Cross‐Linked Chitosan as a Polymer Network Binder for an Antimony Anode in Sodium‐Ion Batteries

Abstract

the limited content of Sb in the composites and the low capacity of carbon materials.Polymer binders that contain carboxyl groups and their derivatives, such as poly(acrylic acid) and sodium carboxymethyl cellulose (CMC), have been reported to suppress suffi ciently the reduction of electrolytes and, therefore, to enable better electrochemical performances of anode materials for sodiumion batteries than the polymer binder of poly(vinylidene fl uoride) (PVDF). [25][26][27][28] However, the repeated volume change of alloy-type anodes during sodiation/desodiation reactions can induce sliding of the chains of linear polymer binders. As a result, irreversible deformations of the polymer chains occur repeatedly with the degradation of mechanical and electrical integrity of the electrode structures. The application of crosslinked polymer binders was previously demonstrated as an effi cient approach to accommodate the extreme volume change of silicon anodes in lithium-ion batteries during lithiation/ delithiation reactions. [29][30][31][32][33][34][35][36] Herein, a novel polymer network consisting of cross-linked chitosan was designed as a polymer binder to immobilize Sb particles in the anode for sodium-ion batteries. The cross-linked chitosan polymer network can effectively suppress the adverse mechanical effect from the large volume expansion and therefore enhance the electrochemical performance of the Sb anode in sodium-ion batteries.As the second most abundant polymer in nature after cellulose, chitin and its deacetylated derivative of chitosan, are carbohydrate-based linear polymers composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit) ( Figure 1 A). [ 37 ] Upon dissolution of chitosan in dilute acetic acid solution, the resulting aqueous solution has a light yellow color. After addition of glutaraldehyde to the chitosan solution, the pale yellow solution becomes a darker yellow color. This is a qualitative indicator of the cross-linking reaction between glutaraldehyde and chitosan with the formation of a cross-linked polymeric network architecture that brings about the sol-gel phase transition of the chitosan solution ( Figure S1A, Supporting Information). The condensation reaction between the amino groups of chitosan and the aldehyde groups of glutaraldehyde with the formation of an amine bond is generally considered responsible for the cross-linking of the two components (Figure 1 B). [ 38 ] The weight fraction of chitosan in the solution is 2% to ensure a good fl uidity. Therefore, about 98% water was trapped in the cross-linked chitosan gelatin even after a small amount of glutaraldehyde was introduced, revealing a large percent of free space available to store materials in the polymer network.Fourier transform-infrared (FT-IR) spectroscopy was conducted to verify the reaction between chitosan and glutaraldehyde. The spectra of chitosan reveal an absorption band at 3400 cm −1 because of the O-H stretching vibration; whereas the band at B...

Electrolytes, SEI Formation, and Binders: A Review of Nonelectrode Factors for Sodium‐Ion Battery Anodes

“…Goodenough and co‐workers also reported the use of a cross‐linked chitosan binder for use with a Sb‐based alloy . Instead of using CMC, the authors relied on chitin and its deacetylated derivative of chitosan, as the basis for the binder.…”

Emerging Prototype Sodium‐Ion Full Cells with Nanostructured Electrode Materials

“…As a typical NASICON structure material, Na 3 V 2 (PO 4 ) 3 (NVP) is widely deemed to be a promising candidate for SIFCs, owing to the stable open‐frameworks structure and high operating voltage of 3.4 V . Jian et al reported the detailed structure of rhombohedral Na 3 V 2 (PO 4 ) 3 and its sodium extracted phase of NaV 2 (PO 4 ) 3 .…”

“…As a typical NASICON structure material, Na 3 V 2 (PO 4 ) 3 (NVP) is widely deemed to be a promising candidate for SIFCs, owing to the stable open-frameworks structure and high operating voltage of 3.4 V. [87][88][89][90] Jian et al [91] reported the detailed structure of rhombohedral Na 3 V 2 (PO 4 ) 3 and its sodium extracted phase of NaV 2 (PO 4 ) 3 . It is confirmed that there are two different types of Na sites (6b, M1 and 18e, M2) with different coordination environments in www.small-journal.com 3 .…”

Nature‐Inspired Electrochemical Energy‐Storage Materials and Devices

“…[81][82][83][84][85][86][87][88] In a standard rechargeable battery, energy-storage relevant materials including electrochemically active materials, binder and separator are usually adopted. [89][90][91][92] Inspired by natural systems, scientists have made great progress in the development of these materials in recent years. [93][94][95][96] More specifically, some redox-active molecules and electron shuttles belonging to the biological extracellular electron transfer chains for active respiration have inspired the construction of active electrode materials containing identical redox-active groups.…”