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Title: Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries

Abstract

For LiMO 2 (M=Co, Ni, Mn) cathode materials, lattice parameters, a(b), contract during charge. Here we report such changes in opposite directions for lithium molybdenum trioxide (Li 2MoO 3). A ‘unit cell breathing’ mechanism is proposed based on crystal and electronic structural changes of transition metal oxides during charge-discharge. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of the metal-metal bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking metal-oxygen bond as controlling factor in ‘normal’ materials. The cation mixing caused by migration of molybdenum ions at higher oxidation state provides the benefits of reducing the c expansion range in the early stage of charging and suppressing the structure collapse at high voltage charge. These results may open a new strategy for designing layered cathode materials for high energy density lithium-ion batteries.

Authors:
; ; ; ; ; ; ; ;  [1];  [2];  [2]
  1. BNL
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - NUCLEAR ENERGYFOREIGN
OSTI Identifier:
1168481
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nat. Commun.; Journal Volume: 5; Journal Issue: 2014
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Zhou, Yong-Ning, Ma, Jun, Hu, Enyuan, Yu, Xiqian, Gu, Lin, Nam, Kyung-Wan, Chen, Liquan, Wang, Zhaoxiang, Yang, Xiao-Qing, Chinese Aca. Sci.), and Dongguk). Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries. United States: N. p., 2014. Web. doi:10.1038/ncomms6381.
Zhou, Yong-Ning, Ma, Jun, Hu, Enyuan, Yu, Xiqian, Gu, Lin, Nam, Kyung-Wan, Chen, Liquan, Wang, Zhaoxiang, Yang, Xiao-Qing, Chinese Aca. Sci.), & Dongguk). Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries. United States. doi:10.1038/ncomms6381.
Zhou, Yong-Ning, Ma, Jun, Hu, Enyuan, Yu, Xiqian, Gu, Lin, Nam, Kyung-Wan, Chen, Liquan, Wang, Zhaoxiang, Yang, Xiao-Qing, Chinese Aca. Sci.), and Dongguk). 2014. "Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries". United States. doi:10.1038/ncomms6381.
@article{osti_1168481,
title = {Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries},
author = {Zhou, Yong-Ning and Ma, Jun and Hu, Enyuan and Yu, Xiqian and Gu, Lin and Nam, Kyung-Wan and Chen, Liquan and Wang, Zhaoxiang and Yang, Xiao-Qing and Chinese Aca. Sci.) and Dongguk)},
abstractNote = {For LiMO2 (M=Co, Ni, Mn) cathode materials, lattice parameters, a(b), contract during charge. Here we report such changes in opposite directions for lithium molybdenum trioxide (Li2MoO3). A ‘unit cell breathing’ mechanism is proposed based on crystal and electronic structural changes of transition metal oxides during charge-discharge. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of the metal-metal bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking metal-oxygen bond as controlling factor in ‘normal’ materials. The cation mixing caused by migration of molybdenum ions at higher oxidation state provides the benefits of reducing the c expansion range in the early stage of charging and suppressing the structure collapse at high voltage charge. These results may open a new strategy for designing layered cathode materials for high energy density lithium-ion batteries.},
doi = {10.1038/ncomms6381},
journal = {Nat. Commun.},
number = 2014,
volume = 5,
place = {United States},
year = 2014,
month =
}
  • Through a systematic study of lithium molybdenum trioxide (Li 2MoO 3), a new ‘unit cell breathing’ mechanism is introduced based on both crystal and electronic structural changes of transition metal oxide cathode materials during charge–discharge: For widely used LiMO 2 (M = Co, Ni, Mn), lattice parameters, a and b, contracts during charge. However, for Li 2MoO 3, such changes are in opposite directions. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of M–M bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking M–O asmore » controlling factor in ‘normal’ materials. The cation mixing caused by migration of Mo ions at higher oxidation state provides the benefits of reducing the c expansion range in early stage of charging and suppressing the structure collapse at high voltage charge. These results open a new strategy for designing and engineering layered cathode materials for high energy density lithium-ion batteries.« less
  • To evaluate the effect of transition metal composition on the electrochemical properties of Li-rich layer-structured cathode materials, Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2, 0.25, 0.3, and 0.4) were synthesized, and their electrochemical properties were investigated. As nickel content x increased in Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2, 0.25, 0.3, and 0.4), charge-discharge capacities at a low C-rate (0.05 C) decreased. The results obtained by dQ/dV curves indicate that, as the nickel content increased, the discharge capacity below 3.6 V greatly decreased, but that above 3.6 V increased. As the C-rate of the discharge process increased, the discharge reaction of Li{submore » 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2) below 3.6 V greatly decreased. In contrast, that above 3.6 V slightly decreased. This indicates that the discharge reaction above 3.6 V exhibits higher rate performance than that below 3.6 V. For the high-nickel-content cathodes, the ratio of the discharge capacity above 3.6 V to the total discharge capacity was high. Therefore, they exhibited high rate performance. - Graphical abstract: Figure shows the discharge curves of Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2 and 0.3) within potential range of 2.5−4.6 V (vs. Li/Li{sup +}) at 0.05 and 3 C. At low C-rate (0.05 C), the discharge capacity of high-nickel-content cathode (Li{sub 1.2}Ni{sub 0.3}Mn{sub 0.5}O{sub 2}) was less than that of low-nickel-content cathode (Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2}); however, the discharge potential and capacity of Li{sub 1.2}Ni{sub 0.3}Mn{sub 0.5}O{sub 2} was higher than those of Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} at high C-rate (3 C). This means that the increase in Ni/Mn ratio was effective in improving rate-performance.« less
  • Using fast time-resolved in situ X-ray diffraction, charge-rate dependent phase transition processes of layer structured cathode material LiNi 1/3Mn 1/3Co 1/3O 2 for lithium-ion batteries are studied. During first charge, intermediate phases emerge at high rates of 10C, 30C, and 60C, but not at low rates of 0.1C and 1C. These intermediate phases can be continuously observed during relaxation after the charging current is switched off. After half-way charging at high rate, sample studied by scanning transmission electron microscopy shows Li-rich and Li-poor phases' coexistence with tetrahedral occupation of Li in Li-poor phase. Also, the high rate induced overpotential ismore » thought to be the driving force for the formation of this intermediate Li-poor phase. The in situ quick X-ray absorption results show that the oxidation of Ni accelerates with increasing charging rate and the Ni 4+ state can be reached at the end of charge with 30C rate. Finally, these results give new insights in the understanding of the layered cathodes during high-rate charging.« less