TY - JOUR
T1 - Degradation Mechanism of Conversion-Type Iron Trifluoride
T2 - Toward Improvement of Cycle Performance
AU - Senoh, Hiroshi
AU - Matsui, Keitaro
AU - Shikano, Masahiro
AU - Okumura, Toyoki
AU - Kiuchi, Hisao
AU - Shimoda, Keiji
AU - Yamanaka, Keisuke
AU - Ohta, Toshiaki
AU - Fukunaga, Toshiharu
AU - Sakaebe, Hikari
AU - Matsubara, Eiichiro
N1 - Funding Information:
This work was financially supported by the New Energy and Industrial Technology Development Organization (NEDO) under the RISING2 project. The synchrotron radiation experiments were performed at the BL28XU in SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2016A7601, 2016B7607 2017A7607, 2017B7607, 2018A7607, and 2018B7607). We thank Prof. Jun-ichi Yamaki, Dr. Tsuyoshi Takami, Dr. Tomoya Kawaguchi, Dr. Titus Masese and Dr. Hironori Kobayashi for useful discussions. We also acknowledge Dr. Koji Nakanishi and Dr. Masashi Yoshimura for measurement of XAFS Dr. Kazuki Yoshii for measurement of HAXPES, and Katsunori Tashita Yoshihiko Nagoshi, Yasuhiro Nishida, Yuujirou Ikeda, and Naoki Tsujikawa for technical help during conducting the sample preparations and electrochemical measurements.
Funding Information:
This work was financially supported by the New Energy and Industrial Technology Development Organization (NEDO) under the RISING2 project. The synchrotron radiation experiments were performed at the BL28XU in SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2016A7601, 2016B7607, 2017A7607, 2017B7607, 2018A7607, and 2018B7607). We thank Prof. Jun-ichi Yamaki, Dr. Tsuyoshi Takami, Dr. Tomoya Kawaguchi, Dr. Titus Masese, and Dr. Hironori Kobayashi for useful discussions. We also acknowledge Dr. Koji Nakanishi and Dr. Masashi Yoshimura for measurement of XAFS, Dr. Kazuki Yoshii for measurement of HAXPES, and Katsunori Tashita, Yoshihiko Nagoshi, Yasuhiro Nishida, Yuujirou Ikeda, and Naoki Tsujikawa for technical help during conducting the sample preparations and electrochemical measurements.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/8/28
Y1 - 2019/8/28
N2 - Conversion-type iron trifluoride (FeF3) has attracted considerable attention as a positive electrode material for lithium secondary batteries due to its high energy density and low cost. However, the conversion process through which FeF3 operates leads it to suffer from capacity degradation upon repeated cycling. To improve the cycle performance, in this study we investigated the degradation mechanism of conversion-type FeF3 electrode material. Bulk analyses of FeF3 upon cycling reveal incomplete oxidation to Fe3+ concomitant with the aggregation of LiF at the charged state. In addition, surface analyses of FeF3 reveal that a film covered the electrode surface after 10 cycles, which leads to a remarkable increase in resistance. We show that the choice of the electrolyte formulation is crucial in preventing the formation of the film on the electrode surface; thus, FeF3 shows better performance in an electrolyte comprising LiBF4 solute in cyclic carbonate solvents than in chain carbonate-containing LiPF6 as the electrolyte. This study underpins that a careful selection of solvent, rather than solute, is significantly essential to improve the cycle performance of the FeF3 electrode.
AB - Conversion-type iron trifluoride (FeF3) has attracted considerable attention as a positive electrode material for lithium secondary batteries due to its high energy density and low cost. However, the conversion process through which FeF3 operates leads it to suffer from capacity degradation upon repeated cycling. To improve the cycle performance, in this study we investigated the degradation mechanism of conversion-type FeF3 electrode material. Bulk analyses of FeF3 upon cycling reveal incomplete oxidation to Fe3+ concomitant with the aggregation of LiF at the charged state. In addition, surface analyses of FeF3 reveal that a film covered the electrode surface after 10 cycles, which leads to a remarkable increase in resistance. We show that the choice of the electrolyte formulation is crucial in preventing the formation of the film on the electrode surface; thus, FeF3 shows better performance in an electrolyte comprising LiBF4 solute in cyclic carbonate solvents than in chain carbonate-containing LiPF6 as the electrolyte. This study underpins that a careful selection of solvent, rather than solute, is significantly essential to improve the cycle performance of the FeF3 electrode.
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U2 - 10.1021/acsami.9b10105
DO - 10.1021/acsami.9b10105
M3 - Article
C2 - 31390177
AN - SCOPUS:85071715791
VL - 11
SP - 30959
EP - 30967
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 34
ER -