Highly Densified Fracture-Free Silicon-based Electrode for High Energy Lithium-Ion Batteries

Abstract

There has recently been an increasing volume of research in silicon-based anodes for high energy density lithium-ion batteries. Micron-sized composites with high tap density and a number of pores accommodating the massive volume expansion of silicon (Si) exhibit considerable electrochemical performance with high volumetric energy density. However, huge pressure on the particle during the calendering process brings about mechanical failure which causes the formation of additional by-products upon lithiation and electrical contact loss. Here, we discover specific particle size distribution based on the constructive simulation including calculation of the packing density depending on the different particle size distribution and stress evolution of each particle at high pressure. A silicon/graphite hybrid anode in which the silicon nanolayer (similar to 15 nm) is coated on the graphite is selected to validate the simulation. This anode sustains its morphological integrity and secures its void space without crack propagation of the silicon nanolayer in the densely packed electrode. As a result, it demonstrates high initial specific capacity (>500 mAh g(-1)), high initial Coulombic efficiency (95.2 %), low electrode swelling ratio (35 % at first cycle), and excellent capacity retention ratio (99.1 % during 50 cycles) for high energy density lithium-ion batteries.