Facile fabrication of few-layer nanostructured MoSe2 entrenched on N-doped carbon as a superior anode material for high-performance potassium-ion hybrid capacitors

As an emerging class of advanced capacitor-battery hybrid energy storage and transformation devices, potassium ion hybrid capacitors (PIHCs) have become the next generation of electrochemical energy storage systems owing to their abundant ratio of raw materials and inexpensive potassium resources. However, potassium ions have backward kinetics because of their ionic radius. Therefore, the improvement of applicable materials with powerful capacity and rapid charge and discharge capabilities remains a large challenge. Here, we design simple hydrothermal synthesis methods to anchor MoSe ₂ nanosheets into a 3-dimensional N-doped porous carbon skeleton as a fast, durable electrode to boost energy storage for PIHCs. Specifically, highly conductive 3-dimensional N-doped porous carbon skeleton materials can efficiently alleviate the accumulation of MoSe ₂ nanosheets and facilitate electron diffusion. It is demonstrated that MoSe ₂ /NC utilized as potassium ion battery anodes exhibits a reversible capacity (415.1 mA h g ⁻¹ at 100 mA g ⁻¹) and a superior rate performance (212.4 mAh g ⁻¹ at 5000 mA g ⁻¹ ) as a result of its unique nanostructure and powerful chemical interactions between MoSe ₂ nanosheets and N-doped carbon skeletons. As a result of its use of an anode of MoSe ₂ /NC and a cathode of activated carbon, the PIHCs can provide an extremely high energy density of 136.8 Wh kg ⁻¹ accompanied by a power density of 400 W kg ⁻¹ excellent rate performance and an exceptionally long-cycle lifespan.