Impact of Binder Functional Groups on Controlling Chemical Reactions to Improve Stability of Rechargeable Zinc-Ion Batteries

Abstract

Rechargeable zinc-ion batteries (ZIBs) are promising alternatives for large-scale energy storage systems. However, instability of the cathode during operation leads to rapid capacity fading and poor stability. Binders play a crucial role in keeping all components in the cathode intact during cycling. However, the impact of the binders’ chemical structure on the electrochemical reaction in ZIBs is not well understood. Herein, the effect of the chemical structure of a conventional polyvinylidene fluoride (PVDF) and green binders, that is, sodium carboxymethyl cellulose (CMC) and cellulose acetate (CA), on the performance, cyclability, and reaction of Zn/α-MnO2 aqueous batteries is investigated. Results show that a cathode having a PVDF binder yields the highest specific capacity in a full battery. Besides, the CMC-based ZIB is seen to attain superior cycling stability through 500 galvanostatic charge–discharge (GCD) cycles having no irreversible products confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is found that the Na+ ion in the CMC structure plays a critical role in promoting prominent battery reactions. The CMC-based ZIB, therefore, is able to maintain its high ionic diffusivity obtained from the galvanostatic intermittent titration technique (GITT) during prolonged operation. Moreover, the interaction between binders and α-MnO2 has been investigated via density-functional theory (DFT) to affirm the high stability of the ZIB/α-MnO2 with the CMC binder. This work highlights the importance of the selection of functional groups on the binder not only to enhance stability but also to control the preferential reactions of batteries. Such findings are ultimate keys for the development of low-cost, stable, and eco-friendly energy storage devices.

Understanding the Role of Polymer Interactions within Binders in Composite Lithium-Ion Anodes

“…In addition to single-component polymeric binders, multicomponent blends offer opportunities to tune the mechanical properties of a composite electrode via deliberate modification of the interconnected networks between particles, which could in turn enhance anode electrochemical performance. Indeed, studies exploring the impact of functional group chemical composition, , polymer molecular weight, , counterion size, cross-linkers, , and plasticizers in binder systems to alter electrochemistry and push toward high-performing anodes have appeared. At a fundamental level, a composite electrode is a percolated network of electroactive particles that act as a chemo-mechanically changing matrix that develops after each lithiation and delithiation cycle.…”

Carboxymethyl cellulose-based materials as an alternative source for sustainable electrochemical devices: a review

“…These batteries have high ionic diffusivity and superior cyclic stability through 500 charge–discharge galvanostatic cycles. 90 Similarly, Yang et al , investigated the influence of CMC as additive for zinc paste electrodes in alkaline zinc batteries. They concluded that an appropriate amount of CMC in alkali can inhibit the zinc dendrite growth with corrosion suppression.…”

Non‐Electrode Components for Rechargeable Aqueous Zinc Batteries: Electrolytes, Solid‐Electrolyte‐Interphase, Current Collectors, Binders, and Separators

“…The challenges and strategies proposed here can be used as a guide for future development: i) Future design of binders for AZBs should consider the physical and chemical properties of active materials, especially for the optimization of the interphase chemistry between active materials and binders. In this respect, theory‐guided elucidation of interactions such as hydrogen bonds, covalent bonds between active materials and binder may provide the atomistic views, which can help screen the suitable binders; [ 172 ] ii) cost and pollution issues associated with the manufacturing process should be carefully taken account of. The assessment of binder performances should be carried out based on the practical testing conditions of large‐scale full cell along with the use of pollution‐free polymers and solvents.…”

“…For instance, binders rich in −OH or −COOH functional groups can form strong hydrogen bonds, and/or covalent bonds with active particles, thereby enhancing the adhesion strength. [172,173] 6. Separators for AZBs…”