Design of a Bioinspired Robust Three-Dimensional Cross-Linked Polymer Binder for High-Performance Li-Ion Battery Applications

Construction of Protein-Like Helical-Entangled Structure in Lithium-Ion Silicon Anode Binders via Helical Recombination and Hofmeister Effect

In this study, a novel gelatin-xanthan gum composite binder is successfully developed with a protein-like helical-entangled network structure through thermo-responsive and Hofmeister effect to improve the cycling stability of silicon anodes in lithium-ion batteries. As the temperature changes, the molecular chains of xanthan gum and gelatin undergo de-helixing, intertwining, and co-helixing, ultimately self-assembling into a protein-like spatial structure. Furthermore, immersing in Hofmeister salt solution enhances the degree of helical entanglement, significantly improving strength and toughness. This novel helical-entangled structure absorbs and dissipates the stress and strain caused by silicon volume expansion through repeated bending, twisting, and stretching, similar to protein spatial structures, thereby maintaining the integrity of the silicon anode and enhancing its cycling stability. The silicon anode with the optimized binder exhibits high initial Coulombic efficiency, favorable rate performance, and long-term cycling stability. At a current density of 0.5 A g⁻¹, the silicon anode has a specific capacity of 1779.8 mAh g⁻¹ after 300 cycles, with a capacity retention rate of 80.65%. This study demonstrates the feasibility of natural polymers forming complex 3D network structures through self-assembly and intermolecular forces, providing a new approach for the design of silicon anode binders.

Enhancing Stability and 6C Fast Charging in µSi||LiNi0.8Co0.1Mn0.1O2 Lithium-Ion Batteries Using Conductive Binders With Multiple Hydrogen Bonds

Micro-sized silicon (µSi) anodes are an attractive alternative to graphite for high-energy lithium-ion batteries (LIBs) due to their low cost and high specific capacity. However, they suffer from severe volume expansion during lithiation, leading to fast capacity decay and poor rate capability. Herein, a new hybrid binder featuring a cross-linked conductive network and multiple hydrogen bonds for µSi anodes with high areal capacity is reported. This binder demonstrates multi-scale synergistic effects, including robust binder-derived solid electrolyte interphase, multiple networks to mitigate electrode pulverization and efficient ion/electron transfer pathways. As a result, the µSi anodes exhibit long-term cyclability and exceptional rate performance, achieving a high specific capacity of 1481.3 mAh g-1 at 12 A g-1 and maintaining 960.5 mAh g-1 at 20 A g-1. When paired with the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the µSi||NCM811 full cell delivers an impressive capacity of 145.8 mAh g-1 under fast 6C charging conditions, along with high Coulombic efficiency during cycling. This research presents an effective strategy for enabling fast charging and stable cycling in high-energy µSi-based LIBs.

Algae-Based Biopolymers for Batteries and Biofuel Applications in Comparison with Bacterial Biopolymers-A Review

Algae-based biopolymers can be used in diverse energy-related applications, such as separators and polymer electrolytes in batteries and fuel cells and also as microalgal biofuel, which is regarded as a highly renewable energy source. For these purposes, different physical, thermochemical, and biochemical properties are necessary, which are discussed within this review, such as porosity, high temperature resistance, or good mechanical properties for batteries and high energy density and abundance of the base materials in case of biofuel, along with the environmental aspects of using algae-based biopolymers in these applications. On the other hand, bacterial biopolymers are also often used in batteries as bacterial cellulose separators or as biopolymer network binders, besides their potential use as polymer electrolytes. In addition, they are also regarded as potential sustainable biofuel producers and converters. This review aims at comparing biopolymers from both aforementioned sources for energy conversion and storage. Challenges regarding the production of algal biopolymers include low scalability and low cost-effectiveness, and for bacterial polymers, slow growth rates and non-optimal fermentation processes often cause challenges. On the other hand, environmental benefits in comparison with conventional polymers and the better biodegradability are large advantages of these biopolymers, which suggest further research to make their production more economical.