Rene Pfeifer

Potassium nitrate (KNO₃) is widely utilized in concentrated solar power tower (CSPT) fuels and as an additive to address the issue of lithium dendrite formation in lithium-ion batteries and CSPT systems. This study investigates the influence of boron-doped diamond (BDD) films and their interaction with KNO₃-saturated solutions to enhance these devices’ efficiency and energy capacity. One critical factor in achieving higher energy devices is the electrochemical stability window (ESW). Consequently, this research examines various properties of BDD, including grain size, doping level, conductivity, carbon-sp³/sp² ratio, and electrolyte characteristics such as conductivity and pH. The results demonstrate that a BDD film grown at a B/C ratio of 2000 ppm, a grain size of 1.75 μm and a carbon-sp³/sp² ratio value of 0.31 achieved the broadest ESW of 3.5 V. Advantageously, the properties of the KNO₃ electrolyte, specifically concentration and pH, had minimal impact on the ESW. Controversially, the ionic conductivity of the electrolyte increased with concentration, with a peak value of 204 mS cm^–1 observed in the supersaturated solution (3.78 mol kg^–1).

Understanding how to tune the properties of electroactive materials is a key parameter for their applications in energy storage systems. This work presents a comprehensive study in tailoring polyaniline (PANI) suspensions by acid‐assisted polymerization method and their subsequent deposition on boron‐doped diamond (BDD) supports with low/high B concentrations. The porous or densely packed morphology of PANI is successfully controlled by varying the monomer‐to‐initiator ratio. The interaction between PANI and BDDs leads to the shift in oxidation and reduction potentials, and the high B doping resulted in the reduction of the oxidation potentials. Notably, the highest specific capacitance of 958 F g ⁻¹ , which represents 90% of the theoretical capacitance, is recorded for the support with relatively low B content. Moreover, PANI obtained by slow kinetic has a stronger interaction with the B‐doped diamond support, which is confirmed by electrochemical impedance spectroscopy. This study provides valuable insights for optimizing PANI suspension preparation methods and selecting appropriate boron doping concentrations in nanodiamond supports for composite electrodes in energy storage applications.