TY - JOUR
T1 - Freeze-dried low-tortuous graphite electrodes with enhanced capacity utilization and rate capability
AU - Dang, Dingying
AU - Wang, Yikai
AU - Gao, Shuang
AU - Cheng, Yang Tse
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2020/4/15
Y1 - 2020/4/15
N2 - Lithium ion battery electrodes with high rate capability are important for extreme fast charging (XFC) for electric vehicle applications. Making low-tortuous electrodes is one of the approaches to achieve XFC by enhancing ionic transport in the electrodes. In this study, we conducted directional freeze-drying of slurries cast on a copper foil to make graphite electrodes. Low-tortuous structure was created and verified by cross-sectional scanning electron microscope observations and tortuosity measurements. The out-of-plane alignment of graphite flakes, enhanced electrolyte wettability, and low tortuosity of the freeze-dried electrodes were confirmed by X-ray diffraction measurements, wettability tests, and electrochemical impedance measurements, respectively. Electrochemical measurements showed that the freeze-dried electrodes have higher capacity retention (over 8% higher after 90 cycles at C/5) and better rate capability (60% higher capacity at 1C) than the electrodes prepared by the conventional tape-casting method. These enhancements mainly arise from the improved ionic transport by the freeze-drying induced low-tortuous structure. This study provides a proof-of-concept example that tape-casting/freeze-drying can be an effective, low cost, and scalable method to reduce tortuosity and improve electrochemical performance of battery electrodes.
AB - Lithium ion battery electrodes with high rate capability are important for extreme fast charging (XFC) for electric vehicle applications. Making low-tortuous electrodes is one of the approaches to achieve XFC by enhancing ionic transport in the electrodes. In this study, we conducted directional freeze-drying of slurries cast on a copper foil to make graphite electrodes. Low-tortuous structure was created and verified by cross-sectional scanning electron microscope observations and tortuosity measurements. The out-of-plane alignment of graphite flakes, enhanced electrolyte wettability, and low tortuosity of the freeze-dried electrodes were confirmed by X-ray diffraction measurements, wettability tests, and electrochemical impedance measurements, respectively. Electrochemical measurements showed that the freeze-dried electrodes have higher capacity retention (over 8% higher after 90 cycles at C/5) and better rate capability (60% higher capacity at 1C) than the electrodes prepared by the conventional tape-casting method. These enhancements mainly arise from the improved ionic transport by the freeze-drying induced low-tortuous structure. This study provides a proof-of-concept example that tape-casting/freeze-drying can be an effective, low cost, and scalable method to reduce tortuosity and improve electrochemical performance of battery electrodes.
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U2 - 10.1016/j.carbon.2019.12.036
DO - 10.1016/j.carbon.2019.12.036
M3 - Article
AN - SCOPUS:85076696916
SN - 0008-6223
VL - 159
SP - 133
EP - 139
JO - Carbon
JF - Carbon
ER -