Insight into the Formation and Stability of Solid Electrolyte Interphase for Nanostructured Silicon-Based Anode Electrodes Used in Li-Ion Batteries

Constructing Si/6H-SiC Heterostructure As a High-Performance Anode for Boosting Lithium-Ion Storage

Silicon (Si) anodes offer significant potential due to their high capacity. However, their drastic volume change limits their utility, resulting in a shorter cycling life. In this paper, microsilicon particles and 6H-SiC particles were ball-milled and subsequently coated a layer of amorphous carbon, yielding Si/SiC@C composites. Computational and experimental results reveal that this heterostructure formed between Si and 6H-SiC enhances the electronic conductivity of the Si/SiC@C composites dramatically, as well as the Li ion diffusion rate. Thereby, the Si/6H-SiC heterostructure increases capacity and enhances the rate capability of the Si-based anode. Significantly, the conductivity of Si/SiC@C composites surpasses that of Si@C composites by a factor of around 330. Furthermore, tough, evenly distributed, and electrochemically inert 6H-SiC serves as a rigid framework. By reducing the expansion rate of Si-based anodes and mitigating mechanical stress during cycles, this improves the cycling stability. Additionally, the Si/SiC@C anodes demonstrate superior cycle performance (814.6 mAh g-1 at 1 A g-1 after 400 cycles with capacity retention of 88.0%) and excellent rate capability (762 mAh g-1 at 5 A g-1).

Exploitation of function groups in cellulose materials for lithium-ion batteries applications

Cellulose, an abundant and eco-friendly polymer, is a promising raw material to be used for preparing energy storage devices such as lithium-ion batteries (LIBs). Despite the significance of cellulose functional groups in LIBs components, their structure-properties-application relationship remains largely unexplored. This article thoroughly reviews the current research status on cellulose-based materials for LIBs components, with a specific focus on the impact of functional groups in cellulose-based separators. The emphasis is on how these functional groups can enhance the mechanical, thermal, and electrical properties of the separators, potentially replacing conventional non-renewal material-derived components. Through a meticulous investigation, the present review reveals that certain functional groups, such as hydroxyl groups (-OH), carboxyl groups (-COOH), carbonyl groups (-CHO), ester functions (R-COO-R'), play a crucial role in improving the mechanical strength and wetting ability of cellulose-based separators. Additionally, the inclusion of phosphoric group (-PO3H2), sulfonic group (-SO3H) in separators can contribute to the enhanced thermal stability. The significance of comprehending the influence of functional groups in cellulose-based materials on LIBs performance is highlighted by these findings. Ultimately, this review explores the challenges and perspectives of cellulose-based LIBs, offering specific recommendations and prospects for future research in this area.

Guar Gel Binders for Silicon Nanoparticle Anodes: Relating Binder Rheology to Electrode Performance

Binding agents are a critical component of Si-based anodes for lithium-ion batteries. Herein, we introduce a composite hydrogel binder consisting of carbon black (CB) and guar, which is chemically cross-linked with glutaraldehyde as a means to reinforce the electrode structure during lithiation and improve electronic conductivity. Dynamic rheological measurements are used to monitor the cross-linking reaction and show that rheology plays a significant role in binder performance. The cross-linking reaction occurs at a faster rate and produces stronger networks in the presence of CB, as evidenced from higher gel elastic modulus in guar + CB gels than guar gels alone. Silicon nanoparticle (SiNP) electrodes that use binders with low cross-link densities (t_rxn < 2 days) demonstrate discharge capacities ∼1200 mAh g^-1 and Coulombic efficiencies >99.8% after 300 cycles at 1-C rate. Low cross-link densities likely increase the capacity of SiNP anodes because of binder-Si hydrogen-bonding interactions that accommodate volume expansions. In addition, the cross-linked binder demonstrates the potential for self-healing, as evidenced by an increased elastic modulus after the gel was mechanically fragmented, which may preserve the electrode microstructure during lithiation and increase capacity retention. The composite hydrogel with integrated conductive additives gives promise to a new type of binder for next-generation lithium-ion batteries.