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

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.