“…Compared with BzPz, TzPz shows an expanded the highest occupied molecular orbital (HOMO) diagram distribution on more Pz units, which could be attributed to the higher conjugation degree resulting from the D-A polymer structure of TzPz. [41,51,52] The charge-storage behavior for BzPz and TzPz was investigated by the CV test at different scan rates (Figure S13, Supporting Information). The equation of i = av b could be employed to analyze the charge-storage process, [53][54][55] where i represents the current response in the CV curve, v is the corresponding scan rate, a and b are the parameters.…”
Recent studies have demonstrated that dihydrophenazine (Pz) with high redox-reversibility and high theoretical capacity is an attractive building block to construct p-type polymer cathodes for dual-ion batteries. However, most reported Pz-based polymer cathodes to date still suffer from low redox activity, slow kinetics, and short cycling life. Herein, a donor-acceptor (D-A) Pz-based conjugated microporous polymer (TzPz) cathode is constructed by integrating the electron-donating Pz unit and the electron-withdrawing 2,4,6-triphenyl-1,3,5-triazine (Tz) unit into a polymer chain. The D-A type structure enhances the polymer conjugation degree and decreases the band gap of TzPz, facilitating electron transportation along the polymer skeletons. Therefore the TzPz cathode for dual-ion battery shows a high reversible capacity of 192 mAh g −1 at 0.2 A g −1 with excellent rate performance (108 mAh g −1 at 30 A g −1 ), which is much higher than that of its counterpart polymer BzPz produced from 1,3,5-triphenylbenzene (Bz) and Pz (148 and 44 mAh g −1 at 0.2 and 10 A g −1 , respectively). More importantly, the TzPz cathode also shows a long and stable cyclability of more than 10 000 cycles. These results demonstrate that the D-A structural design is an efficient strategy for developing high-performance polymer cathodes for dual-ion batteries.
“…Compared with BzPz, TzPz shows an expanded the highest occupied molecular orbital (HOMO) diagram distribution on more Pz units, which could be attributed to the higher conjugation degree resulting from the D-A polymer structure of TzPz. [41,51,52] The charge-storage behavior for BzPz and TzPz was investigated by the CV test at different scan rates (Figure S13, Supporting Information). The equation of i = av b could be employed to analyze the charge-storage process, [53][54][55] where i represents the current response in the CV curve, v is the corresponding scan rate, a and b are the parameters.…”
Recent studies have demonstrated that dihydrophenazine (Pz) with high redox-reversibility and high theoretical capacity is an attractive building block to construct p-type polymer cathodes for dual-ion batteries. However, most reported Pz-based polymer cathodes to date still suffer from low redox activity, slow kinetics, and short cycling life. Herein, a donor-acceptor (D-A) Pz-based conjugated microporous polymer (TzPz) cathode is constructed by integrating the electron-donating Pz unit and the electron-withdrawing 2,4,6-triphenyl-1,3,5-triazine (Tz) unit into a polymer chain. The D-A type structure enhances the polymer conjugation degree and decreases the band gap of TzPz, facilitating electron transportation along the polymer skeletons. Therefore the TzPz cathode for dual-ion battery shows a high reversible capacity of 192 mAh g −1 at 0.2 A g −1 with excellent rate performance (108 mAh g −1 at 30 A g −1 ), which is much higher than that of its counterpart polymer BzPz produced from 1,3,5-triphenylbenzene (Bz) and Pz (148 and 44 mAh g −1 at 0.2 and 10 A g −1 , respectively). More importantly, the TzPz cathode also shows a long and stable cyclability of more than 10 000 cycles. These results demonstrate that the D-A structural design is an efficient strategy for developing high-performance polymer cathodes for dual-ion batteries.
“…According to the relationship between peak current densities and scan rates, the b values (Figure 2c ) were calculated as 0.95/0.90 and 0.91/0.92, respectively, indicating a surface‐controlled dominated charge‐storage process. [ 23 , 26 ] The capacitive contribution values (Figure S3a,c , Supporting Information) were determined to be from 82.89% to 91.47% at the scan rates of 2 to 10 mV s −1 . This high surface‐controlled contribution may be attributed to the collaboration interaction of PEDOT and catechol, reflecting the fast kinetics.…”
Aqueous all-polymer proton batteries (APPBs) consisting of redox-active polymer electrodes are considered safe and clean renewable energy storage sources. However, there remain formidable challenges for APPBs to withstand a high current rate while maximizing high cell output voltage within a narrow electrochemical window of aqueous electrolytes. Here, a capacitive-type polymer cathode material is designed by grafting poly(3,4-ethylenedioxythiophene) (PEDOT) with bioinspired redox-active catechol pendants, which delivers high redox potential (0.60 V vs Ag/AgCl) and remarkable rate capability. The pseudocapacitive-dominated proton storage mechanism illustrated by the density functional theory (DFT) calculation and electrochemical kinetics analysis is favorable for delivering fast charge/discharge rates. Coupled with a diffusion-type anthraquinone-based polymer anode, the APPB offers a high cell voltage of 0.72 V, outstanding rate capability (64.8% capacity retention from 0.5 to 25 A g −1 ), and cycling stability (80% capacity retention over 1000 cycles at 2 A g −1 ), which is superior to the state-of-the-art all-organic proton batteries. This strategy and insight provided by DFT and ex situ characterizations offer a new perspective on the delicate design of polymer electrode patterns for high-performance APPBs.
“…PPETQ, the polymer containing the EDOT unit, has a smaller band gap due to its better electron-donating ability, resulting in higher electrical conductivity and a higher HOMO levels (−5.07 eV). Therefore, PPETQ is expected to demonstrate superior reduction properties 30 as the anode materialFigure 6.The CV curves of PPTQ and PPETQ electrodes at a sweep speed of0.1 mV/s.Figure 7.The molecular orbital surfaces of the HOMOs and LUMOs for two monomers.…”
Section: Characterization Results and Discussionmentioning
confidence: 99%
“…PPETQ, the polymer containing the EDOT unit, has a smaller band gap due to its better electron-donating ability, resulting in higher electrical conductivity and a higher HOMO levels (À5.07 eV). Therefore, PPETQ is expected to demonstrate superior reduction properties 30 as the anode material…”
Section: Energy Level Structure Analysismentioning
In this work, thiophene derivatives were selected as donor units and pyrazine derivatives as receptor units to synthesize two composite materials consisting of supercapacitor carbon (SC) loaded with poly [2,3-bis (2-pyridinyl)-5,8-bis (2-thiophenyl) quinoxaline] (PPTQ) or poly [2,3-bis (2-pyridinyl)-5,8-bis (2-(3,4-ethylenedioxythiophene) quinoxaline] (PPETQ) by cationic radical polymerization. First, chemical bonds structure, surface morphology, and element valence states of these materials were characterized by infrared (IR), scanning electron microscopy (SEM) and XPS in turn. CV curves were used to determine their initial oxygen reduction potentials and to calculate their HOMO and LUMO values, both polymers have a narrow band gap, with Eg values lower than 2 eV. The polymer composite materials were tested as anodes in lithium-ion batteries, with a lithium sheet used as the counter electrode. Then the constant current charge-discharge and electrochemical impedance spectroscopy (EIS) impedance were measured. The first discharge specific capacities of PPTQ@SC and PPETQ@SC were 895.9 mAh/g and 913.0 mAh/g at a current density of 100 mA/g, the formation of a SEI film occurred in the second cycle, and their coulomb efficiencies can reach more than 90% from the third cycle, and the discharge platform appeared at about 1.0 V. In contrast, due to its stronger electron-donating ability, the PPETQ polymer containing the 3,4-ethylenedioxythiophene (EDOT) group have better electrical conductivity and its honeycomb structure provides more active sites for the lithiation/delithiation redox process. Therefore, the specific capacity of PPETQ@SC are all higher than that of PPTQ@SC at different current densities.
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