High-performance cerium oxide thin film electrodes prepared by layered deposition technique for enhanced supercapacitor performance

Abstract

This study focused on the synthesis of cerium oxide (CeO₂) electrodes using the Successive Ionic Layer Adsorption and Reaction (SILAR) method to enhance supercapacitor performance. The fabricated thin films exhibited a face-centered cubic structure of cerium oxide with a distinctive cauliflower-like nanostructure. This unique morphology increased the surface area, facilitated efficient ion diffusion, and significantly improved the electrochemical performance. The CeO₂ electrodes achieved a high specific capacitance of 659 F/g at a scan rate of 5 mV/s, as measured by cyclic voltammetry. The electrodes delivered a maximum energy density of 64 Wh/kg and a power density of 3499 W/kg. These results demonstrated that CeO₂ thin films are promising candidates for advanced supercapacitors and hold great potential for future energy storage applications.

Keywords

Electrode / Nanomaterial / CeO ₂ / Thin Film / SILAR / Supercapacitor

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Rushikesh G. Bobade: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft. Bidhan Pandit: Writing – review & editing, Supervision. Akhil P. Khedulkar: Writing – review & editing. Shoyebmohamad F. Shaikh: Writing – review & editing. Revanappa C. Ambare: Writing – review & editing, Supervision.

Acknowledgements

The authors extend their sincere appreciation to the Researchers Supporting Project No. RSP2025R370, King Saud University, Riyadh, Saudi Arabia. Dr. Bidhan Pandit acknowledges the Iberdrola Foundation and European Commission MSCA-E4F program (Horizon 2020, Grant No. 101034297) for support.

References

[1] R.G. Bobade, N.B. Dabke, S.F. Shaikh, B.J. Lokhande, R.S. Mane, R.C. Ambare, Facile chemical synthesis of BaO:MgO nanorods for designing distinctive solid-state asymmetric supercapacitor device with activated carbon, J. Energy Storage 84 (2024) 110776, doi: 10.1016/j.est.2024.110776.

[2] R.G. Bobade, N.B. Dabke, S.F. Shaikh, A.M. Al-Enizi, B. Pandit, B.J. Lokhande, R.C. Ambare, Influence of deposition potential on electrodeposited bismuth-copper oxide electrodes for asymmetric supercapacitor, Batter. Supercaps 7 (2024) e202400163, doi: 10.1002/batt.202400163.

[3] D.S. Gaikwad, R.G. Bobade, U.T. Nakate, P. Rosaiah, A.M. Tighezza, B.J. Lokhande, R.C. Ambare, SILAR-synthesized Co₃O₄/Bi₂O₃ on copper substrate nanocomposite electrode and asymmetric Co₃O₄/Bi₂O₃/CuO: AC solid-state device in supercapacitor , J. Mater. Sci. Mater. Electron. 35 (2024) 489, doi: 10.1007/s10854-024-12220-4.

[4] H.T. Das, E.B. T, S. Dutta, N. Das, P. Das, A. Mondal, M. Imran, Recent trend of CeO₂-based nanocomposites electrode in supercapacitor: A review on energy storage applications , J. Energy Storage 50 (2022) 104643, doi: 10.1016/j.est.2022.104643.

[5] Z.M. Riyas, M.R. Prabhu, Microwave irradiation effect of La₂O₃-CeO₂ nanocomposites as a potential electrode material for asymmetric supercapacitor , Ionics 30 (2024) 5737-5754, doi: 10.1007/s11581-024-05625-y.

[6] X. Wang, J. Wang, Y. Sun, K. Li, T. Shang, Y. Wan, Recent advances and perspectives of CeO₂-based catalysts: Electronic properties and applications for energy storage and conversion , Front. Chem. 10 (2022) 1089708, doi: 10.3389/fchem.2022.1089708.

[7] P. Salarizadeh, M.B. Askari, H. Beydaghi, M. Rastgoo-Deylami, S.M. Rozati, Hybrid of cerium dioxide nanoparticles/reduced graphene oxide as an electrode material for supercapacitor applications, J. Phys. Chem. Solids 159 (2021) 110284, doi: 10.1016/j.jpcs.2021.110284.

[8] S.K. Godlaveeti, S.K. Arla, A.M. Tawfeek, S. Sangaraju, S.W. Joo, A.R. Somala, Synthesis and electrochemical performance of CeO₂/NiS nanocomposite for enhanced asymmetric supercapacitor device applications , Mater. Sci. Semicond. Process. 184 (2024) 108796, doi: 10.1016/j.mssp.2024.108796.

[9] Y. Xu, Y. Zhou, Y. Li, Y. Liu, Z. Ding, Advances in cerium dioxide nanomaterials: Synthesis strategies, property modulation, and multifunctional applications, J. Environ. Chem. Eng. 12 (2024) 113719, doi: 10.1016/j.jece.2024.113719.

[10] S. Surendhiran, K.S. Balu, A. Karthik, V. Rajendran, Biogenic synthesis of CeO₂ nanoparticles via moringa oleifera seed extract: Photocatalytic and biological activity for textile dye degradation , J. Indian Chem. Soc. 101 (2024) 101302, doi: 10.1016/j.jics.2024.101302.

[11] A.J. Khan, M. Hanif, M.S. Javed, S. Hussain, W. Zhong, M. Saleem, Z. Liu, Energy storage properties of hydrothermally processed, nanostructured, porous CeO₂ nanoparticles , J. Electroanal. Chem. 865 (2020) 114158, doi: 10.1016/j.jelechem.2020.114158.

[12] A. Xie, H. Wang, Z. Zhu, W. Zhang, X. Li, Q. Wang, S. Luo, Mesoporous CeO₂- 𝛼-MnO₂-reduced graphene oxide composite with ultra-high stability as a novel electrode material for supercapacitor , Surf. Interfaces 25 (2021) 101177, doi: 10.1016/j.surfin.2021.101177.

[13] J. Huang, K. Yuan, Y. Chen, Wide voltage aqueous asymmetric supercapacitors: Advances, strategies, and challenges, Adv. Funct. Mater. 32 (2022) 2108107, doi: 10.1002/adfm.202108107.

[14] S. Sharma, P. Chand, Supercapacitor and electrochemical techniques: A brief review, Results Chem. 5 (2023) 100885, doi: 10.1016/j.rechem.2023.100885.

[15] M. Stefan, A.M. Rostas, A.U. Ammar, A. Güngör, E. Saritas, D. Toloman, A. Varadi, S. Macavei, L. Barbu-Tudoran, C. Leostean, O. Pana, A. Kasza, E. Erdem, A. Popa, Cerium enhanced supercapacitive properties of zinc oxide nanoflowers, Energy Fuels 38 (2024) 19088-19099, doi: 10.1021/acs.energyfuels.4c03091.

[16] L. Xie, F. Su, L. Xie, X. Guo, Z. Wang, Q. Kong, G. Sun, A. Ahmad, X. Li, Z. Yi, C. Chen, Effect of pore structure and doping species on charge storage mechanisms in porous carbon-based supercapacitors, Mater. Chem. Front. 4 (2020) 2610-2634, doi: 10.1039/d0qm00180e.

[17] K. Kowsuki, R. Nirmala, Y.H. Ra, R. Navamathavan, Recent advances in cerium oxide-based nanocomposites in synthesis, characterization, and energy storage applications: A comprehensive review, Results Chem 5 (2023) 100877, doi: 10.1016/j.rechem.2023.100877.

[18] A. Joseph, S. Perikkathra, T. Thomas, Novel 2D CeO₂ nanoflakes as a high-performance asymmetric supercapacitor electrode material , J. Energy Storage 68 (2023) 107757, doi: 10.1016/j.est.2023.107757.

[19] I.M. Nwachukwu, A.C. Nwanya, R. Osuji, F.I. Ezema, Nanostructured Mn-doped CeO₂ thin films with enhanced electrochemical properties for pseudocapacitive applications , J. Alloys Compd. 886 (2021) 161206, doi: 10.1016/j.jallcom.2021.161206.

[20] G. Veeresha, G. Krishnamurthy, M.S. Shivakumar, Cobalt nanocrystals doped on CeO₂/rGO nanocomposite for supercapacitor applications , Inorg. Chem. Commun. 138 (2022) 109232, doi: 10.1016/j.inoche.2022.109232.

[21] M. Nallappan, M. Gopalan, Fabrication of CeO₂/PANI composites for high energy density supercapacitors , Mater. Res. Bull. 106 (2018) 357-364, doi: 10.1016/j.materresbull.2018.05.025.

[22] Y. Luo, T. Yang, Q. Zhao, M. Zhang, CeO₂/CNTs hybrid with high performance as electrode materials for supercapacitor , J. Alloys Compd. 729 (2017) 64-70, doi: 10.1016/j.jallcom.2017.09.165.

[23] R. Anjana, P.M. Anjana, J. Alex, R. Isaac, R.S.S. Hussain, D. Sajan, Investigations on supercapacitor performance of novel ZnO-CeO₂-rGO nanohybrid prepared via hydrothermal method for energy storage applications and their charge storage mechanism , Diam. Relat. Mater. 146 (2024) 111241, doi: 10.1016/j.diamond.2024.111241.

[24] M. Sun, Z. Li, H. Li, Z. Wu, W. Shen, Y.Q. Fu, Mesoporous Zr-doped CeO₂ nanostructures as superior supercapacitor electrode with significantly enhanced specific capacity and excellent cycling stability , Electrochim. Acta 331 (2020) 135366, doi: 10.1016/j.electacta.2019.135366.

[25] G. Murugadoss, J. Ma, X. Ning, M.R. Kumar, Selective metal ions doped CeO₂ nanoparticles for excellent photocatalytic activity under sun light and supercapacitor application , Inorg. Chem. Commun. 109 (2019) 107577, doi: 10.1016/j.inoche.2019.107577.

[26] V.B. Suryawanshi, R.G. Bobade, D.S. Gaikwad, U.T. Nakate, S.F. Shaikh, B.J. Lokhande, R.C. Ambare, Nano-architectured BaO thin film electrode synthesized via SILAR technique for supercapacitor application, Chem. Pap. 78 (2024) 4689-4697, doi: 10.1007/s11696-024-03400-x.

[27] D.S. Gaikwad, R.G. Bobade, V.B. Suryawanshi, U.T. Nakate, S.F. Shaikh, A.M. Al-Enizi, N.B. Dabke, B.J. Lokhande, R.C. Ambare, Electrochemical property of nanosphere-like MgO electrode synthesized via SILAR in asymmetric supercapacitor, J. Mater. Sci. Mater. Electron. 35 (2024) 363, doi: 10.1007/s10854-024-12196-1.

[28] V. Vishnu Narayanan, B.S. Jagannathan, K.S. Rajni, SILAR deposited Cu₂MnSnS₄ thin films for sustainable energy applications , Mater. Lett. 359 (2024) 135875, doi: 10.1016/j.matlet.2024.135875.

[29] P.P. Bagwade, D.B. Malavekar, S.B. Ubale, R.N. Bulakhe, I. In, U.M. Patil, C.D. Lokhande, Synthesis, characterization and supercapacitive application of nanocauliflower-like cobalt tungstate thin films by successive ionic layer adsorption and reaction (SILAR) method, Electrochim. Acta 408 (2022) 139933, doi: 10.1016/j.electacta.2022.139933.

[30] A. Raza, A. Farid, A. Rasheed, M. Yousaf, I.A. Khan, K.M.H. Mohammed, M.A. Ghanem, Home-made chemical vapor deposition-based synthesis of binder-free nanostructured magnesium-molybdenum-sulfide electrode materials for supercapacitor application, J. Phys. Chem. Solids 192 (2024) 112093, doi: 10.1016/j.jpcs.2024.112093.

[31] L. Tan, J. Zhou, X. Zhao, S. Wang, M. Li, C. Jiang, H. Li, Y. Zhang, Y. Ye, W. Tress, L. Ding, M. Grätzel, C. Yi, Combined vacuum evaporation and solution process for high-efficiency large-area perovskite solar cells with exceptional reproducibility, Adv. Mater. 35 (2023) 2205027, doi: 10.1002/adma.202205027.

[32] S.S. Pujari, R.G. Bobade, S.F. Shaikh, A.M. Al-Enizi, R.C. Ambare, B.J. Lokhande, A binderless Ru: 𝛼-Fe₂O₃ binary nanocomposite electrode for supercapacitor applications , J. Mater. Sci. Mater. Electron. 35 (2024) 2162, doi: 10.1007/s10854-024-13857-x.

[33] S.S. Pujari, R.G. Bobade, R.C. Ambare, B.J. Lokhande, Temperature-contingent electrochemical capacitive concert of nanospheres Fe₂O₃ as a supercapacitor electrode , ES Chem. Sustain. 1 (2024) 1323, doi: 10.30919/escs1323.

[34] S.S. Pujari, R.G. Bobade, R.C. Ambare, B.J. Lokhande, Facile fabrication of binary mixed phase Ru doped Fe₂O₃ as a potential electrode material for high-performance supercapacitors , ES Energy Environ. 27 (2024) 1324, doi: 10.30919/esee1324.

[35] D.B. Malavekar, R.N. Bulakhe, S.B. Kale, U.M. Patil, I. In, C.D. Lokhande, Synthesis of layered copper selenide on reduced graphene oxide sheets via SILAR method for flexible asymmetric solid-state supercapacitor, J. Alloys Compd. 869 (2021) 159198, doi: 10.1016/j.jallcom.2021.159198.

[36] T.M. Nejkar, N.R. Mulla, U.M. Patil, D.P. Dubal, R.S. Patil, SILAR synthesized 𝛼-Fe₂O₃ thin film anode for the development of all binder-free, high-performing Mg-ion asymmetric supercapacitors , J. Energy Storage 99 (2024) 113443, doi: 10.1016/j.est.2024.113443.

[37] N.C. Maile, S.K. Shinde, K.S. Patil, A.V. Fulari, A. Shahzad, D.S. Lee, V.J. Fulari, Capacitive property studies of inexpensive SILAR synthesized polyaniline thin films for supercapacitor application, SN Appl. Sci. 1 (2019) 1333, doi: 10.1007/s42452-019-1403-6.

[38] D.P.M.D. Shaik, P. Rosaiah, O.M. Hussain, Fabrication of the Mn₃O₄ thin film electrodes by electron beam evaporation for supercapacitor applications , J. Electroanal. Chem. 851 (2019) 113409, doi: 10.1016/j.jelechem.2019.113409.

[39] L. Li, W. Liu, H. Dong, Q. Gui, Z. Hu, Y. Li, J. Liu, Surface and interface engineering of nanoarrays toward advanced electrodes and electrochemical energy storage devices, Adv. Mater. 33 (2021) 2004959, doi: 10.1002/adma.202004959.

[40] M. Kim, J. Ha, Y.T. Kim, J. Choi, Stainless steel: A high potential material for green electrochemical energy storage and conversion, Chem. Eng. J. 440 (2022) 135459, doi: 10.1016/j.cej.2022.135459.

[41] M. Salve, A. Mandal, K. Amreen, P.K. Pattnaik, S. Goel, Greenly synthesized silver nanoparticles for supercapacitor and electrochemical sensing applications in a 3D printed microfluidic platform, Microchem. J. 157 (2020) 104973, doi: 10.1016/j.microc.2020.104973.

[42] M.A. Desai, A. Kulkarni, G. Gund, S.D. Sartale, SILAR grown K⁺ and Na⁺ ions preinserted MnO₂ nanostructures for supercapacitor applications: A comparative study , Energy Fuels 35 (2021) 4577-4586, doi: 10.1021/acs.energyfuels.0c04252.

[43] R.G. Bobade, B. Pandit, A.P. Khedulkar, V.S. Raykar, P.B. Sarawade, S.F. Shaikh, C. Huang, R.C. Ambare, Electrochemical investigation of crinum asiaticum-like BaO-CeO₂ nanostructure for high-performance asymmetric supercapacitor , Inorg. Chem. Commun. 177 (2025) 114370, doi: 10.1016/j.inoche.2025.114370.

[44] S.P. Ratnayake, J. Ren, E. Colusso, M. Guglielmi, A. Martucci, E.Della Gaspera, SILAR deposition of metal oxide nanostructured films, Small 17 (2021) 2101666, doi: 10.1002/smll.202101666.

[45] H. Soonmin, Recent advances in the growth and characterizations of SILAR-deposited thin films, Appl. Sci. 12 (2022) 8184, doi: 10.3390/app12168184.

[46] S. Yang, L. Zhang, C. Shao, X. Li, X. Li, S. Liu, R. Tao, Y. Liu, Facile preparation of flexible polyacrylonitrile/BiOCl/BiOI nanofibers via SILAR method for effective floating photocatalysis, J. Sol-Gel Sci. Technol. 97 (2021) 610-621, doi: 10.1007/s10971-020-05453-2.

[47] M. Jayashree, V. Sharmila, K.L. Meganathan, R. BoopathiRaja, M. Parthibavarman, M. Shkir, S. AlFaify, Design and fabrication of graphene anchored CeO₂ hybrid nanocomposite electrodes for high performance energy storage device applications , Inorg. Chem. Commun. 132 (2021) 108838, doi: 10.1016/j.inoche.2021.108838.

[48] P. Shanmugam, G.P. Kuppuswamy, K. Pushparaj, B. Arumugam, A. Sundaramurthy, Y. Sivalingam, CeO₂ nanoparticles based extended gate field effect transistor for enzyme free detection of glucose , J. Mater. Sci. Mater. Electron. 33 (2022) 9483-9489, doi: 10.1007/s10854-021-07441-w.

[49] A. Pandiyan, R. Rajagopalan, W.H. Tanveer, W. Yu, S.W. Cha, S.B. Krishna Moorthy, Scalable lattice-strain in preferentially oriented acceptor-doped cerium oxide film and its impact on oxygen ion transport kinetics, Electrochim. Acta 264 (2018) 203-215, doi: 10.1016/j.electacta.2018.01.097.

[50] V. Kumar, W.F. Chen, X. Zhang, Y. Jiang, P. Koshy, C.C. Sorrell, Properties and performance of photocatalytic CeO₂, TiO₂, and CeO₂-TiO₂ layered thin films , Ceram. Int. 45 (2019) 22085-22094, doi: 10.1016/j.ceramint.2019.07.225.

[51] T. Kaur, K. Singh, J. Kolte, Effect of intrinsic and extrinsic oxygen vacancies on the conductivity of Gd-doped CeO₂ synthesized by a sonochemical route , J. Phys. Chem. C 126 (2022) 18018-18028, doi: 10.1021/acs.jpcc.2c04851.

[52] A. Jeyaranjan, T.S. Sakthivel, C.J. Neal, S. Seal, Scalable ternary hierarchical microspheres composed of PANI/rGO/CeO₂ for high performance supercapacitor applications , Carbon 151 (2019) 192-202, doi: 10.1016/j.carbon.2019.05.043.

[53] R.G. Bobade, N.B. Dabke, S.F. Shaikh, A.M. Al-Enizi, B. Pandit, B.J. Lokhande, R.C. Ambare, Concentration-dependent SILAR synthesized di-bismuth copper oxide nano-materials electrode in asymmetric supercapacitor, J. Mater. Sci. Mater. Electron. 35 (2024) 129, doi: 10.1007/s10854-023-11818-4.

[54] I.W. Sutapa, A.Wahid Wahab, P. Taba, N.L. Nafie, Dislocation, crystallite size distribution and lattice strain of magnesium oxide nanoparticles, J. Phys. Conf. Ser. 979 (2018) 012021, doi: 10.1088/1742-6596/979/1/012021.

[55] S. Veziroglu, K. Röder, O. Gronenberg, A. Vahl, O. Polonskyi, T. Strunskus, H.G. Rubahn, L. Kienle, J. Adam, J. Fiutowski, F. Faupel, O.C. Aktas, Cauliflower-like CeO₂-TiO₂ hybrid nanostructures with extreme photocatalytic and self-cleaning properties , Nanoscale 11 (2019) 9840-9844, doi: 10.1039/C9NR01208G.

[56] N. Chakrabarty, A. Dey, S. Krishnamurthy, A.K. Chakraborty, CeO₂/Ce₂O₃ quantum dot decorated reduced graphene oxide nanohybrid as electrode for supercapacitor , Appl. Surf. Sci. 536 (2021) 147960, doi: 10.1016/j.apsusc.2020.147960.

[57] P. Bhojane, Recent advances and fundamentals of pseudocapacitors: Materials, mechanism, and its understanding, J. Energy Storage 45 (2022) 103654, doi: 10.1016/j.est.2021.103654.

[58] S. Asaithambi, P. Sakthivel, M. Karuppaiah, R. Yuvakkumar, K. Balamurugan, T. Ahamad, M.A.M. Khan, G. Ramalingam, M.K.A. Mohammed, G. Ravi, Preparation of Fe-SnO₂@CeO₂ nanocomposite electrode for asymmetric supercapacitor device performance analysis , J. Energy Storage 36 (2021) 102402, doi: 10.1016/j.est.2021.102402.

[59] S.D. Jituri, S.M. Nikam, T.S. Bane, A.I. Inamdar, S.H. Mujawar, Porous cauliflower-like nanoarchitectures of NiMn-layered double hydroxide as a promising electrode for oxygen evolution reaction and supercapacitor applications, Electrochim. Acta 513 (2025) 145544, doi: 10.1016/j.electacta.2024.145544.

[60] N. Padmanathan, S. Selladurai, Shape controlled synthesis of CeO₂ nanostructures for high performance supercapacitor electrodes , RSC Adv. 4 (2014) 6527-6534, doi: 10.1039/c3ra43339k.

[61] T.A. Sandosh, A. Simi, Morphology controlled synthesis of one-dimensional CoMn₂O₄ nanorods for high-performance supercapacitor electrode application , Chem. Pap. 75 (2021) 2295-2304, doi: 10.1007/s11696-020-01448-z.

[62] G. Harichandran, S. Radha, P. Divya, J. Yesuraj, Facile morphology-controlled synthesis of nanostructured MnMoO₄ nanorods as an advance electrode material for supercapacitor application , J. Mater. Sci. Mater. Electron. 31 (2020) 1646-1653, doi: 10.1007/s10854-019-02681-3.

[63] N. Tiwari, S.L. Kadam, R.S. Ingole, R.K. Kamat, S. Kulkarni, Novel synthesis of cauliflower-like nanostructured ZnFe₂O₄ high-performance electrode for supercapattery applications , Int. J. Green Energy 21 (2024) 919-928, doi: 10.1080/15435075.2023.2224441.

[64] S.H.S. Pai, S.K. Pandey, E.J.J. Samuel, J.U. Jang, A.K. Nayak, H.S. Han, Recent advances in NiO-based nanostructures for energy storage device applications, J. Energy Storage 76 (2024) 109731, doi: 10.1016/j.est.2023.109731.

[65] Y. Liu, S.P. Jiang, Z. Shao, Intercalation pseudocapacitance in electrochemical energy storage: Recent advances in fundamental understanding and materials development, Mater. Today Adv. 7 (2020) 100072, doi: 10.1016/j.mtadv.2020.100072.

[66] Z. Wang, R. Yu, Hollow micro/nanostructured ceria-based materials: Synthetic strategies and versatile applications, Adv. Mater. 31 (2019) 1800592, doi: 10.1002/adma.201800592.

[67] S. Sultana, S. Mansingh, K.M. Parida, Crystal facet and surface defect engineered low dimensional CeO₂ (0D, 1D, 2D) based photocatalytic materials towards energy generation and pollution abatement , Mater. Adv. 2 (2021) 6942-6983, doi: 10.1039/d1ma00539a.

[68] Y. Zhang, J. Deng, M. Luo, T. Pang, P. Shi, F. Li, Cauliflower-like CoNi₂S₄ microspheres derived from bimetallic hydroxides as highly active electrode material for asymmetric supercapacitors , J. Mater. Sci. Mater. Electron. 35 (2024) 2082, doi: 10.1007/s10854-024-13859-9.

[69] N. Maheswari, G. Muralidharan, Ag-incorporated CeO₂ nano cauliflowers for high-performance supercapacitor devices , New J. Chem. 41 (2017) 10841-10850, doi: 10.1039/c7nj00817a.

[70] K. Yang, S. Cheng, Z. Yao, S. Li, Y. Yang, Dumbbell shaped nanocomposite Co₃O₄/CeO₂ derived from metal-organic frameworks (MOFs) as an excellent non-enzymatic glucose sensor , Solid State Sci 150 (2024) 107498, doi: 10.1016/j.solidstatesciences.2024.107498.

[71] B.E. Conway, W.G. Pell, Power limitations of supercapacitor operation associated with resistance and capacitance distribution in porous electrode devices, J. Power Sources 105 (2002) 169-181, doi: 10.1016/S0378-7753(01)00936-3.

[72] M.Y. Perdana, B.A. Johan, M. Abdallah, M.E. Hossain, M.A. Aziz, T.N. Baroud, Q.A. Drmosh, Understanding the behavior of supercapacitor materials via electrochemical impedance spectroscopy: A review, Chem. Rec. 24 (2024) e202400007, doi: 10.1002/tcr.202400007.

[73] K. Panigrahi, S. Mal, S. Bhattacharyya, Deciphering interfacial charge transfer mechanisms in electrochemical energy systems through impedance spectroscopy, J. Mater. Chem. A 12 (2024) 14334-14353, doi: 10.1039/D4TA00537F.

[74] A.A. Moya, Low-frequency development approximations to the transmissive Warburg diffusion impedance, J. Energy Storage 55 (2022) 105632, doi: 10.1016/j.est.2022.105632.

[75] Z. Xu, Y. Li, S. Li, Y. Chen, M. Farahmandjou, G. Wang, H. Yang, H. Tian, A general strategy for the in situ construction of CoSe₂-MSe_x@GA (M = Zn, Ni, and Fe) heterostructures for effective sodium storage , Inorg. Chem. Front. 11 (2024) 8078-8092, doi: 10.1039/D4QI01704H.

[76] Z. Xiong, H. Shi, W. Zhang, J. Yan, J. Wu, C. Wang, D. Wang, J. Wang, Y. Gu, F. Chen, Y. Yang, B. Xu, X. Yan, In situ growth of iron sulfide on fast charge transfer V₂C-MXene for superior sodium storage anodes , Small 19 (2023) 2206767, doi: 10.1002/smll.202206767.

[77] R. Tatara, P. Karayaylali, Y. Yu, Y. Zhang, L. Giordano, F. Maglia, R. Jung, J.P. Schmidt, I. Lund, Y. Shao-Horn, The effect of electrode-electrolyte interface on the electrochemical impedance spectra for positive electrode in Li-ion battery, J. Electrochem. Soc. 166 (2019) A5090-A5098, doi: 10.1149/2.0121903jes.

[78] M.A. Zabara, G. Katırcı, F.E. Civan, A. Yürüm, S.A. Gürsel, B. Ülgüt, Insights into charge transfer dynamics of Li batteries through temperature-dependent electrochemical impedance spectroscopy (EIS) utilizing symmetric cell configuration, Electrochim. Acta 485 (2024) 144080, doi: 10.1016/j.electacta.2024.144080.

[79] N. Afza, M.S. Shivakumar, G. Krishnamurthy, M. Mylarappa, C.R. Ravikumar, Ni-doped cerium oxide on rGO: A hydrothermal approach for high-performance supercapacitors, Sustain. Chem. Environ. 6 (2024) 100117, doi: 10.1016/j.scenv.2024.100117.

[80] Q. He, W. Wang, G. Li, W. Chen, X. Yang, C. Ni, X. Fang, Urchin-like Ce(HCOO)₃ synthesized by a microwave-assisted method and its application in an asymmetric supercapacitor , Molecules 29 (2024) 420, doi: 10.3390/molecules29020420.

[81] T. Zhou, W. Zhang, H. Fu, J. Fang, C. Chen, Z. Wang, Preparation of 3D CeO₂@NiFe-LDH composites derived from Prussian blue analogues for high performance supercapacitors , Mater. Sci. Semicond. Process. 150 (2022) 106913, doi: 10.1016/j.mssp.2022.106913.

[82] P. Mehra, C. Singh, I. Cherian, A. Giri, A. Paul, Deciphering the incredible supercapacitor performance of conducting biordered ultramicroporous graphitic carbon, ACS Appl. Energy Mater. 4 (2021) 4416-4427, doi: 10.1021/acsaem.1c00020.

[83] H. Yang, B. Chen, Z. Guo, H. Liu, Y. Zhang, H. Huang, R. Xu, R. Fu, Effects of current density on preparation and performance of Al/conductive coating/a-PbO₂-CeO₂-TiO₂/ß-PbO₂-MnO₂-WC-ZrO₂ composite electrode materials , Trans. Nonferrous Met. Soc. China 24 (2014) 3394-3404, doi: 10.1016/S1003-6326(14)63482-8.

[84] S. Karmakar, S. Varma, D. Behera, Investigation of structural and electrical transport properties of nano-flower shaped NiCo₂O₄ supercapacitor electrode materials , J. Alloys Compd. 757 (2018) 49-59, doi: 10.1016/j.jallcom.2018.05.056.

[85] S. Ahmad, S.I.A. Shah, A. Naz, M. Rafeeq, R.A. Alshgari, M.F. Ehsan, S. Mohammad, M.N. Ashiq, Study on effect of surface engineering by In doped CeCu₂O₄ for enhanced super capacitive properties as energy storage solution , J. Energy Storage 86 (2024) 111406, doi: 10.1016/j.est.2024.111406.

[86] A. Manohar, G.R. Reddy, N. Roy, M. Ubaidullah, A.A. Al-Kahtani, M. Gupta, K.H. Kim, Comprehensive characterization of a Mn_0.1Mg_0.9Fe₂O₄/CeO₂/MgFe₂O₄ nanocomposite for high-performance supercapacitor applications , Ceram. Int. 50 (2024) 10436-10445, doi: 10.1016/j.ceramint.2023.12.356.

[87] S. Arunpandiyan, S. Vinoth, A. Pandikumar, A. Raja, A. Arivarasan, Decoration of CeO₂ nanoparticles on hierarchically porous MnO₂ nanorods and enhancement of supercapacitor performance by redox additive electrolyte , J. Alloys Compd. 861 (2021) 158456, doi: 10.1016/j.jallcom.2020.158456.

[88] C. Tang, X. Wang, M. Ma, Z. Wang, Y. Li, H. Li, B. Li, Y. Zhang, X. Zhu, Optimizing the electrons/ions diffusion kinetics in 𝛿-MnO₂ for realizing an ultra-high rate-capability supercapacitor , Chem. Eng. J. 471 (2023) 144784, doi: 10.1016/j.cej.2023.144784.

[89] L. Mai, H. Li, Y. Zhao, L. Xu, X. Xu, Y. Luo, Z. Zhang, W. Ke, C. Niu, Q. Zhang, Fast ionic diffusion-enabled nanoflake electrode by spontaneous electrochemical pre-intercalation for high-performance supercapacitor, Sci. Rep. 3 (2013) 1718, doi: 10.1038/srep01718.

[90] W. Li, Q.A. Huang, Y. Bai, J. Wang, L. Wang, Y. Liu, Y. Zhao, X. Li, J. Zhang, Model reduction of fractional impedance spectra for time-frequency analysis of batteries, fuel cells, and supercapacitors, Carbon Energy 6 (2024) e360, doi: 10.1002/cey2.360.

[91] R.G. Bobade, A.P. Khedulkar, R.S. Ingole, V.B. Suryawanshi, S.F. Shaikh, R.C. Ambare, Development of flake-rod like SrO thin films via SILAR method for efficient energy storage in supercapacitors, J. Mater. Sci. Mater. Electron. 36 (2025) 408, doi: 10.1007/s10854-025-14330-z.

[92] A. Shokry, M. Karim, M. Khalil, S. Ebrahim, J. El Nady, Supercapacitor based on polymeric binary composite of polythiophene and single-walled carbon nanotubes, Sci. Rep. 12 (2022) 11278, doi: 10.1038/s41598-022-15477-z.

[93] D. Ohayon, G. Quek, B.R.P. Yip, F. Lopez-Garcia, P.R. Ng, R.J. Vázquez, D.V. Andreeva, X. Wang, G.C. Bazan, High-performance aqueous supercapacitors based on a self-doped n-type conducting polymer, Adv. Mater. 36 (2024) 2410512, doi: 10.1002/adma.202410512.

[94] B. Pandit, E.S. Goda, M.H. Abu Elella, A. ur Rehman, S.Eun Hong, S.R. Rondiya, P. Barkataki, S.F. Shaikh, A.M. Al-Enizi, S.M. El-Bahy, K.Ro Yoon, One-pot hydrothermal preparation of hierarchical manganese oxide nanorods for high-performance symmetric supercapacitors, J. Energy Chem. 65 (2022) 116-126, doi: 10.1016/j.jechem.2021.05.028.