Chitosan-grafted-Gallic Acid as a Nature-Inspired Multifunctional Binder for High-Performance Silicon Anodes in Lithium-Ion Batteries

Abstract

Due to its high theoretical specific capacity and natural abundance, silicon (Si) and its composites are considered to be pivotal anode materials for high-energy-density next-generation lithium-ion batteries (LIBs). However, the significant volume changes during the repeated lithiation/delithiation process cause the loss of electrical contact and the continuous formation of a solid electrolyte interface (SEI), hindering Si’s practical applications. The rational design of the polymer binder is an efficient approach to preserve the electrode’s structure from large Si volume changes, thereby enhancing the cycle performance in lithium-ion batteries. We developed an aqueous binder using a plant-inspired adhesive phenolic moiety, gallic acid (3,4,5-trihydroxybenzoic acid, GA), grafted onto the marine-based polymer, chitosan (CS) by a simple radical reaction. The chitosan-grafted-gallic acid, CS-g-GA, not only improves the water solubility of CS but also achieves enhanced binding properties onto Si, hence contributing to better accommodating the volume expansion of Si during the repeated cycling and also maintaining the structural integrity of the Si electrode electronic made from the CS-g-GA as a binder. Si@CS-GA-100 exhibits excellent high-rate capability and long cycling stability, delivering a high reversible specific capacity of 1868 mAh g–1 with a capacity retention of 67% at a rate of 0.5 C after 350 cycles.

Enhanced Chitosan Photoluminescence by Incorporation of Lithium Perchlorate

“… 1 , 5 , 13 − 17 Adding salt to polymers causes changes in the structure, and in optical, electrical, and thermal properties. 1 , 14 , 18 − 20 In the case of chitosan, it provides ions as charge carriers that can improve the conductivity of the polymer, as has been reported in different works. 1 , 21 , 22 The most used dopants in the preparation of many polymer electrolytes are lithium salts like lithium perchlorate, 19 , 23 , 24 lithium tetraborate, 25 lithium hexafluorophosphate, and lithium trifluoromethanesulfonate.…”

“…Many hydroxyls and amine groups in polymers can act as electron donors, facilitating the reactions with many organic and inorganic salts to form polyelectrolytes. ,,− Adding salt to polymers causes changes in the structure, and in optical, electrical, and thermal properties. ,,− In the case of chitosan, it provides ions as charge carriers that can improve the conductivity of the polymer, as has been reported in different works. ,, The most used dopants in the preparation of many polymer electrolytes are lithium salts like lithium perchlorate, ,, lithium tetraborate, lithium hexafluorophosphate, and lithium trifluoromethanesulfonate. , Lithium salts are preferred due to their low interfacial strength and ability to coordinate and solvate easily, exhibiting their ionic conductivity character. The advantage of incorporating these salts is that a complexation can be obtained when the polymer electrolytes are prepared due to their high dissociation energy and good solubility in most solvents …”

Research progress of robust binders with superior mechanical properties for high-performance silicon-based lithium-ion batteries

“…They can form strong interactions with electrolytes through hydrogen bonds or dipole interactions. To date, there have been many polymer binders, including polyacrylic acid (PAA), 76,79 sodium carboxymethyl cellulose (CMC), 80,81 sodium alginate (SA), 82 polyvinyl alcohol (PVA), 83 guar gum (GG), 84 etc., and bio-polysaccharided derived 54,59,85 with affluent -OH, COOH/COOR have been explored. These binders improve the interaction between its Si-based particles and mitigate the rupture of electrodes during charging and discharging.…”

Multidimensional Branched Composite Binder via Covalent Grafting for High-Performance Silicon-Based Anodes

“…Recently, numerous studies have confirmed that compared with the above linear structure binder, grafting or cross-linking network binders constructed by reasonably designed functional components can well adapt to the huge volume expansion of Si . Grafting modification can increase the active group or form a branched structure, , while cross-linking modification can form a three-dimensional (3D) network structure . These modification methods can reduce irreversible slippage of polymer chains, , thereby contributing to maintain the integrity of Si-based anodes.…”