacity decay of the Si-based electrodes for lithium-ion batteries. However, the uneven distribution of Si particles in the carbon (C) matrix often diminishes the full benefits of Si/C composites to cause instability of the capacity and rate properties. Herein, we fabricate polyacrylamide (PAM) hydrogel-derived porous C with a unique gridding structure to encapsulate the Si particles. The as-fabricated Si@C-PAM electrode with a satisfactory capacity of 1019 mAh g–1 at 0.5 A g–1 after 100 cycles. Even at a current density of 1.0 A g–1, Si@C-PAM still delivers a superior specific capacity of 589 mAh g–1 after 300 cycles with good capacity retention (89%). The fast and stable lithiation/delithiation of Si@C-PAM is attributed to the dense and unobstructed gridding architecture, which offers numerous ion channels for fast charge transfer and seals the Si core sufficiently to accommodate the large volume change. In practical applications, the full-cell LiFePO4/Si@C-PAM also exhibits well reversible capacity. Furthermore, the proposed method provides a good example for many other electrode materials suffering from similar problems.