Anomalous decrease in structural disorder due to charge redistribution in Cr-doped Li4Ti5O12 negative-electrode materials for high-rate Li-ion batteries
- Anomalous decrease in structural disorder due to charge redistribution in Cr-doped Li4Ti5O12 negative-electrode materials for high-rate Li-ion batteries
- 송한나; 윤수원; 천호환; 김민규; 정경윤; 김형선; 조병원; 김용태
- Li4Ti5O12; Cr-doping; Cathode; structural disorder
- Issue Date
- Energy & environmental science
- VOL 5, NO 12, 9903-9913
- Since one of the main drawbacks of Li4Ti5O12 as a negative-electrode material is its low electronic conductivity, several researchers have attempted to improve the conductivity by narrowing the band gap through transition-metal doping. Herein, we report another, more significant effect of doping in addition to the band gap narrowing, namely, an anomalous decrease in the structural disorder in Li4Ti5O12 upon Cr3+-ion doping. Although it is generally recognized that doping with heterogeneous elements increases the structural disorder, the Cr3+-ion doping in Li4Ti5O12 demonstrated an unexpected structural phenomenon. From the results of various structural analyses using a synchrotron beam, such anomalous structural changes were revealed to originate from charge redistribution at nearby Ti4+ ions. Finally, the capacity was markedly enhanced, especially at high C-rates (125 mA h g−1 for 10C charge/10C discharge, 145 mA h g−1 for 1C charge/50C discharge) because of both the band gap narrowing and the increased ionic diffusivity due to the decreased structural disorder, but was decreased instead for too-high doping levels.
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