A Quadruple‐Hydrogen‐Bonded Supramolecular Binder for High‐Performance Silicon Anodes in Lithium‐Ion Batteries

Abstract

With extremely high specific capacity, silicon has attracted enormous interest as a promising anode material for next-generation lithium-ion batteries. However, silicon suffers from a large volume variation during charge/discharge cycles, which leads to the pulverization of the silicon and subsequent separation from the conductive additives, eventually resulting in rapid capacity fading and poor cycle life. Here, it is shown that the utilization of a self-healable supramolecular polymer, which is facilely synthesized by copolymerization of tert-butyl acrylate and an ureido-pyrimidinone monomer followed by hydrolysis, can greatly reduce the side effects caused by the volume variation of silicon particles. The obtained polymer is demonstrated to have an excellent self-healing ability due to its quadruple-hydrogen-bonding dynamic interaction. An electrode using this self-healing supramolecular polymer as binder exhibits an initial discharge capacity as high as 4194 mAh g and a Coulombic efficiency of 86.4%, and maintains a high capacity of 2638 mAh g after 110 cycles, revealing significant improvement of the electrochemical performance in comparison with that of Si anodes using conventional binders. The supramolecular binder can be further applicable for silicon/carbon anodes and therefore this supramolecular strategy may increase the choice of amendable binders to improve the cycle life and energy density of high-capacity Li-ion batteries.

A Self‐Healing Integrated All‐in‐One Zinc‐Ion Battery

“…[2] If these energy storage devices have the built-in ability to automatically repair the damage by themselves,t hey can restore the original performance or minimize the performance degradation of the devices. [3] It will not only significantly improve the durability and extend the lifetime of the devices,b ut also reduce the electronic waste and economic cost. [4] Among various aqueous metal-ion batteries,rechargeable Zn-ion batteries (ZIBs) have attracted increasing attention owing to the merits of Zn, such as excellent theoretical capacity (820 mAh g À1 ), high safety,and low cost.…”

“…However,itisnoted that the further increase of Zn(CF 3 SO 3 ) 2 concentration will result in the continuous falling of ionic conductivity owing to the increased viscosity in high-concentration electrolyte,w hich will influence the solvation and transporting behaviors of the cations and anions ( Figure S4, Supporting Information). [6,14] Therefore,t he hydrogels with 2 m Zn(CF 3 SO 3 ) 2 (denoted as Zn(CF 3 SO 3 ) 2 -2 m)d isplay optimal ionic conductivity.F urthermore,s uch ionic conductivity falls slightly,b ut still remains at the same order of magnitude as the original state even after several cutting/selfhealing cycles (Figure 2b), which is vital in the utilization of PVA/Zn(CF 3 SO 3 ) 2 hydrogel as the self-healing electrolyte of ZIBs.F urthermore,P VA /Zn(CF 3…”

Self‐Stabilized and Strongly Adhesive Supramolecular Polymer Protective Layer Enables Ultrahigh‐Rate and Large‐Capacity Lithium‐Metal Anode

“…As demonstrated by the mechanical property tests (Supporting Information, Figures S1-S6), the PEO-UPy polymer is highly self-healable and stretchable, attributing to the quadruple-hydrogen-bonding interactions of UPy dimers. [31,32] Note that PEO-UPy polymer can be dissolved in amixed solvent of 1,3-dioxolane (DOL) and 1,2dimethoxyethane (DME;v olume ratio 1:1), as shown in Figure S7 in the Supporting Information, which could lead to instability and disintegration of the polymer-coating layer once it is directly immersed in electrolytes.I nterestingly,t he polymer can self-stabilize after the contact and reaction with Li metal, which will be discussed later. Furthermore,t he pendant PEO segments can provide an ion-conductive network (with an ionic conductivity of 2.37 10 À5 Scm À1 ;S upporting Information, Figure S8) and homogenize the Li + flux of Li plating/stripping because of the electrostatic interactions between the polar segments and Li ions.T hese unique features render this PEO-UPy supramolecular polymer an appealing artificial SEI for Li metal anodes.…”

Polymer Binders Constructed through Dynamic Noncovalent Bonds for High‐Capacity Silicon‐Based Anodes

“…Am echanically enhanced supramolecular polymer binder formed by quadruple hydrogen bondingw as reported by Deng and co-workers. [41] It is believed that quadruplehydrogen Figure 6. a) The chemical structure of native-XG.…”

“…[41] c) Schematicillustration of the behaviors of PAA-UPy in the lithiation/delithiation process. [41] Chem.E ur.J. 2019, 25,10976 -10994 www.chemeurj.org 2019 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim namic ionically crosslinkedn etwork, the low crosslinking density (mass ratio of CaCl 2 and NaAlg being 1:100) may still cause the relativelyw eaki onic bonding strength, leading to unsatisfactory mechanical performance.…”