The combination of MoS2/reduced graphene oxide composite electrode and ionic liquid for high-temperature supercapacitor

Increasing the temperature range of electrochemical energy storage devices represents one of the most interesting sectors in the energy field. In fact, there are countless applications in which the current temperature range is not able to satisfy the applicant's requests and, unfortunately, traditional energy storage devices are not able to sustain these harsh conditions. Among all, supercapacitors emerged as possible candidates to solve this problem, but a lot of research efforts should be spent to overcome the actual limitations. Herein we report on the fabrication of a supercapacitor able to achieve the working temperature of 200 °C exploiting a 3D graphene aerogel decorated with nanostructured MoS2 in combination with an ionic liquid electrolyte able to warranty an effective energy storage performance even at high temperature. The proposed device exhibits capacitance values up to 210 F/g (corresponding to 365 mF/cm2) at 200 °C with a voltage window equal to 2.1 V, resulting in a 20 % improvement of performance from RT to 200 °C, overcoming the existing literature in the field. In fact, the rated value corresponds to an energy of 0.22 Wh dm−3 in a coin-cell embodiment, one order of magnitude higher compared to the device which reaches the highest temperature commercially available of 175 °C. Moreover, the same device can practically be employed in the whole temperature range from 25 °C up to 250 °C with small performance fluctuations.