SEARCH · Search NASA
Results for “pouch cell”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Reaction heterogeneity in practical high-energy lithium–sulfur pouch cells
The lithium–sulfur (Li–S) battery is a promising next-generation energy storage technology because of its high theoretical energy and low cost. Extensive research efforts have been made on new materials and advanced characterization techniques for mechanistic studies. However, it is uncertain how discoveries made on the material level apply to realistic batteries due to limited analysis and characterization of real high-energy cells, such as pouch cells. Evaluation of pouch cells (>1 A h) (instead of coin cells) that are scalable to practical cells provides a critical understanding of current limitations which enables the proposal of strategies and solutions for further performance improvement. Herein, we design and fabricate pouch cells over 300 W h kg -1 , compare the cell parameters required for high-energy pouch cells, and investigate the reaction processes and their correlation to cell cycling behavior and failure mechanisms. Spatially resolved characterization techniques and fluid-flow simulation reveal the impacts of the liquid electrolyte diffusion within the pouch cells. We found that catastrophic failure of high-energy Li–S pouch cells results from uneven sulfur/polysulfide reactions and electrolyte depletion for the first tens of cycles, rather than sulfur dissolution as commonly reported in the literature. The uneven reaction stems from limited electrolyte diffusion through the porous channels into the central part of thick cathodes during cycling, which is amplified both across the sulfur electrodes and within the same electrode plane. A combination of strategies is suggested to increase sulfur utilization, improve nanoarchitectures for electrolyte diffusion and reduce consumption of the electrolytes and additives.
High-Energy Lateral Mapping (HELM) Studies of Inhomogeneity and Failure Mechanisms in NMC622/Li Pouch Cells
Explore the source record for details and available documents.
Lithium loss, resistance growth, electrode expansion, gas evolution, and Li plating: Analyzing performance and failure of commercial large-format NMC-Gr lithium-ion pouch cells
Not Available
Safety and Long-Term Performance of Lithium-ion Pouch Cells
Lithium-ion batteries have the highest energy density of the batteries available in the commercial market today. Although most lithium-ion cell designs use a metal can design, this has changed significantly in recent years. Cell designs are offered in the pouch format as they offer better volumetric and gravimetric energy densities and in some cases, higher tolerance to abuse or off-nominal conditions. In the past decade, several state-of-the-art lithium-ion pouch cell designs have been tested. The pouch cell designs have become more robust in the past two years but there are still a few issues that need to be looked into for optimization. The pouch cells seem to have a tendency to swell when left in storage under ambient conditions. The cells also swell under overvoltage and undervoltage conditions. A significant issue that has been observed is the swelling of the cells under a vacuum condition which could lead to deformation of the cell pouch after this exposure. This last factor would be very critical in the use of these cell designs for space applications as vacuum exposure is used to check for cell and battery leaks before it is flown into space. In rare cases, corrosion of the aluminum layer of the pouches has been observed in stored cells. Pouch material analysis has been carried out in an effort to understand the strength of the pouches and determine if this is a factor in the corrosion as well as unsafe condition of the cells as deformation of the inner layers of the pouch could occur when the cells swell under the various conditions described above. Pouch materials are typically aluminized plastic, made up of a layer of Al sandwiched between one or more layers of polymeric material. Deformations or cell manufacturing processes could lead to a compromise of the inner polymeric layer/s of the pouch leading to the corrosion of the Al layer in the aluminized pouch material. The safety of the pouch cell designs has been determined for cells from various manufacturers. The results are varied and in some cases, unexpected. This paper presents a summary of the tests carried out on a few li-ion pouch cell designs from various cell manufacturers. The data will include performance under different conditions specifically cycling under vacuum conditions with and without restraints as well as safety test data. The presentation will also include detailed analysis of the pouch material for the cells studied.
Unlocking Failure Mechanisms and Improvement of Practical Li–S Pouch Cells through In Operando Pressure Study
For Lithium-sulfur (Li-S) battery commercialization, the study at a pouch cell level is essential, as some problems ignored or deemed minimal at the smaller level could have a greater effect on the performance of the larger pouch cell. Herein, the failure mechanisms of Li-S pouch cells are deeply investigated via in operando pressure analysis. It is found that highly porous structures of cathodes/separators and slow electrolyte diffusion through cathodes/separators can both lead to poor initial wetting. Additionally, Li-metal anode dominates the thickness variation of the whole pouch cell, which is verified by in situ measured pressure variation. Consequently, a real-time approach that combined normalized pressure with dP/dV analysis is proposed and validated to diagnose the morphology evolution of Li-metal anode. Moreover, applied pressure and porosity/tortuosity ratio of the cathode are both identified as independent factors that influence anode performance. In addition to stabilizing anodes, high pressure is proven to improve the cathode connectivity and avoid cathode cracking over cycling, which improves the possibility of developing cathodes with high sulfur mass loading. Here, this work provides insights into Li-S pouch cell design (e.g., cathode and separator) and highlights pathways to improve cell capacity and cycling performance with applied and monitored pressure.
Unlocking Failure Mechanisms and Improvement of Practical Li-S Pouch Cells Through in Operando Pressure Study
For Lithium-sulfur (Li-S) battery commercialization, the study at a pouch cell level is essential, as some problems ignored or deemed minimal at the smaller level could have a greater effect on the performance of the larger pouch cell. Herein, the failure mechanisms of Li-S pouch cells are deeply investigated via in operando pressure analysis. It is found that highly porous structures of cathodes/separators and slow electrolyte diffusion through cathodes/separators can both lead to poor initial wetting. Additionally, Li-metal anode dominates the thickness variation of the whole pouch cell, which is verified by in situ measured pressure variation. Consequently, a real-time approach that combined normalized pressure with dP/dV analysis is proposed and validated to diagnose the morphology evolution of Li-metal anode. Moreover, applied pressure and porosity/tortuosity ratio of the cathode are both identified as independent factors that influence anode performance. In addition to stabilizing anodes, high pressure is proven to improve the cathode connectivity and avoid cathode cracking over cycling, which improves the possibility of developing cathodes with high sulfur mass loading. This work provides insights into Li-S pouch cell design (e.g., cathode and separator) and highlights pathways to improve cell capacity and cycling performance with applied and monitored pressure
Pressure effects on lithium anode/nickel-manganese-cobalt oxide cathode pouch cells through fixture design
Applying external pressure to a pouch cell results in improved performance, implicating systems-level design of batteries. Here, different formats and amounts of external pressure to Li-Li x Ni 0.8 Mn 0.1 Co 0.1 O 2 (Li-NMC811) pouch cells were studied under lean electrolyte conditions. Due to the more uniform lithium plating/stripping, a constant gap fixture that retains the distance of the frame during cycling performed greater than a constant pressure fixture that retains applied pressure to the cell. In addition, the use of flexible foam in a constant gap fixture revealed enhanced cycle life at 10 psi; however, at 30 psi, the use of a rigid plate extended cycle life to over 250 cycles, while the foam severely shortened cycle life. This discrepancy with pressure was proven to be driven by stress distribution on cell components. The failure mechanisms and the effects of pressure fixture design on cell components were unveiled, shedding light on improving high-energy battery performance through at-scale fixture design.
Lithium metal pouch cells and methods of making the same
A lithium metal pouch cell having a specific energy ≥300 Wh·kg−1 includes an anode comprising lithium metal and an anode current collector, the anode having an areal capacity N (mAh·cm −2 ); a cathode comprising a cathode material and a cathode current collector, the cathode having an a real capacity P (mAh·cm −2 ), wherein a ratio of N/P is within a range of 0.02 to 5; an electrolyte having an electrolyte mass E and comprising a lithium active salt and a solvent, the lithium metal pouch cell having an electrolyte mass to cell capacity (E/C) ratio within a range of 1 to 6 g·Ah −1 ; a separator positioned between the anode and the cathode; and a packaging material defining a pouch enclosing the anode, cathode, electrolyte, and separator; wherein a protruding tab of the anode current collector and a protruding tab of the cathode current collector are external to the pouch.
Lithium metal pouch cells and methods of making the same
A lithium metal pouch cell having a specific energy ≥300 Wh·kg -1 includes an anode comprising lithium metal and an anode current collector, the anode having an areal capacity N (mAh·cm −2 ); a cathode comprising a cathode material and a cathode current collector, the cathode having an a real capacity P (mAh·cm −2 ), wherein a ratio of N/P is within a range of 0.02 to 5; an electrolyte having an electrolyte mass E and comprising a lithium active salt and a solvent, the lithium metal pouch cell having an electrolyte mass to cell capacity (E/C) ratio within a range of 1 to 6 g·Ah −1 ; a separator positioned between the anode and the cathode; and a packaging material defining a pouch enclosing the anode, cathode, electrolyte, and separator; wherein a protruding tab of the anode current collector and a protruding tab of the cathode current collector are external to the pouch.
Progress and Prospects of Inorganic Solid-State Electrolyte-Based All-Solid-State Pouch Cells
Here, all-solid-state batteries have piqued global research interest because of their unprecedented safety and high energy density. Significant advances have been made in achieving high room-temperature ionic conductivity and good air stability of solid-state electrolytes (SSEs), mitigating the challenges at the electrode–electrolyte interface, and developing feasible manufacturing processes. Along with the advances in fundamental study, all-solid-state pouch cells using inorganic SSEs have been widely demonstrated, revealing their immense potential for industrialization. This review provides an overview of inorganic all-solid-state pouch cells, focusing on ultrathin SSE membranes, sheet-type thick solid-state electrodes, and bipolar stacking. Moreover, several critical parameters directly influencing the energy density of all-solid-state Li-ion and lithium–sulfur pouch cells are outlined. Finally, perspectives on all-solid-state pouch cells are provided and specific metrics to meet certain energy density targets are specified. This review looks to facilitate the development of inorganic all-solid-state pouch cells with high energy density and excellent safety.
Unveiling the Thermal Stability of Sodium Ion Pouch Cells Using Accelerating Rate Calorimetry
The thermal stability of ~420 mAh Na 0.97 Ca 0.03 [Mn 0.39 Fe 0.31 Ni 0.22 Zn 0.08 ]O 2 (NCMFNZO)/hard carbon (HC) pouch cells was investigated using accelerating rate calorimetry (ARC) at elevated temperatures. 1 m NaPF 6 in propylene carbonate (PC):ethyl methyl carbonate (EMC) (1:1 by volume) was used as a control electrolyte. Adding 2 wt% fluoroethylene carbonate to the electrolyte improves the cell's thermal stability by decreasing the self-heating rate (SHR) across the whole testing temperature range. The selected states-of-charge (SoC), including 70%, 84%, and 100%, exhibit minimal impact on the exothermic behavior, except for a slight decrease in SHR after ~275 °C at 70% SoC. When compared to traditional lithium-ion batteries operating at 100% SoC, NCMFNZO/HC pouch cells demonstrate inferior thermal stability compared to LiFePO 4 (LFP)/graphite pouch cells, displaying a higher SHR from 220 to 300 °C. LiNi 0.8 Mn 0.1 Co 0.1 O 2 /graphite + SiO x pouch cells exhibit the worst safety performance, with an early onset temperature of ~100 °C and the highest SHR across the entire temperature range. These results offer a direct comparison of the impact of SoC and electrolyte compositions on the thermal stability of SIBs at elevated temperatures, highlighting that there is still room for improvement in SIBs safety performance compared to LFP/graphite chemistry.
In situ visualization of multicomponents coevolution in a battery pouch cell
Lithium-ion battery (LIB) is a broadly adopted technology for energy storage. With increasing demands to improve the rate capability, cyclability, energy density, safety, and cost efficiency, it is crucial to establish an in-depth understanding of the detailed structural evolution and cell-degradation mechanisms during battery operation. Here, we present a laboratory-based high-resolution and high-throughput X-ray micro–computed laminography approach, which is capable of in situ visualizing of an industry-relevant lithium-ion (Li-ion) pouch cell with superior detection fidelity, resolution, and reliability. This technique enables imaging of the pouch cell at a spatial resolution of 0.5 μm in a laboratory system and permits the identification of submicron features within cathode and anode electrodes. We also demonstrate direct visualization of the lithium plating in the imaged pouch cell, which is an important phenomenon relevant to battery fast charging and low-temperature cycling. Our development presents an avenue toward a thorough understanding of the correlation among multiscale structures, chemomechanical degradation, and electrochemical behavior of industry-scale battery pouch cells.
A high-energy and long-cycling lithium–sulfur pouch cell via a macroporous catalytic cathode with double-end binding sites
Lithium-sulfur batteries are attractive alternatives to lithium-ion batteries because of their high theoretical specific energy and natural abundance of sulfur. However, the practical specific energy and cycle life of Li-S pouch cells are significantly limited by the use of thin sulfur electrodes/flooded electrolytes and polysulfides shuttle/Li metal degradation, respectively. In this work we propose a cathode design concept to achieve good Li-S pouch cell performances. The cathode is composed of uniformly embedded ZnS nanoparticles and Co-N-C single-atom catalyst to form double-end biding sites inside a highly oriented macroporous host, which can effectively immobilize and catalytically convert polysulfides intermediates during cycling, thus eliminating the shuttle effect and lithium metal corrosion. The ordered macropores enhance ionic transport under high sulfur loading by forming sufficient catalyst/conductive support/electrolyte triple-phase boundaries. This prevents the formation of inactive sulfur (dead sulfur). Our cathode structure shows improved performances in a pouch cell configuration under high sulfur loading and lean electrolyte operation. An Ah-level pouch cell with only 100% lithium excess can deliver a cell specific energy of > 300 Wh kg –1 with a Coulombic efficiency >95% for 80 cycles.
X-ray Micro-Computed Tomography for Structural Analysis of All-Solid-State Battery at Pouch Cell Level
Characterizing the microstructure of all-solid-state batteries (ASSBs) during fabrication and operation is vital for their advancement, particularly as scaling to pouch cell levels introduces challenges in probing large-scale microstructural evolution. This work highlights the potential of synchrotron X-ray micro-computed tomography (sXCT) as a nondestructive, rapid (<30 min), and high-resolution technique for visualizing and quantifying key microstructural features, including overhang, porosity, contact loss, active surface area, and tortuosity, in all-solid-state pouch cells. The large field of view (up to millimeters) of sXCT enables detailed analysis at an industry-relevant scale, bridging the gap between laboratory research and commercial applications. Furthermore, integrating realistic sXCT-derived 3D models into multiphysics simulations could provide insights into chemo-mechanical degradation, particularly at the edges of the pouch cells, offering a pathway for designing robust, high-performance ASSBs. This perspective establishes sXCT as an indispensable tool for advancing both the understanding and the engineering of next-generation energy storage systems.
Controlled large-area lithium deposition to reduce swelling of high-energy lithium metal pouch cells in liquid electrolytes
Lithium (Li) metal battery technology, renowned for its high energy density, faces practical challenges, particularly concerning large volume change and cell swelling. Despite the profound impact of external pressure on cell performance, there is a notable gap in research regarding the interplay between external pressure and the electroplating behaviours of Li+ in large-format pouch cells. Here we delve into the impact of externally applied pressure on electroplating and stripping of Li in 350 Wh kg –1 pouch cells. Employing a hybrid design, we monitor and quantify self-generated pressures, correlating them with observed charge–discharge processes. A two-stage cycling process is proposed, revealing controlled pouch cell swelling of less than 10%, comparable to state-of-the-art Li-ion batteries. Finally, the pressure distribution across the cell surface unveils a complex Li+ detour behaviour during electroplating, highlighting the need for innovative strategies to address uneven Li plating and enhance Li metal battery technology.
Stress evolution and thickness change of a lithium-ion pouch cell under various cycling conditions
We report to design large-sized lithium-ion battery modules for the application of electric vehicles and grid-level energy storage, it is of important significance to understand how stress and dimension of a single pouch cell fluctuate during charge/discharge cycles. In this study, stress evolution under the constant-thickness condition and thickness change under the constant-stress condition are measured for in-house fabricated pouch cells, respectively. The results of stress measurements show that the stress increase percentage generally decreases when the charge/discharge current increases, regardless of the value of the initial compressive stress. With the same current density, the stress increase percentage generally increases when the upper cutoff voltage increases. With the same current density and upper cutoff voltage, the stress increase percentage decreases when the initial compressive stress increases. The results of thickness measurements show that the volume expansion percentage generally increases when the current density increases, regardless of the value of the constant compressive stress. With the same current density, the volume expansion percentage generally increases when the upper cutoff voltage increases. With the same current density and upper cutoff voltage, the volume expansion decreases when the constant compressive stress increases. The results provide important insights into the design principles of battery packs.
Insight into the deformation features and capacity loss mechanisms of lithium-ion pouch cells under spherical indentation conditions
Mechanical deformation under extreme conditions is one of the important reasons for the failure of lithium-ion batteries in automotive application. However, the deformation features and component failure of lithium-ion cells to external loading has never been a design consideration. Here, in this study, we conduct spherical indentation tests on a dozen of lithium-ion cells with different capacities under different control mode conditions to investigate their deformation features and capacity loss mechanisms. The experimental results show that, under mechanical deformation conditions, internal faults of cells occur in stages, and energy accumulation and sudden release are two key processes of cell's mechanical failure. The cells' state of charge is the main factor affecting their thermal runaway behaviors. In addition, a finite element model is developed to simulate the deformation features and the failure mechanism of key components of lithium-ion pouch cells; the 3D x-ray computed tomography is employed to demonstrate its internal configuration. With this model, the force-strain response, the deformation features as well as the size of the failure area of lithium-ion cells under spherical indentation conditions are accurately predicted. In 3D x-ray computed tomography images, unique mud cracks in cooper current collector are observed, and the influence mechanisms of the isolated fragments on the cell capacities are revealed. These results may provide useful information for the mechanical structure design of the components of lithium-ion pouch cells.