Cryogenic electron microscopy reveals that applied pressure promotes short circuits in Li batteries

Harrison, Katharine L.; Merrill, Laura; Long, Daniel; Randolph, Steven; Goriparti, Subrahmanyam; Christian, Joseph; Warren, Benjamin; Roberts, Scott Alan; Harris, Stephen J.; Perry, Daniel; Jungjohann, Katherine L.

doi:10.1016/j.isci.2021.103394

Cited by 22 publications

(21 citation statements)

References 72 publications

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“…However, the impacts of applied pressures on the electrochemical performance of Li metal pouch cells are more complex depending on the electrolyte systems and charging-discharging processes. [70,71] Wang et al probed the effect of external pressure on the plating and stripping processes of Li metal anode with Li 7 P 2 S 8 Br 0.5 I 0.5 electrolyte. [67] It was found that the pressure required in the stripping process is positively related to the critical current density (the maximum current density at which dendrite penetration is suppressed), while higher pressure results in lower critical current densities in the plating process (Figure 3e).…”

Section: Pressure Distributionmentioning

confidence: 99%

Working Principles of Lithium Metal Anode in Pouch Cells

Sun

Cheng

et al. 2022

Advanced Energy Materials

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Advanced energy storage technology represented by lithium (Li)-ion batteries (LIBs) has revolutionized human life in recent years. The energy density of LIBs based on intercalation chemistry is approaching its theoretical limit after unremitting efforts for the past three decades. The state-of-the-art LIBs with graphite anode can only achieve an energy density lower than 300 Wh kg −1 . [1] This cannot satisfy the increasing demands for portable electronic devices, electric vehicles, and stationary energy storage systems. [2] Therefore, it is urgently called for next-generation batteries with a high energy density, long lifespan, and high safety performance. [3,4] Electrode material is of great importance in determining the energy density of batteries. [5] As the holy grail anode, Li metal possesses the ultrahigh theoretical specific capacity (3860 mAh g −1 ) and low potential (−3.04 V vs the standard hydrogen electrode). The promising feature renders Li metal anode to be an indispensable candidate for constructing next-generation high-energy-density batteries. [6] A high energy density of 400 or even 500 Wh kg −1 can be achieved with Li metal batteries (LMBs) matching Ni-rich LiNi x Co y Mn (1−x−y) O 2 (0 < x, y <1), oxygen, or sulfur cathodes, etc. [7][8][9] However, the conversion chemistry and high reactivity of Li metal also bring great challenges to the design of robust LMBs with long lifespan and high safety. [10,11] Specifically, Li dendrite growth and infinite volume variation lead to unstable solid electrolyte interphase (SEI) on Li metal anodes, resulting in low Li utilization, capacity decline, and even safety risk, [12] severely hindering the practical applications of LMBs. [13][14][15] Recently, extensive strategies have been exploited to control the dendrite growth of Li metal anodes, including engineering electrolytes and additives, [16] designing 3D host structures, [17][18][19] constructing artificial SEI, [20,21] applying solid-state electrolyte (SSE), [22][23][24] and adjusting operation conditions. [25] A high Coulombic efficiency (>99.9%) and long lifespan (>1000 cycles) have been reported in the materials-level coin cells. [26][27][28] Notably, Li dendrite growth is primarily driven by the kinetical limitation of Li-ion diffusion near the electrolyte/electrode interface. Serious dendrite issues can be encountered under harsh operating conditions in pouch cells, considering the accelerated consumption of Li ions at large currents and high Lithium metal battery has been considered as one of the potential candidates for next-generation energy storage systems. However, the dendrite growth issue in Li anodes results in low practical energy density, short lifespan, and poor safety performance. The strategies in suppressing Li dendrite growth are mostly conducted in materials-level coin cells, while their validity in device-level pouch cells is still under debate. It is imperative to address dendrite issues in pouch cells to realize the practical application of Li metal batteries. This review prese...

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Section: Pressure Distributionmentioning

confidence: 99%

Working Principles of Lithium Metal Anode in Pouch Cells

Sun

Cheng

et al. 2022

Advanced Energy Materials

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“…Meanwhile, the PPC1200 cell with a bare polyethylene (PE) separator experienced a sudden voltage drop at the charge end during the 156 th cycle (Figure c). Recently, Kanamori et al and Harrison et al , demonstrated that although the application of high external pressure (>1 MPa) affords the dense Li deposition, an excess compressive pressure could cause a short circuit, rather than its inhibition, during repeated stripping/plating in Li||Cu cells, thus decreasing the cycle life of Li metal cells. Figure S8 shows that the facile application of a commercially available boehmite dual-coated PE separator improved the stability of the Li metal anode by preventing short circuits.…”

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confidence: 99%

High-Energy-Density, Long-Life Li-Metal Batteries via Application of External Pressure

et al. 2023

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The application of commercially available carbonatebased electrolytes to Li-metal batteries (LMBs) is challenging because of the uncontrollable side reactions of the electrolytes with Li anodes. Herein, a practical carbonate-electrolyte-based LMB with a high areal capacity and long cycle life is proposed. The cycling stability of the proposed LMB is established by applying an external compressive pressure (1200 kPa) and a boehmite-coated separator to prevent the short circuit of the electrodes. The external pressure drives the growth of the Li metal as a dense uniform layer instead of dendrites and mitigates the formation of microcracks in the charged Ni-rich layered cathode. The unprecedented cycling stability of the stacked LMB with a Ni-rich layered cathode, retaining 82.0% of its initial capacity after 500 cycles, can prove instrumental in realizing practical high-energy-density LMBs, thus demonstrating the possibility of employing cell compression to increase the life and energy density of LMBs.

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“…Applied stack pressures on the order of the flow stress of lithium metal can promote interface stability in liquid, 4,10 and solid-state cells, 6 but negative effects of stack pressure have also been noted. 11 At low to moderate plating current densities in liquid cells, the dominant type of filaments are needle-shaped "whiskers," or dense clusters of whiskers termed "moss". This regime of current density is of significant interest for battery applications.…”

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Diffusion and Creep in Lithium Metal Anodes Induced by Plating and Stripping Reactions

Hebert

2023

J. Electrochem. Soc.

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Electrodeposition of lithium on lithium metal negative electrodes (anodes) of liquid cells produces filamentary deposits, resulting in poor cycling efficiency. Experiments suggest that filaments grow by extrusion of metal from the substrate, due to compressive stress introduced during deposition. A model is presented that explores the origin of stress generated in the anode during plating-stripping cycles. According to the model, plating or stripping reactions insert or remove lithium atoms at the interface between the metal and the solid electrolyte interphase (SEI) layer. Stress is induced by the resulting diffusion processes, with diffusion-induced strain accommodated by inelastic creep. Stress distributions during cycling are calculated, and are used in turn to predict curvature transients that would be measured in beam-deflection experiments. The calculations account for the three-dimensional surface morphology, since surface features that protrude above the surface plane do not contribute to curvature changes. Comparisons with recent curvature measurements demonstrate detailed agreement, with diffusion and creep parameters close to literature values. The results support the hypothesis that electrochemical reactions intrinsically generate stress. The model can serve as a framework for analysis of morphogical instability of the lithium anode interface in both liquid and solid-state cells.

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Cryogenic electron microscopy reveals that applied pressure promotes short circuits in Li batteries

Cited by 22 publications

References 72 publications

Working Principles of Lithium Metal Anode in Pouch Cells

Working Principles of Lithium Metal Anode in Pouch Cells

High-Energy-Density, Long-Life Li-Metal Batteries via Application of External Pressure

Diffusion and Creep in Lithium Metal Anodes Induced by Plating and Stripping Reactions

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