Pseudocapacitors harness unique charge-storage mechanisms to enable high-capacity, rapidly cycling devices. Here we describe an organic system composed of perylene diimide and hexaazatrinaphthylene exhibiting a specific capacitance of 689 F g−1 at a rate of 0.5 A g−1, stability over 50,000 cycles, and unprecedented performance at rates as high as 75 A g−1. We incorporate the material into two-electrode devices for a practical demonstration of its potential in next-generation energy-storage systems. We identify the source of this exceptionally high rate charge storage as surface-mediated pseudocapacitance, through a combination of spectroscopic, computational and electrochemical measurements. By underscoring the importance of molecular contortion and complementary electronic attributes in the selection of molecular components, these results provide a general strategy for the creation of organic high-performance energy-storage materials.
This is a preview of subscription content
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the findings of this study are available from the corresponding authors upon reasonable request.
Schmidt, O., Hawkes, A., Gambhir, A. & Staffell, I. The future cost of electrical energy storage based on experience rates. Nat. Energy 2, 17110 (2017).
Lu, Y. & Chen, J. Prospects of organic electrode materials for practical lithium batteries. Nat. Rev. Chem. 4, 127–142 (2020).
Pomerantseva, E., Bonaccorso, F., Feng, X., Cui, Y. & Gogotsi, Y. Energy storage: the future enabled by nanomaterials. Science 366, eaan8285 (2019).
Choi, C. et al. Achieving high energy density and high power density with pseudocapacitive materials. Nat. Rev. Mater. 5, 5–19 (2019).
Kim, S. K., Cho, J., Moore, J. S., Park, H. S. & Braun, P. V. High-performance mesostructured organic hybrid pseudocapacitor electrodes. Adv. Funct. Mater. 26, 903–910 (2016).
Boota, M. & Gogotsi, Y. MXene—conducting polymer asymmetric pseudocapacitors. Adv. Energy Mater. 9, 1802917 (2019).
Bryan, A. M., Santino, L. M., Lu, Y., Acharya, S. & D’Arcy, J. M. Conducting polymers for pseudocapacitive energy storage. Chem. Mater. 28, 5989–5998 (2016).
Faulkner, E. B. & Schwartz, R. J. High Performance Pigments 2nd edn (Wiley, 2009).
Lee, S. K. et al. Electrochemistry, spectroscopy and electrogenerated chemiluminescence of perylene, terrylene, and quaterrylene diimides in aprotic solution. J. Am. Chem. Soc. 121, 3513–3520 (1999).
Geng, J., Renault, S., Poizot, P. & Dolhem, F. Search for greener Li-ion batteries: an alternative offered by organic electroactive materials. in Energy Harvesting and Storage: Materials, Devices, and Applications II (eds Dhar, N. K. et al.) 803504 (SPIE, 2011).
Peng, C. et al. Reversible multi-electron redox chemistry of π-conjugated N-containing heteroaromatic molecule-based organic cathodes. Nat. Energy 2, 17074 (2017).
Peurifoy, S. R. et al. Three-dimensional graphene nanostructures. J. Am. Chem. Soc. 140, 9341–9345 (2018).
Schuster, N. J. et al. Electron delocalization in perylene diimide helicenes. Angew. Chem. Int. Ed. 128, 13717–13721 (2016).
Zhong, Y. et al. Helical ribbons for molecular electronics. J. Am. Chem. Soc. 136, 8122–8130 (2014).
Peurifoy, S. R. et al. Dimensional control in contorted aromatic materials. Chem. Rec. 19, 1050–1061 (2019).
Forse, A. C., Griffin, J. M., Presser, V., Gogotsi, Y. & Grey, C. P. Ring current effects: factors affecting the NMR chemical shift of molecules adsorbed on porous carbons. J. Phys. Chem. C 118, 7508–7514 (2014).
Cervini, L. et al. Factors affecting the nucleus-independent chemical shift in NMR studies of microporous carbon electrode materials. Energy Storage Mater. 21, 335–346 (2019).
Matsunaga, T., Kubota, T., Sugimoto, T. & Satoh, M. High-performance lithium secondary batteries using cathode active materials of triquinoxalinylenes exhibiting six electron migration. Chem. Lett. 40, 750–752 (2011).
Haeupler, B., Wild, A. & Schubert, U. S. Carbonyls: powerful organic materials for secondary batteries. Adv. Energy Mater. 5, 1402034 (2015).
Hollas, A. et al. A biomimetic high-capacity phenazine-based anolyte for aqueous organic redox flow batteries. Nat. Energy 3, 508–514 (2018).
Conway, B. E. Transition from “supercapacitor” to “battery” behavior in electrochemical energy storage. J. Electrochem. Soc. 138, 1539 (1991).
Augustyn, V. et al. High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance. Nat. Mater. 12, 518–522 (2013).
Forghani, M. & Donne, S. W. Method comparison for deconvoluting capacitive and pseudo-capacitive contributions to electrochemical capacitor electrode behavior. J. Electrochem. Soc. 165, A664–A673 (2018).
Ardizzone, S., Fregonara, G. & Trasatti, S. “Inner” and “outer” active surface of RuO2 electrodes. Electrochim. Acta 35, 263–267 (1990).
Baronetto, D., Krstajić, N. & Trasatti, S. Reply to “note on a method to interrelate inner and outer electrode areas” by H. Vogt. Electrochim. Acta 39, 2359–2362 (1994).
Lee, J.-S. M., Briggs, M. E., Hu, C.-C. & Cooper, A. I. Controlling electric double-layer capacitance and pseudocapacitance in heteroatom-doped carbons derived from hypercrosslinked microporous polymers. Nano Energy 46, 277–289 (2018).
Li, X.-C. et al. Redox-active triazatruxene-based conjugated microporous polymers for high-performance supercapacitors. Chem. Sci. 8, 2959–2965 (2017).
Lu, Q., Chen, J. G. & Xiao, J. Q. Nanostructured electrodes for high-performance pseudocapacitors. Angew. Chem. Int. Ed. 52, 1882–1889 (2013).
Xu, J. et al. Facile synthesis of novel metal-organic nickel hydroxide nanorods for high performance supercapacitor. Electrochim. Acta 211, 595–602 (2016).
McKeown, N. B. et al. Polymers of intrinsic microporosity (PIMs): bridging the void between microporous and polymeric materials. Chem. Eur. J. 11, 2610–2620 (2005).
Acharya, S. et al. Ultrahigh stability of high-power nanofibrillar PEDOT supercapacitors. Sustain. Energy Fuels 1, 482–491 (2017).
Witomska, S. et al. Graphene oxide hybrid with sulfur–nitrogen polymer for high-performance pseudocapacitors. J. Am. Chem. Soc. 141, 482–487 (2018).
Hou, Z., Yang, Q., Lu, H. & Li, Y. Towards enhanced electrochemical capacitance with self‐assembled synthesis of poly(pyrrole‐co‐o‐toluidine) nanoparticles. J. Appl. Polym. Sci. 133, 42995 (2016).
Kim, S. K., Kim, Y. K., Lee, H., Lee, S. B. & Park, H. S. Superior pseudocapacitive behavior of confined lignin nanocrystals for renewable energy‐storage materials. ChemSusChem 7, 1094–1101 (2014).
Park, S. K. et al. 105 cyclable pseudocapacitive Na-ion storage of hierarchically structured phosphorus-incorporating nanoporous carbons in organic electrolytes. ACS Energy Lett. 3, 724–732 (2018).
Feng, D. et al. Robust and conductive two-dimensional metal−organic frameworks with exceptionally high volumetric and areal capacitance. Nat. Energy 3, 30–36 (2018).
Rajasingh, P., Cohen, R., Shirman, E., Shimon, L. J. & Rybtchinski, B. Selective bromination of perylene diimides under mild conditions. J. Org. Chem. 72, 5973–5979 (2007).
Wang, J., Lee, Y., Tee, K., Riduan, S. N. & Zhang, Y. A nanoporous sulfur-bridged hexaazatrinaphthylene framework as an organic cathode for lithium ion batteries with well-balanced electrochemical performance. Chem. Commun. 54, 7681–7684 (2018).
Yu, W. et al. Discovery of fused tricyclic core containing HCV NS5A inhibitors with pan-genotype activity. Bioorg. Med. Chem. Lett. 26, 3158–3162 (2016).
Vitaku, E. et al. Phenazine-based covalent organic framework cathode materials with high energy and power densities. J. Am. Chem. Soc. 142, 16–20 (2019).
Sisto, T. J. et al. Long, atomically precise donor–acceptor cove-edge nanoribbons as electron acceptors. J. Am. Chem. Soc. 139, 5648–5651 (2017).
Peurifoy, S. R. et al. Designing three-dimensional architectures for high-performance electron accepting pseudocapacitors. J. Am. Chem. Soc. 140, 10960–10964 (2018).
Shen, Z., Cao, L., Rahn, C. D. & Wang, C.-Y. Least squares galvanostatic intermittent titration technique (LS-GITT) for accurate solid phase diffusivity measurement. J. Electrochem. Soc. 160, A1842 (2013).
Xu, B. et al. Activated carbon with high capacitance prepared by NaOH activation for supercapacitors. Mater. Chem. Phys. 124, 504–509 (2010).
Muench, S. et al. Polymer-based organic batteries. Chem. Rev. 116, 9438–9484 (2016).
Li, H. et al. A high-performance sodium-ion hybrid capacitor constructed by metal–organic framework–derived anode and cathode materials. Adv. Energy Mater. 28, 1800757 (2018).
Zheng, J. P. The limitations of energy density of battery/double-layer capacitor asymmetric cells. J. Electrochem. Soc. 150, A484 (2003).
Bochevarov, A. D. et al. Jaguar: a high‐performance quantum chemistry software program with strengths in life and materials sciences. Int. J. Quantum Chem. 113, 2110–2142 (2013).
Lee, S. W. et al. High-power lithium batteries from functionalized carbon-nanotube electrodes. Nat. Nanotechnol. 5, 531–537 (2010).
Zeng, L. et al. Carbonaceous mudstone and lignin-derived activated carbon and its application for supercapacitor electrode. Surf. Coat. Technol. 357, 580–586 (2019).
Su, X.-L. et al. Three-dimensional porous activated carbon derived from loofah sponge biomass for supercapacitor applications. Appl. Surf. Sci. 436, 327–336 (2018).
Wang, Y., Tao, S., An, Y., Wu, S. & Meng, C. Bio-inspired high performance electrochemical supercapacitors based on conducting polymer modified coral-like monolithic carbon. J. Mater. Chem. A 1, 8876–8887 (2013).
Kim, M., Lee, C. & Jang, J. Fabrication of highly flexible, scalable, and high-performance supercapacitors using polyaniline/reduced graphene oxide film with enhanced electrical conductivity and crystallinity. Adv. Funct. Mater. 24, 2489–2499 (2014).
Milczarek, G. & Inganäs, O. Renewable cathode materials from biopolymer/conjugated polymer interpenetrating networks. Science 335, 1468–1471 (2012).
Bachman, J. C. et al. Electrochemical polymerization of pyrene derivatives on functionalized carbon nanotubes for pseudocapacitive electrodes. Nat. Commun. 6, 7040 (2015).
Li, M. & Yang, L. Intrinsic flexible polypyrrole film with excellent electrochemical performance. J. Mater. Sci. Mater. Electron. 26, 4875–4879 (2015).
Grover, S. et al. Polyaniline all solid-state pseudocapacitor: role of morphological variations in performance evolution. Electrochim. Acta 196, 131–139 (2016).
Su, D., Zhang, J., Dou, S. & Wang, G. Polypyrrole hollow nanospheres: stable cathode materials for sodium-ion batteries. Chem. Commun. 51, 16092–16095 (2015).
Cong, H.-P., Ren, X.-C., Wang, P. & Yu, S.-H. Flexible graphene–polyaniline composite paper for high-performance supercapacitor. Energy Environ. Sci. 6, 1185–1191 (2013).
Cai, Z. et al. Flexible, weavable and efficient microsupercapacitor wires based on polyaniline composite fibers incorporated with aligned carbon nanotubes. J. Mater. Chem. A 1, 258–261 (2013).
Shen, K. et al. Supercapacitor electrodes based on nano-polyaniline deposited on hollow carbon spheres derived from cross-linked co-polymers. Synth. Met. 209, 369–376 (2015).
Wang, S. et al. Free-standing 3D graphene/polyaniline composite film electrodes for high-performance supercapacitors. J. Power Sources 299, 347–355 (2015).
Sun, H. et al. A self-standing nanocomposite foam of polyaniline@reduced graphene oxide for flexible super-capacitors. Synth. Met. 209, 68–73 (2015).
Wang, Z., Tammela, P., Zhang, P., Strømme, M. & Nyholm, L. High areal and volumetric capacity sustainable all-polymer paper-based supercapacitors. J. Mater. Chem. A 2, 16761–16769 (2014).
Seok, J. Y., Lee, J. & Yang, M. Self-generated nanoporous silver framework for high-performance iron oxide pseudocapacitor anodes. ACS Appl. Mater. Interfaces 10, 17223–17231 (2018).
Pan, Z. et al. In situ growth of layered bimetallic ZnCo hydroxide nanosheets for high-performance all-solid-state pseudocapacitor. ACS Nano 12, 2968–2979 (2018).
Pang, H. et al. Cu superstructures fabricated using tree leaves and Cu–MnO2 superstructures for high performance supercapacitors. J. Mater. Chem. A 1, 5053–5060 (2013).
Ding, K., Zhang, X., Li, J., Yang, P. & Cheng, X. Phase and morphology evolution of ultrathin Co(OH)2 nanosheets towards supercapacitor application. CrystEngComm 19, 5780–5786 (2017).
Song, Y. et al. A polyanionic molybdenophosphate anode for a 2.7 V aqueous pseudocapacitor. Nano Energy 65, 104010 (2019).
Chen, H. et al. One-step fabrication of ultrathin porous nickel hydroxide-manganese dioxide hybrid nanosheets for supercapacitor electrodes with excellent capacitive performance. Adv. Energy Mater. 3, 1636–1646 (2013).
Qiu, K. et al. Mesoporous, hierarchical core/shell structured ZnCo2O4/MnO2 nanocone forests for high-performance supercapacitors. Nano Energy 11, 687–696 (2015).
Wu, M.-S. & Wu, J.-F. Nickel hydroxide electrode with porous nanotube arrays prepared by hydrolysis and cathodic deposition for high-performance supercapacitors. J. Power Sources 240, 397–403 (2013).
Soltanloo, M., Kazazi, M., Yeganeh, S. E. H., Chermahini, M. D. & Mazinani, B. High-performance pseudocapacitive electrode based on electrophoretically deposited NiCo2O4/MWCNTs nanocomposite on 316L stainless steel. JOM 72, 2235–2244 (2020).
Liu, X. et al. Multi-shelled Ni6MnO8 hollow microspheres for high-performance supercapacitors. Mater. Res. Express 7, 065502 (2020).
Yang, G.-W., Xu, C.-L. & Li, H.-L. Electrodeposited nickel hydroxide on nickel foam with ultrahigh capacitance. Chem. Commun. https://doi.org/10.1039/B815647F (2008).
Gupta, A. K., Saraf, M., Bharadwaj, P. K. & Mobin, S. M. Dual functionalized CuMOF-based composite for high-performance supercapacitors. Inorg. Chem. 58, 9844–9854 (2019).
Chen, G.-F., Liu, Z.-Q., Lin, J.-M., Li, N. & Su, Y.-Z. Hierarchical polypyrrole based composites for high performance asymmetric supercapacitors. J. Power Sources 283, 484–493 (2015).
Jagadale, A. D. et al. Cobalt hydroxide [Co(OH)2] loaded carbon fiber flexible electrode for high performance supercapacitor. RSC Adv. 5, 56942–56948 (2015).
Wang, H., Casalongue, H. S., Liang, Y. & Dai, H. Ni(OH)2 nanoplates grown on graphene as advanced electrochemical pseudocapacitor materials. J. Am. Chem. Soc. 132, 7472–7477 (2010).
Li, L., Chen, L., Qian, W., Xie, F. & Dong, C. Directly grown multiwall carbon nanotube and hydrothermal MnO2 composite for high-performance supercapacitor electrodes. Nanomaterials 9, 703 (2019).
Zhang, F. et al. A high-performance supercapacitor-battery hybrid energy storage device based on graphene-enhanced electrode materials with ultrahigh energy density. Energy Environ. Sci. 6, 1623–1632 (2013).
Ma, H. et al. Disassembly–reassembly approach to RuO2/graphene composites for ultrahigh volumetric capacitance supercapacitor. Small 13, 1701026 (2017).
Wang, Y. et al. Ultrathin NiCo-MOF nanosheets for high-performance supercapacitor electrodes. ACS Appl. Energy Mater. 2, 2063–2071 (2019).
Zhai, T. et al. Phosphate ion functionalized Co3O4 ultrathin nanosheets with greatly improved surface reactivity for high performance pseudocapacitors. Adv. Mater. 29, 1604167 (2017).
Sun, X. et al. Fabrication of PANI-coated honeycomb-like MnO2 nanospheres with enhanced electrochemical performance for energy storage. Electrochim. Acta 180, 977–982 (2015).
Sun, M. et al. In situ growth of burl-like nickel cobalt sulfide on carbon fibers as high-performance supercapacitors. J. Mater. Chem. A 3, 1730–1736 (2015).
Zhou, J. et al. Importance of polypyrrole in constructing 3D hierarchical carbon nanotube@MnO2 perfect core–shell nanostructures for high-performance flexible supercapacitors. Nanoscale 7, 14697–14706 (2015).
Zhang, X., Ji, L., Zhang, S. & Yang, W. Synthesis of a novel polyaniline-intercalated layered manganese oxide nanocomposite as electrode material for electrochemical capacitor. J. Power Sources 173, 1017–1023 (2007).
Li, L. et al. Facile Synthesis of MnO2/CNTs composite for supercapacitor electrodes with long cycle stability. J. Phys. Chem. C 118, 22865–22872 (2014).
Liu, Z., Xu, K., Sun, H. & Yin, S. One-step synthesis of single-layer MnO2 nanosheets with multi-role sodium dodecyl sulfate for high-performance pseudocapacitors. Small 11, 2182–2191 (2015).
Liang, Y. et al. Direct access to metal or metal oxide nanocrystals integrated with one-dimensional nanoporous carbons for electrochemical energy storage. J. Am. Chem. Soc. 132, 15030–15037 (2010).
Rajagopal, R., Lee, Y. S. & Ryu, K.-S. Synthesis and electrochemical analysis of Nb2O5-TiO2/H-rGO sandwich type layered architecture electrode for supercapacitor application. Chem. Eng. J. 325, 611–623 (2017).
Mathis, T. S. et al. Energy storage data reporting in perspective—guidelines for interpreting the performance of electrochemical energy storage systems. Adv. Energy Mater. 9, 1902007 (2019).
Yeager, H. & Steck, A. Cation and water diffusion in Nafion ion exchange membranes: influence of polymer structure. J. Electrochem. Soc. 128, 1880 (1981).
Splith, T., Fröhlich, D., Henninger, S. K. & Stallmach, F. Development and application of an exchange model for anisotropic water diffusion in the microporous MOF aluminum fumarate. J. Magn. Reson. 291, 40–46 (2018).
This work was supported by the US National Science Foundation Division of Materials Research under Award number DMR-2002634 and the Office of Naval Research (ONR) under Award no. N00014-16-1-2921. The electrochemical measurement apparatus was purchased with the help of the US Air Force Office of Scientific Research (AFOSR) Grant No. FA9550-18-1-0020. C.N. thanks S. Buckler and D. Buckler for their generous support. J.C.R. and S.R.P. are supported by the US Department of Defense through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. V.A.P. is supported by the National Science Foundation Graduate Research Fellowship Program (NSF GRFP #2019279091). D.A.R. thanks the Columbia Nano Initiative for postdoctoral fellowship support. L.E.M. thanks Columbia University for lab startup funding. Y.Y. acknowledges support from the Air Force Office of Scientific Research (FA9550-20-1-0233).
The authors declare no competing interests.
Peer review information Nature Materials thanks Olivier Fontaine and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
a, Cyclized PHATN (2) and the thermolyzed product (PHATN). Note the retention of the characteristic aromatic material peaks between 𝛿 200-100 ppm and the disappearance of the alkyl peaks between 𝛿 75-0 ppm, indicating the near-quantitative removal of the alkyl chains during thermolysis. b, Solid-state 13C NMR of the PHATN material incorporated into an electrode (see Methods for details), both as-fabricated (orange trace) and soaked in electrolyte (purple trace), showing a shift assigned to ion association to a carbonyl within the material. Asterisks denote spinning sidebands at magic angle spinning frequency of 18 kHz.
(a) Top-view and (b) side-view of the DFT energy-minimized structure of Extended PHATN composed of multiple units of PDI and HATN. The accessible space provided by molecular contortion is clearly visible.
Extended Data Fig. 3 Specific capacitance as a function of current density for PHATN and a suite of benchmark materials.
Green symbols are carbon-based materials;35,49,50,51 red symbols are conducting polymer-based materials;5,27,31,32,33,34,52,53,54,55,56,57,58,59,60,61,62,63,64 purple symbols are hybrid organic/inorganic materials;65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82 and blue symbols are inorganic materials83,84,85,86,87,88,89,90,91,92. PHATN outperforms nearly all other pure organic materials at lower rates, and at higher rates achieves performance unprecedented in any material class besides inorganic compounds. PHATN values and all reference values are taken from three-electrode measurements.
Adsorption (filled symbols) and desorption (open symbols) isotherms of CO2 for PHATN (dark green) and PA-PDI (blue) collected at −78 °C. Analysis of the PHATN isotherm (dark green) shows a Brunauer-Emmett-Teller surface area of 131 m2/g, calculated using the pressure range 50–227 torr, and a Langmuir surface area of 671 m2/g, calculated using the pressure range of 227–647 torr. However, as PHATN can likely undergo further structural distortions under operating conditions, these values are intended to be an estimate of the surface area and are included here for reporting purposes only. Analysis of the PA-PDI isotherm (blue) shows a Brunauer-Emmett-Teller surface area of 12 m2/g, calculated using the pressure range 50–227 torr. This is indicative of extremely low porosity, consistent with our hypothesis that contortion is crucial to the characteristic porosity shown in PHATN.
a, High frequency region of the Nyquist plots displaying potential dependence of the diameter of the semicircular segment. The change in diameter of the semicircle with potential is indicative of a change in charge transfer resistance, as expected from a pseudocapacitive process93. The dotted lines are guides for the eye. b, Low frequency region of the Nyquist plots, which shows steeper Warburg regions at more negative potentials. c, Frequency dependence of the specific capacitance, which shows a low-frequency plateau forming near 800 F/g – near the maximum measured capacitance (689 F/g) and approaching the theoretical capacitance of the material (996 F/g). The potentials are in V vs Hg/HgO.
(a), (b), and (c) show the effect of holding the electrode at the max charge voltage before allowing to relax, with (a) in linear time, (b) in log time, and (c) in root time. (d), (e), and (f) show the effect of the max charge voltage on the self-discharge behavior, with (d) in linear time, (e) in log time, and (f) in root time.
a, CV of PA-PDI shows similar reversible redox peaks to PHATN, though sharper and less broad. b, GCD of PA-PDI shows relatively high IR drop and less ideal triangular capacitor shape. All measurements were performed in 6 M KOH aqueous electrolyte.
a, CV at 50 mV/s and b, GCD at 1 A/g. c, Nyquist plot of PA-PDI, when compared to PHATN, displays a less steep Warburg slope in the low-frequency region, indicating less capacitive character. Both measurements are performed at −0.7 V vs Hg/HgO. Frequency range is from 100 kHz to 20 mHz.
a, Specific capacitance values vs. rate for PHATN and PA-PDI. The latter has consistently lower performance, especially at high rates, attributable to the absence of contortion and resulting internal space which enable ion movement. b, Capacity retention and coulombic efficiency vs. number of cycles for PA-PDI. The material maintains the same high stability over 10,000 cycles as PHATN, indicating that the polymeric material is well-formed and not affected by repeated charging and discharging.
GITT discharge curves as function of time for (a) PHATN and (b) PA-PDI. The measurements were performed at 2 A/g with 20 s current pulse and 1 min open circuit relaxation. c, Schematic interpretation of the GITT data to estimate the diffusion constant (see below equation). d, Diffusion coefficient (D) of the charge carrying species measured from GITT for PHATN and PA-PDI. Comparing the diffusion coefficients across the potential range, we observe that the diffusion coefficient of PHATN (~1 × 10−7 cm2/s) is nearly one order of magnitude larger than that of PA-PDI (~3 × 10−8 cm2/s), indicating that the charge carrying species (K+) diffuses through the internal space created by contortion much more quickly, leading to the superior performance of PHATN. These values of ionic diffusion coefficients are comparable to reported values measured with aqueous electrolyte in porous polymeric materials94,95.
About this article
Cite this article
Russell, J.C., Posey, V.A., Gray, J. et al. High-performance organic pseudocapacitors via molecular contortion. Nat. Mater. 20, 1136–1141 (2021). https://doi.org/10.1038/s41563-021-00954-z