Solution-Based Deep Prelithiation for Lithium-Ion Capacitors with High Energy Density

Abstract

Lithium-ion capacitors (LICs) exhibit superior power density and cyclability compared to lithium-ion batteries. However, the low initial Coulombic efficiency (ICE) of amorphous carbon anodes (e.g., hard carbon (HC) and soft carbon (SC)) limits the energy density of LICs by underutilizing cathode capacity. Here, a solution-based deep prelithiation strategy for carbon anodes is applied using a contact-ion pair dominant solution, offering high energy density based on a systematic electrode balancing based on the cathode capacity increased beyond the original theoretical limit. Increasing the anode ICE to 150% over 100%, the activated carbon (AC) capacity is doubled by activating Li+ cation storage, which unleashes rocking-chair LIC operation alongside the dual-ion-storage mechanism. The increased AC capacity results in an energy density of 106.6 Wh kg-1AC+SC, equivalent to 281% of that of LICs without prelithiation. Moreover, this process lowers the cathode-anode mass ratio, reducing the cell thickness by 67% without compromising the cell capacity. This solution-based deep chemical prelithiation promises high-energy LICs based on transition metal-free, earth-abundant active materials to meet the practical demands of power-intensive applications. A solution-based deep prelithiation of carbon anodes is proposed to maximize the energy density of lithium-ion capacitors, enabled by the spontaneous charge transfer from contact-ion pair dominant solutions to the anodes. The deep prelithiation, achieving 150% anode ICE, unleashes Li+ ion storage in cathodes, doubling the cathode capacity. This results in a reduced cell thickness by 67% without compromising capacity. image