Ni–Li anti-site defect induced intragranular cracking in Ni-rich layer-structured cathode

Lin, Qingyun; Guan, Wenhao; Zhou, Jie; Meng, Jie; Huang, Wei; Chen, Tao; Gao, Qiang; Wei, Xiao; Zeng, Yuxuan; Li, Jixue; Zhang, Ze

doi:10.1016/j.nanoen.2020.105021

Cited by 99 publications

(103 citation statements)

References 57 publications

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“…We note that cracks were also observed for single‐crystalline NCM materials when charged to higher potentials. [ 29,30 ] However, oxygen loss and the resulting damage to the crystal structure can impede lithium diffusion and result in fast capacity fading. [ 25 ] We avoid high potentials in the present study as we focus on CAMs cycled in a practical potential window.…”

Section: Resultsmentioning

confidence: 99%

Polycrystalline and Single Crystalline NCM Cathode Materials—Quantifying Particle Cracking, Active Surface Area, and Lithium Diffusion

Trevisanello

Rueß

Conforto

et al. 2021

Advanced Energy Materials

325

219

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Representatives of the LixNi1−y−zCoyMnzO2 (NCM) family of cathode active materials (CAMs) with high nickel content are becoming the CAM of choice for high performance lithium‐ion batteries. In addition to high specific capacities, these layered oxides offer high specific energy, power, and long cycle life. Recently, the development of single crystalline particles of NCM has enabled even longer lifetimes due to achieving higher Coulomb efficiencies. In this work, the performance of NCM materials with different particle size and morphology is explored in terms of key parameters such as the charge‐transfer resistance and the chemical diffusion coefficient of lithium. Cracking of secondary particles leads to liquid electrolyte infiltration in the CAM, lowering the charge‐transfer resistance and increasing the apparent diffusion coefficient by more than one order of magnitude. In contrast, these effects are not observed with single‐crystalline NCM, which is mostly free of cracks after cycling. Consequently, severe kinetic limitations are observed when cycling large “uncracked” secondary particles at low potential and capacity. These results demonstrate that cracking of polycrystalline particles of NCM is not solely detrimental but helps to achieve high reversible capacities and rate capability. Thus, optimization of CAMs size and morphology is decisive to achieve good rate capability with high‐nickel NCMs.

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Section: Resultsmentioning

confidence: 99%

Polycrystalline and Single Crystalline NCM Cathode Materials—Quantifying Particle Cracking, Active Surface Area, and Lithium Diffusion

Trevisanello

Rueß

Conforto

et al. 2021

Advanced Energy Materials

325

219

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“…[17] As interest has moved toward Ni-rich NMC, it has recently been reported that the rapid analysis of raw powders can be capable of resolving defects before operation in NMC622 and NMC811 [18] although minimal particle cracking was observed at this stage in the particles' lifetimes (i.e., before printing into electrode sheets). At the atomic scale, it is thought that the Ni-Li anti-site defects formed during operation may be a precursor for inter-granular cracking within NMC811, [19] and because each primary particle is expected to be a single crystal, or grain, this is also often described as the dislocation of primary particles, that is, the cracking and separation of primary particles. Moreover, when an NMC811 electrode is de-lithiated, the interlayer spacing gradually increases with the cell's state of charge (SoC), before collapsing at high SoC; this is also thought to induce further strain between primary particles within the secondary particle agglomerates.…”

Section: Introductionmentioning

confidence: 99%

Identifying the Origins of Microstructural Defects Such as Cracking within Ni‐Rich NMC811 Cathode Particles for Lithium‐Ion Batteries

Heenan

Wade

Tan

et al. 2020

Advanced Energy Materials

162

141

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The next generation of automotive lithium‐ion batteries may employ NMC811 materials; however, defective particles are of significant interest due to their links to performance loss. Here, it is demonstrated that even before operation, on average, one‐third of NMC811 particles experience some form of defect, increasing in severity near the separator interface. It is determined that defective particles can be detected and quantified using low resolution imaging, presenting a significant improvement for material statistics. Fluorescence and diffraction data reveal that the variation of Mn content within the NMC particles may correlate to crystallographic disordering, indicating that the mobility and dissolution of Mn may be a key aspect of degradation during initial cycling. This, however, does not appear to correlate with the severity of particle cracking, which when analyzed at high spatial resolutions, reveals cracking structures similar to lower Ni content NMC, suggesting that the disconnection and separation of neighboring primary particles may be due to electrochemical expansion/contraction, exacerbated by other factors such as grain orientation that are inherent in such polycrystalline materials. These findings can guide research directions toward mitigating degradation at each respective length‐scale: electrode sheets, secondary and primary particles, and individual crystals, ultimately leading to improved automotive ranges and lifetimes.

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“…Over the last few years, numerous research studies have been targeting the development of Ni-rich cathodes (usually NMC with Ni ratio of 6 or above) to incorporate them in so-called next-generation LIBs [ 5 , 8 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ] for commercial EVs. Most of the experimental and numerical work cited deal with the adversities of high Ni content, namely, chemical and structural instability, both leading to capacity fading, poor rate performance, and potential decay [ 59 ].…”

Section: The Positive Electrode (Cathode)mentioning

confidence: 99%

“…On the other hand, side reactions between electrode and electrolyte increase the thickness of the cathode electrolyte interphase (CEI), which, in turn, decreases ionic conductivity and erodes the surface of the cathodes [ 66 ]. In another study focusing on anti-site defect-induced intragranular cracking [ 61 ], NMC811 cathodes were investigated with scanning transmission electron microscopy and dual-beam-focused ion beam precision. Lattice distortion in Ni-Li regions was identified as a nucleation site for cracks.…”

Section: The Positive Electrode (Cathode)mentioning

confidence: 99%

The Latest Trends in Electric Vehicles Batteries

et al. 2021

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Global energy demand is rapidly increasing due to population and economic growth, especially in large emerging countries, which will account for 90% of energy demand growth to 2035. Electric vehicles (EVs) play a paramount role in the electrification revolution towards the reduction of the carbon footprint. Here, we review all the major trends in Li-ion batteries technologies used in EVs. We conclude that only five types of cathodes are used and that most of the EV companies use Nickel Manganese Cobalt oxide (NMC). Most of the Li-ion batteries anodes are graphite-based. Positive and negative electrodes are reviewed in detail as well as future trends such as the effort to reduce the Cobalt content. The electrolyte is a liquid/gel flammable solvent usually containing a LiFeP6 salt. The electrolyte makes the battery and battery pack unsafe, which drives the research and development to replace the flammable liquid by a solid electrolyte.

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Ni–Li anti-site defect induced intragranular cracking in Ni-rich layer-structured cathode

Cited by 99 publications

References 57 publications

Polycrystalline and Single Crystalline NCM Cathode Materials—Quantifying Particle Cracking, Active Surface Area, and Lithium Diffusion

Polycrystalline and Single Crystalline NCM Cathode Materials—Quantifying Particle Cracking, Active Surface Area, and Lithium Diffusion

Identifying the Origins of Microstructural Defects Such as Cracking within Ni‐Rich NMC811 Cathode Particles for Lithium‐Ion Batteries

The Latest Trends in Electric Vehicles Batteries

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