11:00 AM - EN03.01.07
Challenges and Opportunities for Thick Electrode Batteries and Supercapacitors
Chaoji Chen1,Liangbing Hu1
University of Maryland College Park1
The fast growing demand of portable electronics and electric vehicles has driven the rapid development of rechargeable batteries and supercapacitors in the past forty years. Energy storage devices with higher energy density is desirable for a longer using time or driving range. In pursue of higher energy density, tremendous efforts have been made in the past few decades, mainly via the developing of novel battery chemistries and/or structural engineering. Battery structural engineering is able to improve the energy density of the energy storage devices via optimizing the configurations of electrode and/or battery architecture yet without changing the electrode chemistry, representing a promising direction towards high-energy battery and supercapacitor development. One most attractive battery structural engineering strategy is thick electrode design that is able to increase the ratio of active material and reduce the manufacturing cost by reducing the use of nonactive components in batteries (e.g., current collector, separator, binder, packaging material, electrolyte, etc.). Given the opportunities thick electrode design offered, intensive efforts from the energy storage community have been dedicated, and great progresses have been made recently. However, constructing thick electrode still faces several challenges, including the delamination of electrode slurry from metal current collector during the drying process, scalable manufacturing, and the sluggish charge kinetics.
To address these challenges, Hu’s group has developed several strategies in constructing better thick electrodes for high-energy batteries and supercapacitors. One strategy is constructing three-dimensional (3D) conductive framework with low-tortuosity pores via direct carbonization of natural wood, where various active electrode materials (e.g., lithium iron phosphate, sulfur, manganese dioxide cathode, lithium metal, porous carbon anode) can be infiltrated or deposited with high active material mass loadings [1-3]. To maintain the mechanical robustness of wood, a new strategy was developed to convert natural wood into flexible wood electrode via partial delignification and multiple coating processes, where carbonization is avoided . A cellulose based densified 3D electrode structure was also proposed via conformal coating of carbon black particles on each cellulose nanofiber to impart decoupled pathways for the fast transport of ions and electrons, followed by active material incorporation into the conductive framework and mechanical compression . We will discuss these progresses in thick electrode development from our lab, challenges, and future research opportunities in this field.
 C. Chen, L. Hu Nanocellulose toward Advanced Energy Storage Devices: Structure and Electrochemistry Acc. Chem. Res. 2018, 51, 3154–3165. DOI: 10.1021/acs.accounts.8b00391.
 C. Chen, Y. Zhang, Y. Li, J. Dai, J. Song, Y. Yao, Y. Gong, I.Kierzewski, J. Xie, L. Hu, All-wood, Low Tortuosity, Aqueous, Biodegradable Supercapacitors with Ultra-High Capacitance, Energy Environ. Sci., 2017, 10, 538-545. DOI: 10.1039/C6EE03716J.
 Y. Zhang, W. Luo, C. Wang, Y. Li, C. Chen, J. Song, J. Dai, E. Hitz, S. Xu, C. Yang, Y. Wang, L. Hu High Capacity, Low Tortuosity and Channel-Guided Lithium Metal Anode, PNAS, 2017, 114, 3584-3589. DOI: 10.1073/pnas.1618871114.
 C. Chen, S. Xu, Y. Kuang, W. Gan, J. Song, G. Chen, G. Pastel, H. Huang, B. Liu, Y. Li, L. Hu Nature-Inspired Tri-Pathway Design Enabling High-Performance Flexible Li-O2 Batteries. Adv. Energy Mater. 2019, 9, 1802964. DOI: 10.1002/aenm.201802964.
 Y. Kuang, C. Chen, G. Pastel, Y. Li, J. Song, R. Mi, W. Kong, B. Liu, Y. Jiang, K. Yang, L. Hu Conductive Cellulose Nanofiber Enabled Thick Electrode for Compact and Flexible Energy Storage Devices. Adv. Energy Mater. 2018, https://doi.org/10.1002/aenm.201802398.