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Nature volume 624, pages 74–79 (2023 )Cite this article Ultra Capacitor Car Audio
Electrochemical capacitors are expected to replace conventional electrolytic capacitors in line filtering for integrated circuits and portable electronics1,2,3,4,5,6,7,8. However, practical implementation of electrochemical capacitors into line-filtering circuits has not yet been achieved owing to the difficulty in synergistic accomplishment of fast responses, high specific capacitance, miniaturization and circuit-compatible integration1,4,5,9,10,11,12. Here we propose an electric-field enhancement strategy to promote frequency characteristics and capacitance simultaneously. By downscaling the channel width with femtosecond-laser scribing, a miniaturized narrow-channel in-plane electrochemical capacitor shows drastically reduced ionic resistances within both the electrode material and the electrolyte, leading to an ultralow series resistance of 39 mΩ cm2 at 120 Hz. As a consequence, an ultrahigh areal capacitance of up to 5.2 mF cm−2 is achieved with a phase angle of −80° at 120 Hz, twice as large as one of the highest reported previously4,13,14, and little degradation is observed over 1,000,000 cycles. Scalable integration of this electrochemical capacitor into microcircuitry shows a high integration density of 80 cells cm−2 and on-demand customization of capacitance and voltage. In light of excellent filtering performances and circuit compatibility, this work presents an important step of line-filtering electrochemical capacitors towards practical applications in integrated circuits and flexible electronics.
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We acknowledge the financial support from the National Science Foundation of China (grant nos. 22035005, 52022051, 52090032, 22075165 and 52073159), State Key Laboratory of Tribology in Advanced Equipment (SKLT) (SKLT2021B03) and the Tsinghua-Foshan Innovation Special Fund (2020THFS0501). F.L. acknowledges support from the National Natural Science Foundation of China (grant nos. 11972349 and 11790292) and the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB22040503). M.W. acknowledges the financial support from the National Science Foundation of China (grant no. 22105040), the Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China (grant no. 2021ZZ127) and the Natural Science Foundation of Fujian Province of China (grant no. 2021J01588). We also thank Z. Yu and X. Li from Peking University for their instruction in femtosecond-laser scribing technology and thank B. Yang from the North China Electric Power University for his instruction in constructing the line-filtering circuits.
These authors contributed equally: Yajie Hu, Mingmao Wu
Key Laboratory of Organic Optoelectronics and Molecular Engineering, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, People’s Republic of China
Yajie Hu, Fengyao Chi, Puying Li, Wenya He, Bing Lu, Chuanxin Weng, Fengen Chen, Huhu Cheng & Liangti Qu
Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, People’s Republic of China
Yajie Hu, Fengyao Chi, Puying Li, Wenya He, Bing Lu, Chuanxin Weng, Fengen Chen, Huhu Cheng & Liangti Qu
Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou, People’s Republic of China
Mingmao Wu & Guobin Lai
The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, People’s Republic of China
Guobin Lai, Jinguo Lin & Feng Liu
Laser Micro-/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, People’s Republic of China
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L.Q. supervised the entire project. Y.H., M.W. and L.Q. designed the experiments. Y.H. performed most of the experimental measurements with help from M.W., F. Chi, P.L., W.H., B.L., C.W., F. Chen and H.C. L.J. gave advice on experiments. Y.H., J.L., G.L. and F.L. conducted theoretical simulation. Y.H. prepared the paper with advice from M.W., F.L. and L.Q. All authors discussed the results and reviewed the paper.
The authors declare no competing interests.
Nature thanks the anonymous reviewers for their contribution to the peer review of this work.
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a–c, The schematic diagrams of designing strategies in general ECs (a), conventional line-filtering ECs (b), and NCECs (c). The subsequence numbers i and ii refer to the schematic diagrams of structural design and the corresponding typical Nyquist diagram, separately. Please see Supplementary Note 1 for the detailed explanation.
a, High-resolution TEM image of the graphene sheet. b,c, SEM images of as-fabricated VG array, concerning the lateral view (b) and the top view (c). d, Three-dimensional (3D) white-light interference (WLI) morphological graph of the VG array. e, Contact angles to PEDOT:PSS solution droplet for the Au current collector with VG array (left panel) and without VG array (right panel). f, SEM image of VG/PEDOT:PSS film from the top view. g, 3D WLI morphological graph of the VG/PEDOT:PSS film. h, The corresponding detailed thickness information derived by 3D WLI morphological graph in g.
a,b, HAADF-TEM images of PEDOT:PSS film (a) and PEDOT film (b). c, S (2p) X-ray photoelectron spectroscopy of PEDOT:PSS film and PEDOT film. After methanol treatment, the ratio of S (PSS) to S (PEDOT) changes from 2.18 to 1.52, indicating the decrease of PSS content. d, Nyquist diagram of PEDOT:PSS film and VG/PEDOT film. The ascending slope indicates the reduced transmission-line-like behaviour in PEDOT, which results from the enriched mesoporous structure. e, Raman spectrum of PEDOT film and VG/PEDOT film. f, Conductivity of PEDOT:PSS film, PEDOT film and VG/PEDOT film (n = 3; error bars indicate standard deviation).
a, Schematic diagram of the fabrication process of NCEC. b–d, SEM images of as-fabricated NCEC including, the lateral vision of VG/PEDOT film consisting of VG array and PEDOT parts (b), the top view of the fs-laser scribed channel (c), and the top view of the interdigital electrodes of NCEC. e, Comparison of SR and electrode interspacing between NCEC with other in-plane7,12,24,25,47,48,49,50,51,52 and sandwich-type1,4,5,8,13,14,22,23,53,54,55,56,57,58,59 line-filtering ECs. The number of the points is the reference number. f, Comparison of areal capacitance and phase angle at 120 Hz between NCECs with other in-plane49,50,51,60 and sandwich-type4,5,6,8,13,14,17,23,55,56,57,59,61,62 line-filtering ECs. The number of the points is the reference number.
a, The simulated kinetic process of ionic migration in NCECs in half a period: from state 1 that all the ions are stored in the left-side electrode (left panel) to state 3 that all the ions are stored in the right-side electrode (right panel). b, The stepwise evolution of ionic distribution of the NCEC with channel width of 5 μm (left panel) and 40 μm (right panel) from state 1 to state 3. c, The calculated φ of NCECs with different channel width. d, The calculated CA of NCECs with different channel width.
a, Schematic diagram of the experimental apparatus. b, Optical microscopic image of the experimental apparatus. c, Optical microscopic images of the tested NCECs with channel width of 5 μm, 20 μm and 40 μm. d, The cyclic voltammetry of the tested NCECs with channel width of 5 μm, 20 μm and 40 μm. e, The built-in voltage signal of the tested NCECs with channel width of 5 μm, 20 μm and 40 μm, varying with external voltage.
a, Scribing specified patterns and channels by fs-laser b, The as-prepared interdigital electrodes array. c, Scribing grate by laser. d, The as-prepared grate. e, Attachment of the grate onto interdigital electrodes array. f, Addition of electrolyte. g, Attachment of the top sealing cap. h, The as-prepared INM.
a, Optical microscopic image of 6×6 INM. b, Bode diagram of a single NCEC and 6×6 INM. c, Plots of real and imaginary part of capacitance versus frequency of a single NCEC and 6×6 INM. d, Cyclic voltammetry of 6×6 INM at different scan rates ranging from 1 V s−1 to 1,000 V s−1. e, Plot of the logarithm of anodic and cathodic currents (i) versus the logarithm of scan rates (v) for 6×6 INM. The b value is determined from the slope of the plots. f, GCD curves of 6×6 INM at different current ranging from 0.5 mA to 10 mA. g–l, Heat map showing electrochemical performances of each NCEC unit in 6×6 INM, including SR at 120 Hz (g), Rb (h), Rm at 120 Hz (i), thickness of VG/PEDOT (j), CA at 120 Hz (k), and relaxation time (l). m, Long-term stability test of 6×6 INM over 200,000 cycles.
a, Schematic circuit diagram of the switching circuit. b, Oscillograms of voltage signals filtered by aluminium ELCs which have the same capacitance as a single NCEC at 120 Hz (upper panel) and 1,000 Hz (bottom panel). c, Oscillograms of signals filtered by aluminium ELCs which have the same capacitance as 2×10 INM at 120 Hz (upper panel) and 1,000 Hz (bottom panel). d, Optical image of 2×10 INM. e, Plots of real and imaginary part of capacitance versus frequency of a single NCEC and 2×10 INM. f, Bode diagram of a single NCEC and 2×10 INM. g, Cyclic voltammetry of 2×10 INM at different scan rates ranging from 1 V s−1 to 500 V s−1.
a, Schematic circuit diagram of the flexible stroboscopic circuit. b, Optical image of the flexible PCB. c, Optical image of 3×3 INM. d, Bode diagram of a single NCEC and 3×3 INM. e, Plots of real and imaginary part of capacitance versus frequency of a single NCEC and 3×3 INM. f–i, Heat map showing electrochemical performances of each NCEC unit in 3×3 INM, including SR at 120 Hz (f), CA at 120 Hz (g), φ at 120 Hz (h), and partial voltage (i). j, φ and CA at 120 Hz of a single NCEC at different curvatures. Insets are the schematic diagram for the bending deformation of a single NCEC. k, Long-term stability test of a single NCEC at curvature of 2 cm−1 over 200,000 cycles.
This file contains Supplementary Figs. 1–8, Supplementary Note 1, Supplementary Tables 1–5 and Supplementary References.
This video shows the fluorescence tracing of the ionic migration in the NCECs for different channel widths.
This video shows the flexible stroboscopic circuit with the NCECs (3 × 3) integrated within.
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Hu, Y., Wu, M., Chi, F. et al. Ultralow-resistance electrochemical capacitor for integrable line filtering. Nature 624, 74–79 (2023). https://doi.org/10.1038/s41586-023-06712-2
DOI: https://doi.org/10.1038/s41586-023-06712-2
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