Failure mode of thick cathodes for Li-ion batteries: Variation of state-of-charge along the electrode thickness direction

Kim, Hanseul; Oh, Seung Kyo; Lee, Jeonghyeop; Doo, Sung Wook; Kim, Young‐Jin; Lee, Kyu‐Tae

doi:10.1016/j.electacta.2021.137743

Cited by 38 publications

(25 citation statements)

References 29 publications

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“…16,17 This would lead to locally high current densities and nonuniform reaction kinetics. 18,19 As shown in Figure 1a, during the discharging process, a concentration gradient becomes more obvious at higher rates or with a thicker electrode. The Li + insertion begins at the cathode surface at the separator side and progresses to the current collector side (Figure 1b).…”

Section: Introductionmentioning

confidence: 99%

“…Although low-tortuosity electrode design proves effective in promoting charge transport kinetics, heterogeneous electrochemical mass transport along the depth direction is inevitable in thick electrodes, especially at high rates. , This would lead to locally high current densities and nonuniform reaction kinetics. , As shown in Figure a, during the discharging process, a concentration gradient becomes more obvious at higher rates or with a thicker electrode. The Li + insertion begins at the cathode surface at the separator side and progresses to the current collector side (Figure b).…”

Section: Introductionmentioning

confidence: 99%

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Low-Tortuosity Thick Electrodes with Active Materials Gradient Design for Enhanced Energy Storage

Zhang

et al. 2022

ACS Nano

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The ever-growing energy demand of modern society calls for the development of high-loading and high-energy-density batteries, and substantial research efforts are required to optimize electrode microstructures for improved energy storage. Low-tortuosity architecture proves effective in promoting charge transport kinetics in thick electrodes; however, heterogeneous electrochemical mass transport along the depth direction is inevitable, especially at high C-rates. In this work, we create an active material gradient in low-tortuosity electrodes along iontransport direction to compensate for uneven reaction kinetics and the nonuniform lithiation/delithiation process in thick electrodes. The gradual decrease of active material concentration from the separator to the current collector reduces the integrated ion diffusion distance and accelerates the electrochemical reaction kinetics, leading to improved rate capabilities. The structure advantages combining low-tortuosity pores and active material gradient offer high mass loading (60 mg cm −2 ) and enhanced performance. Comprehensive understanding of the effect of active material gradient architecture on electrode kinetics has been elucidated by electrochemical characterization and simulations, which can be useful for development of batteries with high-energy/power densities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low-Tortuosity Thick Electrodes with Active Materials Gradient Design for Enhanced Energy Storage

Zhang

et al. 2022

ACS Nano

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“…Similarly, Kim et al created a reduced pore-size gradient along the electrode thickness from the separator side to the current collector by placing larger AM particles in the upper layer while smaller ones in the lower layer. [43] The large pore size on the top prevents pore-clogging during cycling and continual increase of R ion , which, in turn, suppresses the uneven SOC distribution along the thickness direction of the electrode, leading to an improved initial capacity and cycling stability of thick electrodes.…”

Section: Gradient Pore Structurementioning

confidence: 99%

Gradient Design for High‐Energy and High‐Power Batteries

Zhang

et al. 2022

Advanced Materials

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lithium-ion batteries (LIBs) with intercalation-type cathodes, liquid electrolytes, and graphite anodes are approaching the energy-density limits; therefore, exploring new redox chemistries or battery configurations is needed to improve the performance of batteries. [3] On the one hand, high-capacity active materials (AMs) such as sulfur-or Li-rich cathodes are extensively explored to offer new chemistries for higher theoretical capacities. [4,5] On the other, increasing efforts are being made to optimize the microstructures of the cathode, anode, and electrolyte to improve the charge-transport kinetics and cell-level energy/power density. [6,7] Charge transport in batteries includes metal-ion transport in the electrolyte, charge transfer at the electrolyte/electrode interphase, solidstate diffusion inside the electrode, and electron transport along the conductive pathways. [8,9] At a low current density, the charge-transfer process dominates the electrochemical kinetics. As current density increases, ion diffusion in the electrolyte plays a major role. [10] Ion transport in the electrolyte is determined by the porous structure of the electrodes and separators. [11,12] In LIBs with a liquid electrolyte, ion diffusion in the porous electrodes is the rate-limiting process. The typical LIB electrodes are isotropic at the macroscale structure, made of a homogeneous mixture of AMs, conductive agents, binders, interconnected pores, etc. The limited ion mobility in the tortuous pores and the anisotropic electric field during operation inevitably cause heterogeneous mass transport through the thickness direction of the electrode. [13] Due to concentration gradients, the reaction kinetics can be different at different depths, and not all the AMs are accessed and activated at the same time. [14,15] The disparity in charge-transport dynamics and reaction kinetics results in underuse of the AMs and reaction polarization, especially at high C-rates, and at a certain C-rate, reaction polarization increases proportionally with electrode thickness due to the lengthened diffusion pathway. [16] Therefore, it is critical to design electrodes with a rational architecture to regulate charge transport. In particular, constructing electrodes with varying microstructures or compositions along the depth direction would allow us to reduce increasing resistances along the charge-transport direction and thus compensate the reaction polarization, which supports high energy and fast charging capacity.The lithium (Li)-metal anode, with the highest gravimetric energy density of 3860 mAh g −1 and the lowest redox potential (−3.04 V vs the standard hydrogen electrode), is considered the Charge transport is a key process that dominates battery performance, and the microstructures of the cathode, anode, and electrolyte play a central role in guiding ion and/or electron transport inside the battery. Rational design of key battery components with varying microstructure along the charge-transport direction to realize optimal local charge-transport dyn...

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“…Such restrictions are amplified at high C-rates, and the composite electrode might experience spatially varying damage. In thick electrodes, Li concentration and reaction heterogeneity can be diminished by incorporating a particle size gradient across the thickness . Stacking smaller particles toward the current collector can make them more efficiently utilized because of their longer Li + diffusion length.…”

Section: Origin Of Chemomechanical Degradationmentioning

confidence: 99%

Chemomechanics of Rechargeable Batteries: Status, Theories, and Perspectives

Vasconcelos

et al. 2022

Chem. Rev.

109

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Chemomechanics is an old subject, yet its importance has been revived in rechargeable batteries where the mechanical energy and damage associated with redox reactions can significantly affect both the thermodynamics and rates of key electrochemical processes. Thanks to the push for clean energy and advances in characterization capabilities, significant research efforts in the last two decades have brought about a leap forward in understanding the intricate chemomechanical interactions regulating battery performance. Going forward, it is necessary to consolidate scattered ideas in the literature into a structured framework for future efforts across multidisciplinary fields. This review sets out to distill and structure what the authors consider to be significant recent developments on the study of chemomechanics of rechargeable batteries in a concise and accessible format to the audiences of different backgrounds in electrochemistry, materials, and mechanics. Importantly, we review the significance of chemomechanics in the context of battery performance, as well as its mechanistic understanding by combining electrochemical, materials, and mechanical perspectives. We discuss the coupling between the elements of electrochemistry and mechanics, key experimental and modeling tools from the small to large scales, and design considerations. Lastly, we provide our perspective on ongoing challenges and opportunities ranging from quantifying mechanical degradation in batteries to manufacturing battery materials and developing cyclic protocols to improve the mechanical resilience.

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Failure mode of thick cathodes for Li-ion batteries: Variation of state-of-charge along the electrode thickness direction

Cited by 38 publications

References 29 publications

Low-Tortuosity Thick Electrodes with Active Materials Gradient Design for Enhanced Energy Storage

Low-Tortuosity Thick Electrodes with Active Materials Gradient Design for Enhanced Energy Storage

Gradient Design for High‐Energy and High‐Power Batteries

Chemomechanics of Rechargeable Batteries: Status, Theories, and Perspectives

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