Viswanathan, A.Nityananda Shetty, A.N.2026-02-042024Electrochimica Acta, 2024, 477, , pp. -134686https://doi.org/10.1016/j.electacta.2024.143764https://idr.nitk.ac.in/handle/123456789/21278The driving force behind supercapacitor research is to enhance the energy density (E) to the level of Li-ion batteries, and achieving high power density (P). This task is accomplished by using nanocomposites of polyaniline (PANI) and Ni(OH)<inf>2</inf> (PN) as the electrode material for supercapacitors. These nanocomposites were synthesized using acetic acid (PN - AA) (PANI 75% and Ni(OH)<inf>2</inf> 25%) and methane sulphonic acid (PN - MSA) (PANI 83.33% and Ni(OH)<inf>2</inf> 16.67%) as dopants for PANI through an in-situ single-step method. The PN – MSA exhibited higher energy storage characters than PN – AA with 1 M H<inf>2</inf>SO<inf>4</inf> (SA) as electrolyte. PN - MSA exhibited high-energy characteristics, including a specific capacitance (C<inf>s</inf>) of 735.29 F g‒1, an energy density (E) of 147.05 W h kg‒1 (comparable to Li-ion batteries), and a power density (P) of 2.3466 kW kg‒1 at 1 A g‒1. In addition, it also exhibited an exceptional cyclic stability up to 58,800 cycles at 0.4 V s‒1. The energy characters of PN-AA are also substantially high and are a C<inf>s</inf> of 641.02 F g‒1, an E of 128.20 W h kg‒1 (in the same order of Li-ion batteries), a P of 2.0385 kW kg‒1 at 1 A g‒1 and a cyclic stability up to 18,400 cycles was also obtained at 0.4 V s‒1. Both PN - AA and PN - MSA demonstrated an impressive feature of an increase in energy storage with an increase in the number of charge/discharge cycles. PN - MSA exhibited an improvement in energy storage characteristics of up to 44% when a mixture of sulphuric acid and methane sulphonic acid with concentrations of 1 M and 0.33 M, respectively, was used as an electrolyte. © 2024 Elsevier LtdElectrolytesEnergy storageIonsLithium-ion batteriesMethaneNanocompositesNickel compoundsOrganic acidsPolyanilineStorage (materials)Acid mixture electrolyteAcid mixturesCyclic stabilityDriving forcesEnergyEnergy densityHigh-power-densityMethanesulphonic acidSulphuric acidSupporting electrolyteSupercapacitor