02574nas a2200313 4500008004100000022001400041245013000055210006900185260000800254300001200262490000700274520150800281653003201789653001501821653002301836653001701859653002101876653002001897100002001917700002101937700002201958700002201980700001802002700001702020700003602037700003002073700003002103856012702133 2021 eng d a1614-683200aExceptional capacitance enhancement of a non-conducting COF through potential-driven chemical modulation by redox electrolyte0 aExceptional capacitance enhancement of a nonconducting COF throu cAPR a20036260 v113 a

Capacitors are the most practical high-storage and rapid charge-release devices. The number of ions stored per unit area and their interaction strength with the electrode dictates capacitor-performance. Microporous materials provide a high storage surface and optimal interactions. Adsorbing electron-rich and easily polarizable molecules into microporous electrodes is expected to boost Faradaic pseudo-activity. If such electrode-electrolyte interactions can be made as a potential-driven reversible process, the resulting capacitors would be adaptable and device-friendly. A composite covalent organic framework (COF)-carbon electrode with redox-active KI is combined in an H2SO4 electrolyte for the first time. This composite electrode benefits from the redox-functionality of COF and electronic conductivity of carbon, leading to superior capacitative activity. Operando spectro-electrochemical measurements reveal the existence of multiple polyiodide species, although the I-3(-) is the predominantly electroactive species adsorbing on the microporous triazine-phenol COF electrode. A systematic fabrication of the flexible solid-state devices using the COF-redox-electrolyte reveals a high areal capacitance of 270 +/- 11 mF cm(-2) and gravimetric capacitance of 57 +/- 8 F g(-1). The inclusion of KI in H2SO4 (electrolyte) yields an approximately eight-fold enhancement in solid-state gravimetric specific capacitance. The imine-COF retains 89% of its capacity even after 10 000 cycles.

10acovalent organic frameworks10apolyiodide10aredox electrolytes10asolid&\#820810astate capacitors10aSupercapacitors1 aKushwaha, Rinku1 aHaldar, Sattwick1 aShekhar, Pragalbh1 aKrishnan, Akshara1 aSaha, Jayeeta1 aHui, Pramiti1 aVinod, Chathakudath, Prabhakara1 aSubramaniam, Chandramouli1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/exceptional-capacitance-enhancement-non-conducting-cof-through-potential-driven-chemical02408nas a2200289 4500008004100000022001400041245011300055210006900168260000800237490000700245520141200252653003201664653002301696653001501719653002301734653002101757100002001778700001801798700002201816700001701838700002701855700001601882700002301898700003601921700003001957856013101987 2023 eng d a1614-683200aMade to measure squaramide COF cathode for zinc dual-ion battery with enriched storage via redox electrolyte0 aMade to measure squaramide COF cathode for zinc dualion battery  cSEP0 v133 a

Aqueous rechargeable batteries are promising grid-scale energy storage devices because of their affordability, operational safety, and environmental benignity. Among these, Zn-ion batteries (ZIBs) have unfolded new horizons. Designing superior cathodes for ZIBs is crucial. Covalent organic frameworks (COFs) can be made redox active with a high storage surface. Here, for the first time, a chelating COF with redox-active ZnI2 in a ZnSO4(aq) electrolyte is combined. Including iodide harvests an approximately threefold enhancement in capacity from 208 to 690 mAh g(-1) at 1.5 A g(-1), the highest among all the COF-derived ZIBs. Remarkably, a charge-discharge curve at 1.3 V exhibits very limited dropout voltage and super-flat platform, with a remarkable capacity of 600 mAh g(-1) at 5 A g(-1) stable up to 6000 cycles, confirming that the polyiodide generation and storage are sustainable. The COF's dual-ion storage (Zn2+ and polyidode) delivers a ZIB with the highest energy density. Spectro-electrochemical measurements coupled with X-ray photoelectron spectroscopy unambiguously unveil the existence of multiple polyiodide species, with I-3(-) and IO3- ions as the prominent species. The latter gets reduced at the COF electrode under an applied potential, leaving I-3(-) as the major species stored on the COF. The prospect of COF-polyiodide((aq)) is a windfall for metal-ion batteries.

10acovalent organic frameworks10aflexible batteries10apolyiodide10aredox electrolytes10aZn ion batteries1 aKushwaha, Rinku1 aJain, Chitvan1 aShekhar, Pragalbh1 aRase, Deepak1 aIllathvalappil, Rajith1 aMekan, Deep1 aCamellus, Augastus1 aVinod, Chathakudath, Prabhakara1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/made-measure-squaramide-cof-cathode-zinc-dual-ion-battery-enriched-storage-redox-electrolyte02347nas a2200265 4500008004100000022001400041245014300055210006900198260000800267300001200275490000800287520138500295653003201680653002801712100001801740700002001758700001701778700002201795700001901817700001901836700003201855700003601887700003001923856012801953 2023 eng d a0002-786300aTailoring COFs: transforming nonconducting 2D layered COF into a conducting quasi-3D architecture via interlayer knitting with polypyrrole0 aTailoring COFs transforming nonconducting 2D layered COF into a  cDEC a487-4990 v1463 a

Improving the electronic conductivity and the structural robustness of covalent organic frameworks (COFs) is paramount. Here, we covalently cross-link a 2D COF with polypyrrole (Ppy) chains to form a quasi-3D COF. The 3D COF shows well-defined reflections in the SAED patterns distinctly indexed to its modeled crystal structure. This knitting of 2D COF layers with conjugated polypyrrole units improves electronic conductivity from 10(-9) to 10(-2 )S m(-1). This conductivity boost is affirmed by the presence of density of states near the Fermi level in the 3D COF, and this elevates the COF's valence band maximum by 0.52 eV with respect to the parent 2D pyrrole-functionalized COF, which agrees well with the opto-electro band gaps. The extent of HOMO elevation suggests the predominant existence of a polaron state (radical cation), giving rise to a strong EPR signal, most likely sourced from the cross-linking polypyrrole chains. A supercapacitor devised with COF20-Ppy records a high areal capacitance of 377.6 mF cm(-2), higher than that of the COF loaded with noncovalently linked polypyrrole chains. Thus, the polypyrrole acts as a ``conjugation bridge'' across the layers, lowering the band gap and providing polarons and additional conduction pathways. This marks a far-reaching approach to converting many 2D COFs into highly ordered and conducting 3D ones.

10acovalent organic frameworks10aElectrical conductivity1 aJain, Chitvan1 aKushwaha, Rinku1 aRase, Deepak1 aShekhar, Pragalbh1 aShelke, Ankita1 aSonwani, Disha1 aAjithkumar, Thalasseril, G.1 aVinod, Chathakudath, Prabhakara1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/tailoring-cofs-transforming-nonconducting-2d-layered-cof-conducting-quasi-3d-architecture