A Synergistic Anode Strategy for Fast and Durable Lithium-Ion Battery Capacitors

Lithium-ion battery capacitors (LIBCs) have gained attention as promising energy storage systems that narrow the performance disparity between lithium-ion batteries and supercapacitors. However, conventional anode materials such as graphite (Gr), suffer from sluggish lithium-ion intercalation kinetics and safety risks at high rates, while soft carbon (SC) faces limitations including low capacity and wide voltage window. To address these challenges, we design a Gr/SC hybrid anode that synergistically combines the advantages of both materials. Hybrid anodes with varying mass ratios were fabricated, and their structural features and electrochemical behaviors were systematically investigated. The findings display that the hybrid anodes effectively combine the beneficial characteristics of Gr and SC, offering enhanced conductivity, improved rate capability, and superior cycling stability. Current distribution test was applied for the first time to explore the synergistic effect between two components in hybrid anode, indicating its suitability for fast and durable devices. Moreover, the distribution of relaxation times (DRT) and galvanostatic intermittent titration technique (GITT) results reveal favorable lithium-ion transport dynamics. The hybrid anode LIBC with a Gr to SC ratio of 1:1 achieves 318.4 Wh kg −1 at 0.09 kW kg −1 and 56.3 Wh kg −1 at 15.6 kW kg −1 , with 87.9% capacity after 2,000 cycles, demonstrating excellent electrochemical performance. Anode potential analysis further confirms suppressed lithium dendrite growth and electrolyte degradation, contributing to enhanced operational safety. Overall, this work demonstrates that the Gr/SC hybrid anode effectively resolves the trade-off between power performance and safety in LIBCs, offering a practical approach for next-generation fast-charging batteries. • A Gr/SC hybrid anode synergistically combines both advantages for LIBCs. • Current distribution is first used to probe real-time synergy between Gr and SC. • DRT and GITT analyses confirm improved Li + diffusion and homogeneous intercalation. • The full LIBC shows excellent performance and 87.9% capacity after 2000 cycles. • Anode potential analysis displays the hybrid LIBC balances safety and capacity.