Two step pyrolysis synthesis method of graphite-enhanced Nano-Si/Pitch composite as long cycle life anode for lithium-ion batteries

Abstract

Energy storage devices have become the dominant power source in various fields due to their capacity, lifespan, and eco-friendliness. However, there is a need to develop new energy storage devices with higher energy and power density to meet increasing energy demands. Silicon-based anode materials have considerable potential for developing long-lasting, high-capacity energy storage devices, specifically lithium-ion batteries. However, the practical use of these batteries faces challenges like significant volume variations, silicon instability during charging and discharging, and restricted conductivity. This work used silicon nanoparticles from waste industrial solar cells and mixed them with pitch derived from coal tar in a tetrahydrofuran (THF) solvent to form a homogenous Si@Pitch nanocomposite. Pitch-derived carbon helps hold the silicon particles together, reducing the detrimental effects of volume expansion. It acts as a matrix that accommodates the structural changes in silicon during lithiation and delithiation. The Pyrolyzed Si@Pitch-2:1 nanocomposite electrode developed through an efficient two-step pyrolysis technique demonstrated outstanding performance. When charged at a rate of 500 mA·g−1 over 200 cycles, it showed a high discharge capacity of 1524 mAh·g−1, with an average coulombic efficiency of 99.8% and a discharge capacity retention of 75.7%. Combining silicon nanoparticles and pitch derived from recycled industrial waste contributes to the impressive results. This efficient synthesis method can improve the anode materials used in lithium-ion batteries.