Sequential Effect of Dual‐Layered Hybrid Graphite Anodes on Electrode Utilization During Fast‐Charging Li‐Ion Batteries

• Published in: Advanced science Vol. 11; no. 31; pp. e2403071 - n/a
• Main Authors: Kang, Jiwoong, Lim, Jaejin, Lee, Hyuntae, Park, Seongsu, Bak, Cheol, Shin, Yewon, An, Hyeongguk, Lee, Mingyu, Lee, Minju, Lee, Soyeon, Choi, Byungjun, Kang, Dongyoon, Chae, Sujong, Lee, Yong Min, Lee, Hongkyung
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.08.2024; John Wiley and Sons Inc; Wiley
• Subjects: Carbon; dual‐layered electrodes; Electrodes; Electrolytes; Energy; fast‐charging batteries; Graphene; Graphite; hybrid graphite anodes; resistance distribution; Retention; Spectrum analysis; temporal SOC gradient; hybrid graphite anodes; resistance distribution; dual‐layered electrodes; temporal SOC gradient; fast‐charging batteries
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202403071

To recharge lithium‐ion batteries quickly and safely while avoiding capacity loss and safety risks, a novel electrode design that minimizes cell polarization at a higher current is highly desired. This work presents a dual‐layer electrode (DLE) technology via sequential coating of two different anode materials to minimize the overall electrode resistance upon fast charging. Electrochemical impedance spectroscopy and distribution of relaxation times analysis revealed the dynamic evolution of electrode impedances in synthetic graphite (SG) upon a change in the state of charge (SOC), whereas the natural graphite (NG) maintains its original impedance regardless of SOC variation. This disparity dictates the sequence of the NG and SG coating layers within the DLE, considering the temporal SOC gradient developed upon fast charging. Simulation and experimental results suggest that DLE positioning NG and SG on the top (second‐layer) and bottom (first‐layer), respectively, can effectively reduce the overall resistance at a 4 C‐rate (15‐min charging), demonstrating two times higher capacity retention (61.0%) over 200 cycles than its counterpart with reversal sequential coating, and is higher than single‐layer electrodes using NG or NG/SG binary mixtures. Hence, this study can guide the combinatorial sequence for multi‐layer coating of various active materials for a lower‐resistivity, thick‐electrode design. A dual‐layered, hybrid anode design is proposed to maximize electrode utilization during fast‐charging lithium‐ion cells by leveraging the distinct impedance trends of natural and synthetic graphite anodes as the state of charge (SOC) changes. Combining experiments and simulation studies unlocks the sequential role of the active materials in the dual‐layer coating, considering the temporal SOC distribution that develops during fast‐charging.