skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Disintegration of Meatball Electrodes for LiNi x Mn y Co z O 2 Cathode Materials

Abstract

Mechanical degradation of Li-ion batteries caused by the repetitive swelling and shrinking of electrodes upon electrochemical cycles is now well recognized. Structural disintegration of the state-of-art cathode materials of a hierarchical structure is relatively less studied. In this paper, we track the microstructural evolution of different marked regimes in LiNi x Mn y Co z O 2 (NMC) electrodes after lithiation cycles. Decohesion of primary particles constitutes the major mechanical degradation in the NMC materials, which results in the loss of connectivity of the conductive network and impedance increase. We find that the structural disintegration is largely dependent on the charging rate – slow charging causes more damage, and is relatively insensitive to the cyclic voltage window. We use finite element modeling to study the evolution of Li concentration and stresses in a NMC secondary particle and employ the cohesive zone model to simulate the interfacial fracture between primary particles. Finally, we reveal that microcracks accumulate and propagate during the cyclic lithiation and delithiation at a slow charging rate.

Authors:
 [1];  [1];  [1];  [2];  [1]
  1. Purdue Univ., West Lafayette, IN (United States). School of Mechanical Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Energy and Transportation Science Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Purdue Univ., West Lafayette, IN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); National Science Foundation (NSF); Office of Naval Research (ONR) (United States)
OSTI Identifier:
1424455
Grant/Contract Number:
AC05-00OR22725; CBET-1603866
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Experimental Mechanics
Additional Journal Information:
Journal Volume: 58; Journal Issue: 4; Journal ID: ISSN 0014-4851
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 42 ENGINEERING; fracture; NMC; stresses; primary particles; Li-ion batteries

Citation Formats

Xu, R., de Vasconcelos, L. S., Shi, J., Li, J., and Zhao, K.. Disintegration of Meatball Electrodes for LiNi x Mn y Co z O2 Cathode Materials. United States: N. p., 2017. Web. doi:10.1007/s11340-017-0292-0.
Xu, R., de Vasconcelos, L. S., Shi, J., Li, J., & Zhao, K.. Disintegration of Meatball Electrodes for LiNi x Mn y Co z O2 Cathode Materials. United States. doi:10.1007/s11340-017-0292-0.
Xu, R., de Vasconcelos, L. S., Shi, J., Li, J., and Zhao, K.. Fri . "Disintegration of Meatball Electrodes for LiNi x Mn y Co z O2 Cathode Materials". United States. doi:10.1007/s11340-017-0292-0. https://www.osti.gov/servlets/purl/1424455.
@article{osti_1424455,
title = {Disintegration of Meatball Electrodes for LiNi x Mn y Co z O2 Cathode Materials},
author = {Xu, R. and de Vasconcelos, L. S. and Shi, J. and Li, J. and Zhao, K.},
abstractNote = {Mechanical degradation of Li-ion batteries caused by the repetitive swelling and shrinking of electrodes upon electrochemical cycles is now well recognized. Structural disintegration of the state-of-art cathode materials of a hierarchical structure is relatively less studied. In this paper, we track the microstructural evolution of different marked regimes in LiNi x Mn y Co z O2 (NMC) electrodes after lithiation cycles. Decohesion of primary particles constitutes the major mechanical degradation in the NMC materials, which results in the loss of connectivity of the conductive network and impedance increase. We find that the structural disintegration is largely dependent on the charging rate – slow charging causes more damage, and is relatively insensitive to the cyclic voltage window. We use finite element modeling to study the evolution of Li concentration and stresses in a NMC secondary particle and employ the cohesive zone model to simulate the interfacial fracture between primary particles. Finally, we reveal that microcracks accumulate and propagate during the cyclic lithiation and delithiation at a slow charging rate.},
doi = {10.1007/s11340-017-0292-0},
journal = {Experimental Mechanics},
number = 4,
volume = 58,
place = {United States},
year = {Fri May 12 00:00:00 EDT 2017},
month = {Fri May 12 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:
  • Thermal stability of charged LiNi xMn yCo zO 2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and themore » larger amount of oxygen release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3¯m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3¯m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. As a result, this systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.« less
  • Direct observations of local lattice aluminum environments have been a major challenge for aluminum -bearing Li ion battery materials, such as LiNi1-y-zCoyAlzO2 Al(NCA) and aluminum-doped LiNixMnyCozO2 (NMC). Al-27 magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and nonlattice (i.e., surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aidmore » of first-principles DFT calculations, we show direct evidence of lattice Al sites, nonpreferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum -"doped" NMC. Aluminum coordination of the paramagnetic (lattice) and diamagnetic (nonlattice) nature is investigated for Al-doped NMC and NCA. For the latter, the evolution of the lattice site(s) upon cycling is also studied. A clear reordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling.« less
  • In this study, we use in-situ transmission electron microcopy (TEM) to investigate the thermal decomposition that occurs at the surface of charged Li xNi yMn zCo 1-y-zO 2 (NMC) cathode materials of different composition (with y, z=0.8, 0.1 and 0.6, 0.2 and 0.4, 0.3), after they have been charged to their practical upper limit voltage (4.3V). By heating these materials inside the TEM, we are able to directly characterize near surface changes in both their electronic structure (using electron energy loss spectroscopy) and crystal structure and morphology (using electron diffraction and bright-field imaging). The most Ni-rich material (y, z =more » 0.8, 0.1) is found to be thermally unstable at significantly lower temperatures than the other compositions – this is manifested by changes in both the electronic structure and the onset of phase transitions at temperatures as low as 100°C. Electron energy loss spectroscopy indicates that the thermally induced reduction of Ni ions drives these changes, and that this is exacerbated by the presence of an additional redox reaction that occurs at 4.2V in the y, z = 0.8, 0.1 material. Exploration of individual particles shows that there are substantial variations in the onset temperatures and overall extent of these changes. Of the compositions studied, the composition of y, z = 0.6, 0.2 has the optimal combination of high energy density and reasonable thermal stability. The observations herein demonstrate that real time electron microscopy provide direct insight into the changes that occur in cathode materials with temperature, allowing optimization of different alloy concentrations to maximize overall performance.« less
  • Ni-rich lithium transition metal oxides have received significant attention due to their high capacities and rate capabilities determined via theoretical calculations. Although the structural properties of these materials are strongly correlated with the electrochemical performance, their structural stability during the high-rate electrochemical reactions has not been fully evaluated yet. In this work, transmission electron microscopy is used to investigate the crystallographic and electronic structural modifications of Ni-based cathode materials at a high charge/discharge rate of 10 C. It is found that the high-rate electrochemical reactions induce structural inhomogeneity near the surface of Ni-rich cathode materials, which limits Li transport andmore » reduces their capacities. Furthermore, this study establishes a correlation between the high-rate electrochemical performance of the Ni-based materials and their structural evolution, which can provide profound insights for designing novel cathode materials having both high energy and power densities.« less
  • Core–shell materials have attracted a great deal of interest since core–shell particles have superior physical and chemical properties compared to their single-component counterparts. The cathode material Li(Ni{sub 0.8}Co{sub 0.15}Al{sub 0.05}){sub 0.8}(Ni{sub 0.5}Mn{sub 0.5}){sub 0.2}O{sub 2} (LNCANMO) with a core–shell structure was synthesized via a co-precipitation method and investigated as the cathode material for lithium ion batteries. The core–shell particle consisted of LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} (LNCAO) as the core and LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} as the shell. The cycling behavior between 2.8 and 4.3 V at a current of 0.1 C-rate showed a reversible capacity of ∼195 mAh g{supmore » −1} with little capacity loss after 50 cycles. Extensive assessment of the electronic structures of the LNCAO and LNCANMO cathode materials was carried out using X-ray absorption spectroscopy (XAS). XAS has been used for structure refinement on the transition metal ion of the cathode. In particular, XAS studies of electrochemical reactions have been done from the viewpoint of the transition metal ion. In this study, Ni K-edge XAS spectra of the charge and discharge processes of LNCAO and LNCANMO were investigated.« less