## 1 Introduction  
Commitments to the Paris Climate Agreement force global efforts to reduce greenhouse gas emissions in all sectors. Therefore, in addition to the expansion of renewable energy sources and efficiency improvements, increasing electrification of previously fossil-fueled processes is required. Within the transport sector, battery electric vehicles offer a high potential to achieve the targeted goals, but need increased technology developments to improve their attractiveness. In particular, due to the absence of combustion waste heat, alternative thermal management concepts are necessary to avoid range losses of up to 50% [1,2] during the cold season for heating the interior. Thermal energy storage options [3] extended by electric heating systems are a promising approach facing the challenges ahead, allowing an innovative heat supply instead of today's battery-powered PTC (Positive Temperature Coefficient) heaters. The basic principle is to heat electrically the storage medium parallel of charging the battery, store thermal energy efficiently and to release it at a defined temperature level during vehicle drive. Such thermal storage technologies allow in a time-decoupled operation improvement in systemic flexibility and efficiency and are widely investigated in stationary applications, e.g., industrial [4,5] or power plant [6,7] processes. Depending on the application, media, temperature level or systemic requirements sensible [8,9], latent [10,11] or thermochemically [12,13] based thermal energy storage options are suitable. A transfer of such thermal storage technologies opens up great potentials in the transport sector for future thermal management concepts, but is strongly linked with two crucial requirements: high systemic thermal storage densities and high charging/discharging powers. So far, several studies have been performed for thermal storage systems based on phase change materials (PCM) for heat supply [14,15,16], for preheating of catalysts [17], for combustion engines [18] and for cooling applications [19]. New ways for thermal management concepts based on thermochemical energy storage systems (solid/gas reaction) are described in [20], offering an alternative heat and cold supply especially for fuel cell vehicles. In terms of heating demand, each of those thermal storage technologies opens up great potentials to reach high systemic thermal storage densities or high charging or discharging powers, but show limitations for the overall process. A promising solution to fulfil all requirements is given by electrical heated solid media thermal energy storage systems. Such regenerator-type options enable together with efficient thermal insulations high systemic storage densities due to the use of ceramic materials suitable for high operation temperatures and reach high discharging power densities due to high specific heat transfer surfaces as well as a direct contact between the solid and the fluid phase. Such a storage system with honeycomb-shaped ceramic solids and a bypass concept for controlled discharging outlet temperatures was firstly investigated in [21,22] with vehicle-typical boundary conditions. The results showed-compared to today's battery-powered heating systems as well as to alternative thermal storage systems-high systemic storage densities of up to 160 Wh/kg at constant thermal discharge powers of 5 kW. Additional optimizations with regard to a novel thermal insulation concept were described in [23] and led to further increases of the systemic storage density up to 285 Wh/kg with simultaneously improved operational flexibility. Hereby, one fundamental condition was presupposed in all investigations: a compact and powerful heating system with operating heating temperatures of more than 1000 \({}^{\circ}\)C.  
Today's commercial high-temperature cartridge heaters use resistance-based metallic heating wires embedded within plate- or cylinder-shaped elements in electrically insulating materials.