Internal dynamics of blended Li-insertion electrodes

Heubner, Christian; Liebmann, Tobias; Lämmel, C.; Schneider, Michael; Michaelis, Alexander

doi:10.1016/j.est.2018.09.003

Cited by 14 publications

(34 citation statements)

References 39 publications

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“…The latter can be expected to lead to an increased aging of this kind of active material, thus indicating a shortened cycle life of the half-cell. 40 The dependencies described for 0.5C are in the same way qualitatively valid for the discharge rate of 3C (see Figure 8, right). However, the curves of the fraction of the intercalation current appear to be smoothened.…”

Section: Evaluation Of the Numerical Results On The Particle Scalesupporting

confidence: 60%

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Three‐dimensional simulation of transport processes within blended electrodes on the particle scale

et al. 2019

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Summary An electrochemical model that is capable to simulate charge and species transport within the three‐dimensional particulate cathode structure of lithium‐ion battery half‐cells is applied to blended electrodes. The electrodes are assumed to consist of physical mixtures of LiMn2O4 (LMO) and Li[Ni1/3Co1/3Mn1/3]O2 (NMC) as cathode active materials. The results of the numerical simulations reveal that there is a significant temporal variation in the distribution of the intercalation current between the active materials on the particulate level. In this context, the LMO component was found to be electrochemically inactive at the beginning and at the end of a simulated discharge process that leads to the identification of a suitable operating window of the half‐cells between 0.2 < DOD < 0.8. It is shown that within this range, a relaxation of the maximum lithium concentration gradients within the NMC component is achievable. As this provides indications of reduced mechanical stresses within the active material particles, an increased cycling stability of this kind of blended electrodes is expectable. Because of the NMC component's higher volumetric capacity compared with LMO, the separator‐near arrangement of NMC allows the magnitude of ionic current density to be reduced by up to 11% compared with a random particle arrangement. As this indicates a reduction of potential temperature‐induced side reactions of the electrolyte, an increased cycle life of the half‐cells, especially for high‐performance applications, is anticipated. Consequently, multiple‐layer coating processes appear particularly attractive for the production of optimized blended positive electrodes for lithium‐ion batteries.

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Section: Evaluation Of the Numerical Results On The Particle Scalesupporting

confidence: 60%

“…That is because outside of this operating window, the NMC component absorbs a large part of the intercalation current. The latter can be expected to lead to an increased aging of this kind of active material, thus indicating a shortened cycle life of the half‐cell …”

Section: Resultsmentioning

confidence: 99%

Three‐dimensional simulation of transport processes within blended electrodes on the particle scale

et al. 2019

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“…In 2018, Heubner et al . investigated internal dynamics in blended electrodes using a model‐like blend electrode consisting of two separated LFP and LCO electrodes but short‐circuited allowing for the measurement of the “short circuit current” flowing between the two working electrodes (LFP and LCO) during a relaxation step [19] . Mao et al.…”

Section: State‐of‐the‐artmentioning

confidence: 99%

“…(The specific current is related to the mass of LiCoO 2 in the blend). Reproduced from [19] with permission from ELSEVIER…”

Section: State‐of‐the‐artmentioning

confidence: 99%

“…Yet, some meaningful studies have appeared recently, including a review on the electrochemical behaviour of blended electrodes providing meaningful background on the topic. [19] In contrast to conventional electrode with a single type of active material, internal redox processes can take place in blended electrodes. Moreover, changes in the lithium distribution can also be caused by differences in temperature.…”

Section: Introductionmentioning

confidence: 99%

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Blended Positive Electrodes for Li‐Ion Batteries: From Empiricism to Rational Design

Casas‐Cabanas

Ponrouch

2021

Israel Journal of Chemistry

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Physical mixtures (i. e. blends) of two or more active materials are often used in commercial batteries to achieve better performance than what can be attained with a single component. This approach has been empirically driven and found to result in relevant synergistic improvements that are unfortunately poorly understood at a fundamental level. Indeed, internal redox processes (which induce structural changes in the components) can take place in blended electrodes that are severely influenced by electrode kinetics. These are in turn affected by temperature and also electrode formulation. Despite difficulties ahead, efforts to understand such issues are needed to pave the way for a rational electrode design enabling optimized performance which ideally could be tuned to match specific application requirements.

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Understanding Component‐Specific Contributions and Internal Dynamics in Silicon/Graphite Blended Electrodes for High‐Energy Lithium‐Ion Batteries

Heubner

Liebmann

Lohrberg

et al. 2021

Batteries & Supercaps

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Blended electrode materials containing high‐capacity silicon (Si) and robust graphite (Gr) materials are considered advanced alternatives to pure graphite electrodes used in Li‐ion batteries. Understanding the component‐specific lithiation and delithiation behavior and electrochemical interactions between the blended materials is of crucial importance for targeted optimization of composition and microstructural design, yet hardly addressed to date. Herein, a model‐like Si/Gr blended electrode and special electrochemical cell are introduced to directly capture the component specific behaviors for the first time. This includes studies of the formation cycles, the reaction distribution between Si and Gr, the component‐specific contributions to the capacity at different charge and discharge rates, and the internal dynamics during pulse loads and subsequent relaxation. The deconvolution of the components’ behavior during operation provides fundamental insights that contribute to a profound understanding and targeted optimization of Si/Gr blended electrodes. Furthermore, the application of the presented experimental approach can serve scientists to identify and study other advanced materials combinations as blended electrodes for rechargeable batteries.

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Internal dynamics of blended Li-insertion electrodes

Cited by 14 publications

References 39 publications

Three‐dimensional simulation of transport processes within blended electrodes on the particle scale

Three‐dimensional simulation of transport processes within blended electrodes on the particle scale

Blended Positive Electrodes for Li‐Ion Batteries: From Empiricism to Rational Design

Understanding Component‐Specific Contributions and Internal Dynamics in Silicon/Graphite Blended Electrodes for High‐Energy Lithium‐Ion Batteries

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