Novel Lithium‐Ion Capacitor Based on TiSb₂ as Negative Electrode: The Role of Mass Ratio towards High Energy‐to‐Power Densities and Long Cyclability

Abstract In this work lithium ion capacitors (LICs) built using a TiSb₂ alloy as the negative electrode and activated carbon (AC) derived from recycled olive pits biomass as the positive electrode are reported. TiSb₂ shows high capacity (360 mAh g⁻¹ at 10 C) and excellent rate capability performance together with exceptional volumetric features, enabling its use as a promising candidate for high power requiring technologies. So far, to the best of our knowledge, this is the first Sb alloy‐based LIC ever reported. In order to maximize the output performance, the influence of the mass ratio of the active materials (TiSb₂ : AC) is studied. The best TiSb₂‐based LIC is able to deliver an energy density as high as 167 Wh kg_AM⁻¹ (78 Wh dm⁻³) at 115 W kg_AM⁻¹ (53 W dm⁻³), more than a 6‐fold increase with respect to its EDLC counterpart. Under high power demanding situations, i. e., 11 kW kg_AM⁻¹ (6 kW dm⁻³), it retains up to 90 Wh kg_AM⁻¹ (48 Wh dm⁻³), which is among the best reported values for LICs. In addition, the device with the most appropriate mass ratio presents an encouraging 80 % retention of the initial capacitance after 10000 charge‐discharge cycles at t_discharge=11 s.