A practical high-energy lithium-ion capacitor enabled by multiple conducting bridges triggered electrode current reallocation

Abstract

Lithium-ion capacitors (LICs), consisting of a battery-type anode and capacitive cathode, hold great promise for achieving high-energy and high-power densities. However, the sluggish migration of electrons and ions in the anode hinders the attainment of the "dual-high" target. To circumvent this obstacle, we propose a novel strategy employing multiple conducting bridges to augment charge dynamics for the hard carbon (HC) anode and activated carbon (AC) cathode. In this approach, graphene nanosheets are deposited in-situ via a self-propagating high-temperature synthesis methodology to establish connections between isolated HC (or AC) powders. Subsequently, carbon nanotubes are introduced to fill the inter-particle gaps, forming a network of multiple conducting bridges. Through the experimental investigation and finite elemental simulation, we demonstrate that this approach triggers prompt inter-particle electrons and ions migration, resulting in a homogeneous redistribution of the current at the electrode scale. This engenders a substantial enhancement in electronic conductivity (∼3 fold), and a significant improvement in the ion diffusion. Consequently, we fabricate a 1000 F LIC pouch cell displaying a state-of-the-art device performance of 30.3 W h kg−1 and 8.1 kW kg−1, coupled with a remarkable cycle life of 87.9% retention after 10,000 cycles. This study thus represents a distinctive avenue for regulating charge dynamics at the electrode scale and optimizing the performance of practical LICs.