The energy transition and the intermittent characteristic of renewable energy sources highlight the importance of materials research for energy storage systems. Hexacyanometalates (HCM) are promising candidates in energy storage systems due to their structure, capability of intercalating/extracting ions during the redox process, and the variety of synthesis techniques available. Among HCMs, nickel hexacyanoferrate (NiHCF) gains attention due to its long-life cycle and promising application in aqueous systems. Combining the properties of NiHCF along with freestanding films based on reduced graphene oxide (rGO) and polyaniline (PAni) offers a promising application in aqueous batteries as it includes both the electroactive material and the current collector in a single electrode. Herein, freestanding electrodes based on rGO/PAni/NiHCF are synthesized through the electrodeposition of NiHCF over rGO/PAni films, enabling control of the amount of NiHCF nanoparticles and the freestanding film thickness. Thinner electrodes achieve specific capacity values of 83 mAh g−1 at the current density of 50 mA g−1 in a three-electrode system, a specific capacity close to 61 mAh g−1 at the current density of 10 mA g−1 in a coin-cell system, approaching the theoretical capacity of NiHCF.
Journal of Power Sources , 2025, 655 237949.