Unraveling the Effects of Redox-Active Electrolytes on Carbon Electrodes in Li-Ion Capacitor

The quest for efficient and sustainable energy storage solutions has generated significant interest in lithium-ion capacitors (LICs) due to their balanced power and energy characteristics. This study explores the performance of carbon electrodes in LICs prelithiated with a redox-active electrolyte containing lithium thiocyanate (LiSCN). The impact of thiocyanate on electrode performance is investigated utilizing step potential electrochemical spectroscopy (SPECS) and the galvanostatic intermittent titration technique (GITT). In the studied conditions, the thiocyanate reaction proceeds with an efficiency of ≈81%, resulting in a capacity of 301 mAh g⁻¹ for the positive electrode. Notably, the presence of thiocyanates significantly reduces the resistance of the negative electrode by 30%. Therefore, the addition of LiSCN facilitates lithium intercalation in the negative graphite electrode, enhancing capacity and reducing resistance. The SPECS technique reveals distinct intercalation stages and improved ion diffusion, while GITT confirms these findings with diffusion coefficients. Overall, the study demonstrates the efficacy of using redox-active electrolytes in LICs, presenting a viable path for optimizing their performance in future applications.