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Recently, the growing demand for high-performing batteries and different environmental challenges (such include global warming and climate change) have increased the requirement and demand for Lithium-ion batteries (LIBs) used in advanced technologies (i.e., electric cars and many others). To meet this increasing demand, there is an urgent need for more advanced technologies and materials. In the pursuit of developing anode materials, silicon has emerged as the utmost favourable choice for the next generation of LIBs, aiming to substitute the commonly used graphite. Carbon is commonly used to render silicon (Si) suitable for use since Si cannot be used directly as the electrode in LIBs. One of the recently discovered techniques in the development of high-performance LIBs is the use of inexpensive, sustainable, renewable, and eco-friendly materials. Agro-waste-derived silicon and carbon are often used as long as they don't negatively affect the LIB anode's performance. This review paper presents the advances in the development of silicon-carbon (Si/C) composite anodes sourced from agro-waste for applications in LIBs. It provides an overview of agro-waste-derived silicon-based anode materials and techniques for extracting silica from agricultural wastes. Next, the outline explains the preparation technique of Si/C composites obtained from agricultural residues for use in LIBs. Additionally, the paper delves into recent research challenges and the potential prospects of materials derived from agro-waste in the advancement of sophisticated LIBs battery materials.

Silicon-based photovoltaic technology is helpful in reducing the cost of power generation; however, it suffers from economic losses and environmental pollution caused by silicon cutting waste. Herein, a hydrothermal method accompanied by heat treatment is proposed to take full advantage of the photovoltaic silicon cutting waste and biomass excrementum bombycis to fabricate flake-like porous Si@C (FP-Si@C) composite anodes for lithium-ion batteries (LIBs). The resulting FP-Si@C composite with a meso-macroporous structure can buffer the severe volume changes and facilitate electrolyte penetration. Meanwhile, the slightly graphitic carbon with high electrical conductivity and mechanical strength tightly surrounds the Si nanoflakes, which not only contributes to the ion/electron transport but also maintains the electrode structural integrity during the repeated lithiation/delithiation process. Accordingly, the synergistic effect of the unique structure of FP-Si@C composite contributes to a high discharge specific capacity of 1322 mAh g−1 at 0.1 A g−1, superior cycle stability with a capacity retention of 70.8% after 100 cycles, and excellent rate performance with a reversible capacity of 406 mAh g−1 at 1.0 A g−1. This work provides an easy and cost-effective approach to achieving the high-value application of photovoltaic silicon cutting waste, as well as obtaining high-performance Si-based anodes for LIBs.

Silicon/mesoporous carbon (Si/MC) composites with optimum Si content, in which the volumetric energy density would be maximized, while volume changes would be minimized, have been developed. The composites were prepared by dispersing Si nanoparticles in a phenolic resin as a carbon source, subsequent carbonization, and etching with hydrofluoric acid (HF). Special attention was paid to understanding the role of HF etching as post-treatment to provide additional void spaces in the composites. The etching process was shown to reduce the SiO2 native layer on the Si nanoparticles, resulting in increased porosity in comparison to the non-etched composite material. For cell optimization, vinylene carbonate (VC) was employed as an electrolyte additive to build a stable solid electrolyte interphase (SEI) layer on the electrode. The composition of the SEI layer on Si/MC electrodes, cycled with and without VC-containing electrolytes for several cycles, was then comprehensively investigated by using ex-situ XPS. The SEI layers on the electrodes working with VC-containing electrolyte were more stable than those in configurations without VC; this explains why our sample with VC exhibits lower irreversible capacity losses after several cycles. The optimized Si/MC composites exhibit a reversible capacity of ~800 mAhg−1 with an average coulombic efficiency of ~99 % over 400 cycles at C/10.