Highly Processable Covalent Organic Framework Gel Electrolyte Enabled by Side‐Chain Engineering for Lithium‐Ion Batteries

Liu, Ziya; Zhang, Kun; Huang, Guoji; Xu, Bingqing; Hong, You‐lee; Wu, Xiaowei; Nishiyama, Yusuke; Horike, Satoshi; Zhang, Gen; Kitagawa, Susumu

doi:10.1002/anie.202110695

Cited by 57 publications

(26 citation statements)

References 41 publications

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“…Incorporating long alkyl chains into CPF pores, which obstruct nitrogen access, may explain the relatively low surface area of both CPFs. 43 CPF2 shows lower surface area compared to CPF1 attributing longer sidechain in CPF2 compared to CPF1. Both CPFs display a relatively steep rise in N 2 uptake at high relative pressures (P/P 0 > 0.9) and hysteresis upon desorption (Figures S6a and S7a in SI), indicating the presence of mesopores.…”

Section: Resultsmentioning

confidence: 91%

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction

Gupta

Halder

Behere

et al. 2023

ACS Appl. Mater. Interfaces

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Conjugated polymer frameworks (CPFs) have recently sparked tremendous research interest due to their broad potentials in various frontline application areas such as photocatalysis, sensing, gas storage, energy storage, etc. These framework materials, without sidechains or functional groups on their backbone, are generally insoluble in common organic solvents and less solution processable for further device applications. There are few reports on metal-free electrocatalysis, especially oxygen evolution reaction (OER) using CPF. Herein, we have developed two triazine-based donor–acceptor conjugated polymer frameworks by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different sidechains, alkyl and oligoethylene glycol, were rationally introduced into the 3-position of thiophene in the polymer framework to investigate the effect of side-chain functionality on the electrocatalytic property. Both the CPFs demonstrated superior electrocatalytic OER activity and long-term durability. The electrocatalytic performance of CPF2, which achieved a current density of 10 mA/cm2 at an overpotential (η) of 328 mV, is much superior to CPF1, which reached the same current density at an overpotential of 488 mV. The porous and interconnected nanostructure of the conjugated organic building blocks, which allowed for fast charge and mass transport processes, could be attributed to the higher electrocatalytic activity of both CPFs. However, the superior activity of CPF2 compared to CPF1 may be due to the presence of a more polar oxygen-containing ethylene glycol side chain, which enhances the surface hydrophilicity, promotes better ion/charge and mass transfer, and increases the accessibility of the active sites toward adsorption through lower π–π stacking compared to hexyl side chain present in CPF1. The DFT study also supports the plausible better performance toward OER for CPF2. This study confirms the promising potentiality of metal-free CPF electrocatalysts for OER and further sidechain modification to improve their electrocatalytic property.

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Section: Resultsmentioning

confidence: 91%

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction

Gupta

Halder

Behere

et al. 2023

ACS Appl. Mater. Interfaces

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“…Induction of interlayer repulsion by metal ions coordinated to ketoenamine-based COFs has added a new strategy to realize the large-scale exfoliation of COFs . The introduction of side groups in hydrazine COFs has led to enhanced exfoliation by lithiation to serve as a solid electrolyte in Li-ion batteries. , These studies show that weakening of the interlayer stacking forces has still been an open challenge to achieve precise control over the obtained nanosheets. Extensive studies have been conducted in the field of COFs to understand the stacking pattern wherein flat structures with minimal twisting in the building units show the possibility for unidirectional in-plane slipping .…”

Section: Introductionmentioning

confidence: 99%

Manipulation of Covalent Organic Frameworks by Side-Chain Functionalization: Toward Few Layer Nanosheets

Haldar

Michel

et al. 2023

Chem. Mater.

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Recent developments in the field of covalent organic frameworks (COFs) describe the issue of processability. The precise tunability of delamination of such structures to obtain few layered nanosheets by synthetic control has been ventured in this study. Covalent anchoring of a series of linear and branched alkoxy side chains to the backbone of layered covalent organic frameworks was used to achieve this. To support the hypothesis, powder X-ray diffraction studies accompanied by computational modeling revealed that the elongation of side chains increases the interlayer distances of the COFs. This led to a successful study of the solvent-assisted exfoliation by atomic force microscopy techniques to obtain nanosheets with heights less than 2 nm, representing stacks of 4–5 layers. Dispersions of the functionalized COF nanosheets are stable for several hours. Furthermore, the surface properties are drastically changed, rendering the materials hydrophobic, with contact angles reaching up to 142° and complete blockage of the pore space toward water vapor. As a proof of concept, the sheets are processable and could be integrated into separators for lithium-ion batteries.

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“…The Brunauer–Emmett–Teller (BET) surface area of the polymer was measured to be 15.54 m 2 g –1 , which is quite less than the surface area reported in the literature . The incorporation of long ethylene glycol side chains into the polymer framework may occupy the pore space and obstruct the access of nitrogen, resulting in relative surface area . The OPF exhibits a relatively steep rise in N 2 uptake at high relative pressures ( P / P 0 > 0.9) and hysteresis upon desorption, pointing out the presence of mesopores (Figure e) .…”

Section: Resultsmentioning

confidence: 86%

“…44 The incorporation of long ethylene glycol side chains into the polymer framework may occupy the pore space and obstruct the access of nitrogen, resulting in relative surface area. 45 The OPF exhibits a relatively steep rise in N 2 uptake at high relative pressures (P/P 0 > 0.9) and hysteresis upon desorption, pointing out the presence of mesopores (Figure 2e). 46 The pore size distribution (PSD) of the polymer framework reveals the absorption peaks in the 1−10 nm region with an average pore radius of 1.52 nm.…”

Section: Characterization Of the Synthesized Organic Polymer Framewor...mentioning

confidence: 96%

Solid Polymer Electrolyte Based on an Ionically Conducting Unique Organic Polymer Framework for All-Solid-State Lithium Batteries

Bandyopadhyay

Gupta

Joshi

et al. 2023

ACS Appl. Energy Mater.

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Solid polymer electrolytes (SPEs) are regarded as a potential candidate for the development of all-solid-state lithium batteries minus the safety issues related to their liquid counterparts. Poly(ethylene oxide) (PEO)-based SPEs with strong capability to dissolve lithium salts have found extensive application in lithium batteries. However, the crystalline nature and propensity of lithium dendrite growth in such SPEs have led to the search for preemptive alternatives like the incorporation of inorganic nanoparticles or porous frameworks as fillers in the polymer matrix. Herein, a unique organic polymer framework (OPF) was synthesized by the Suzuki–Miyaura coupling reaction between 2,5-dibromo-3-(2-(2-(2-ethoxyethoxy)ethoxy)ethyl)thiophene and triazine-phenyl boronic acid. Interestingly, the incorporation of long ethylene glycol side chains in the polymer framework resulted in the amorphous nature of the OPF. Impressively, the percentage of crystallinity of PEO reduced significantly to only 30% in OPF-incorporated PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) composites. Further, the side chains present in a multidirectional manner acted as an interfacial compatibilizer aiding the homogeneous distribution of OPF in the PEO matrix. The SPE showed significantly improved ionic conductivity compared to the pristine samples (9.61 × 10–3 S cm–1 at 55 °C) and a lithium-ion transference number of 0.53. The performance of such SPE was further evaluated by assembling Li/LiFePO4 (LFP) coin cells, showing a stable discharge capacity of 130 mAh g–1 at 0.2C after 200 cycles. This work provides an interesting concept for building a unique type of homogeneous OPF/PEO-based composite SPE film that can be utilized as a desirable material in solid electrolytes for lithium battery applications.

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Highly Processable Covalent Organic Framework Gel Electrolyte Enabled by Side‐Chain Engineering for Lithium‐Ion Batteries

Cited by 57 publications

References 41 publications

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction

Manipulation of Covalent Organic Frameworks by Side-Chain Functionalization: Toward Few Layer Nanosheets

Solid Polymer Electrolyte Based on an Ionically Conducting Unique Organic Polymer Framework for All-Solid-State Lithium Batteries

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