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Title: Operando identification of the point of [Mn 2 ]O 4 spinel formation during γ-MnO 2 discharge within batteries

Authors:
ORCiD logo; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1354463
Report Number(s):
BNL-112980-2016-JA
Journal ID: ISSN 0378-7753
DOE Contract Number:
SC00112704
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Power Sources; Journal Volume: 321
Country of Publication:
United States
Language:
English

Citation Formats

Gallaway, Joshua W., Hertzberg, Benjamin J., Zhong, Zhong, Croft, Mark, Turney, Damon E., Yadav, Gautam G., Steingart, Daniel A., Erdonmez, Can K., and Banerjee, Sanjoy. Operando identification of the point of [Mn 2 ]O 4 spinel formation during γ-MnO 2 discharge within batteries. United States: N. p., 2016. Web. doi:10.1016/j.jpowsour.2016.05.002.
Gallaway, Joshua W., Hertzberg, Benjamin J., Zhong, Zhong, Croft, Mark, Turney, Damon E., Yadav, Gautam G., Steingart, Daniel A., Erdonmez, Can K., & Banerjee, Sanjoy. Operando identification of the point of [Mn 2 ]O 4 spinel formation during γ-MnO 2 discharge within batteries. United States. doi:10.1016/j.jpowsour.2016.05.002.
Gallaway, Joshua W., Hertzberg, Benjamin J., Zhong, Zhong, Croft, Mark, Turney, Damon E., Yadav, Gautam G., Steingart, Daniel A., Erdonmez, Can K., and Banerjee, Sanjoy. 2016. "Operando identification of the point of [Mn 2 ]O 4 spinel formation during γ-MnO 2 discharge within batteries". United States. doi:10.1016/j.jpowsour.2016.05.002.
@article{osti_1354463,
title = {Operando identification of the point of [Mn 2 ]O 4 spinel formation during γ-MnO 2 discharge within batteries},
author = {Gallaway, Joshua W. and Hertzberg, Benjamin J. and Zhong, Zhong and Croft, Mark and Turney, Damon E. and Yadav, Gautam G. and Steingart, Daniel A. and Erdonmez, Can K. and Banerjee, Sanjoy},
abstractNote = {},
doi = {10.1016/j.jpowsour.2016.05.002},
journal = {Journal of Power Sources},
number = ,
volume = 321,
place = {United States},
year = 2016,
month = 7
}
  • The rechargeability of γ-MnO 2 cathodes in alkaline batteries is limited by the formation of the [Mn 2]O 4 spinels ZnMn 2O 4 (hetaerolite) and Mn 3O 4 (hausmannite). However, the time and formation mechanisms of these spinels are not well understood. Here we directly observe γ-MnO 2 discharge at a range of reaction extents distributed across a thick porous electrode. Coupled with a battery model, this reveals that spinel formation occurs at a precise and predictable point in the reaction, regardless of reaction rate. Observation is accomplished by energy dispersive X-ray diffraction (EDXRD) using photons of high energy andmore » high flux, which penetrate the cell and provide diffraction data as a function of location and time. After insertion of 0.79 protons per γ-MnO 2 the α-MnOOH phase forms rapidly. α-MnOOH is the precursor to spinel, which closely follows. ZnMn 2O 4 and Mn 3O 4 form at the same discharge depth, by the same mechanism. The results show the final discharge product, Mn 3O 4 or Mn(OH) 2, is not an intrinsic property of γ-MnO 2. While several studies have identified Mn(OH) 2 as the final γ-MnO 2 discharge product, we observe direct conversion to Mn 3O 4 with no Mn(OH) 2.« less
  • Alloying anode materials offer high capacity for next-generation batteries, but the performance of these materials often decays rapidly with cycling because of volume changes and associated mechanical degradation or fracture. The direct measurement of crystallographic strain evolution in individual particles has not been reported, however, and this level of insight is critical for designing mechanically resilient materials. Here, we use operando X-ray diffraction to investigate strain evolution in individual germanium microparticles during electrochemical reaction with lithium. The diffraction peak was observed to shift in position and diminish in intensity during reaction because of the disappearance of the crystalline Ge phase.more » The compressive strain along the [111] direction was found to increase monotonically to a value of -0.21%. This finding is in agreement with a mechanical model that considers expansion and plastic deformation during reaction. This new insight into the mechanics of large-volume-change transformations in alloying anodes is important for improving the durability of high-capacity batteries.« less
  • Pristine Li-rich layered cathodes, such as Li1.2Ni0.2Mn0.6O2 and Li1.2Ni0.1Mn0.525Co0.175O2, were identified to exist in two different structures: LiMO2 R-3m and Li2MO3 C2/m phases. Upon charge/discharge cycling, both phases gradually transform to the spinel structure. The transition from LiMO2 R-3m to spinel is accomplished through the migration of transition metal ions to the Li site without breaking down the lattice, leading to the formation of mosaic structured spinel grains within the parent particle. In contrast, transition from Li2MO3 C2/m to spinel involves removal of Li+ and O2-, which produces a large lattice strain and leads to the breakdown of the parentmore » lattice and therefore the newly formed spinel grains show random orientation within the same particle. Cracks and pores were also noticed within some particles, which is believed to be the consequence of the breakdown of the lattice and vacancy condensation upon removal of lithium ions. The presently observed structure transition characteristics provide direct reasons for the observed gradual capacity loss and poor rate performance of the layered composite. Ultimately it also provides clues about how to improve the materials structure with potential improved performance.« less
  • Virtually all intercalation compounds used as battery electrodes exhibit significant changes in unit cell volume during use. Na xFePO 4 (0 < x < 1, NFP) olivine, of interest as a cathode for sodium-ion batteries, is a model for topotactic, high strain systems as it exhibits one of the largest discontinuous volume changes (~17% by volume) during its first-order transition between two otherwise isostructural phases. Using synchrotron radiation powder X-ray diffraction (PXD) and pair distribution function (PDF) analysis, we discover a new strain-accommodation mechanism wherein a third, <10 nm scale nanocrystalline phase forms to buffer the large lattice mismatch betweenmore » primary phases. The new phase has a and b lattice parameters matching one crystalline endmember phase and c lattice parameter matching the other, and is not detectable by powder diffraction alone. Finally, we suggest that this strain-accommodation mechanism may apply to systems with large transformation strains but in which true “amorphization” does not occur.« less