Interfacial Chemistry of Liquid Metals in Lithium-Ion Batteries

ECS Meeting Abstracts · 2025-11-24

Gallium-based liquid metals (GLMs) are promising anode materials for lithium-ion batteries due to their low-melting point, fluidity, high-electrical and -thermal conductivity, and high-theoretical capacity for Li (769 mAh/g, Li 2 Ga). Notably, GLMs undergo a reversible liquid-to-solid-to-liquid transition during lithiation and delithiation, enabling a self-healing mechanism that mitigates surface defects. This mechanism extends the cycle life of anodes utilizing GLMs either as active materials ( 1–6 ) or in combination with high-volume expansion materials such as silicon (~400%) ( 7–9 ) . Fundamental studies on the self-healing mechanism of GLMs are limited. Previous investigations have primarily relied on macroscopic characterizations such as X-ray diffraction (XRD) in bulk electrodes ( 3,10 ) or in situ transmission electron microscopy (TEM) on individual GLM nanoparticles (NPs) in solid-state cells open to the environment ( 6,11 ) . In this work, we adopt a multi-scale approach to gain insights into the (de)lithiation mechanism. We conducted: (1) in situ TEM observations of GLM NPs on a TEM grid current collector to simultaneously track lithiation/delithiation dynamics across multiple nanoparticles; (2) cryogenic TEM where GLM NPs on a TEM grid are cycled in a lithium-ion battery electrolyte, and the grid is subsequently transferred to a cryo-TEM for high-resolution interfacial characterization of the GLM NPs; and (3) cryogenic focused-ion beam tomography to analyze structural changes in a composite electrode comprised of GLM NPs, Super P carbon, and PVDF binder on a Cu current collector over continuous cycles within a coin or pouch cell. By investigating GLMs at multiple length scales, this study advances the understanding of how the lithiation/delithiation mechanism of GLM NPs influences capacity fade in lithium-ion batteries. In a broader context, this study establishes a framework for future multi-length scale investigations into battery materials. References Jin, X. et al. Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes. Adv. Mater. 34 , 2200181 (2022). Zhu, M., Li, S., Li, B. & Yang, S. A liquid metal-based self-adaptive sulfur–gallium composite for long-cycling lithium–sulfur batteries. Nanoscale 11 , 412–417 (2019). Guo, X. et al. A Self-Healing Room-Temperature Liquid-Metal Anode for Alkali-Ion Batteries. Adv. Funct. Mater. 28 , 1804649 (2018). Pu, J. et al. Liquid Metal-Based Stable and Stretchable Zn-Ion Battery for Electronic Textiles. Adv. Mater. 36 , 2305812 (2024). Liu, G. et al. Soft, Highly Elastic, and Discharge-Current-Controllable Eutectic Gallium–Indium Liquid Metal–Air Battery Operated at Room Temperature. Adv. Energy Mater. 8 , 1703652 (2018). Huang, C. et al. Alkali-ion Batteries by Carbon Encapsulation of Liquid Metal Anode. Adv. Mater. n/a , 2309732. Hapuarachchi, S. N. S. et al. Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium-Ion Batteries. Batter. Supercaps 1 , 122–128 (2018). Ju, Z. et al. Assembled MXene–Liquid Metal Cages on Silicon Microparticles as Self-Healing Battery Anodes. Nano Lett. 24 , 6610–6616 (2024). Zhao, Z. et al. Liquid Metal Remedies Silicon Microparticulates Toward Highly Stable and Superior Volumetric Lithium Storage. Adv. Energy Mater. 12 , 2103565 (2022). Wang, K. et al. Core-shell GaSn@rGO nanoparticles as high-performance cathodes for room-temperature liquid metal batteries. Scr. Mater. 217 , 114792 (2022). Liang, W. et al. Nanovoid Formation and Annihilation in Gallium Nanodroplets under Lithiation–Delithiation Cycling. Nano Lett. 13 , 5212–5217 (2013).

A Contiguous Interlayer/Separator System to Enable Low-Capacity Fade Lithium-Sulfur Batteries

ECS Meeting Abstracts · 2025-11-24

The demand for sustainable energy solutions, electric vehicles, and portable electronics is driving the development of high-energy-density, low-cost energy storage technologies. Lithium–sulfur (Li–S) batteries are a promising candidate for next-generation energy storage systems due to their high theoretical energy densities and charge capacities, surpassing conventional lithium-ion (Li-ion) batteries. The transition-metal oxide cathodes used in Li-ion batteries have a capacity limit of about 250 mAh/g, while sulfur boasts a theoretical capacity of around 1672 mAh/g 1 . Additionally, sulfur's natural abundance and lower environmental impact 2 make Li-S batteries a promising alternative. However, their commercialization is hindered by the “polysulfide shuttle effect,” wherein elemental sulfur (S₈) undergoes stepwise electrochemical reduction during discharge to form soluble lithium polysulfides (LiPSs). These intermediates migrate to the lithium anode, resulting in active material loss and severe capacity fading. A promising strategy to mitigate this issue is to incorporate a functional interlayer that acts as a physical and chemical barrier between the cathode and separator, trapping polysulfides and stabilizing redox reactions 3 . In this study, we introduce a multifunctional composite interlayer comprised of poly(vinylidene difluoride)-based soft dendritic colloids (PVDF-SDCs) in combination with carbon nanotubes (CNTs). The PVDF-SDCs were prepared using a turbulent solvent–nonsolvent induced phase-separation method, which yields a highly porous, fibrous morphology with unique adhesive properties. These features enabled the fabrication of two distinct interlayer configurations: a freestanding CNT/PVDF-SDC interlayer (~ 40-μm thick), and a direct-deposited CNT/PVDF-SDC@Celgard interlayer (~ 20-μm thick). Both interlayers were fabricated using shear-driven nanofabrication followed by vacuum-filtration, forming uniform and flexible membranes. The CNT/PVDF-SDC interlayer, with a surface area of 103 m² g⁻¹, exhibits multiscale porosity (ranging from nanometers to microns). These aspects, along with their capacity to provide electronic pathways, promote effective LiPS entrapment, ion/electron transport, and accommodation of volume expansion. Compared to interlayer-free cells, both interlayer designs improved electrochemical performance. The freestanding interlayer achieved an initial capacity of ~1190 mAh g⁻¹ and retained 74% capacity after 400 cycles at 0.2 C. When evaluated at a higher rate of 1 C, the cell maintained ~900 mAh/g with 67% capacity retention over 400 cycles. The CNT/PVDF-SDC@Celgard interlayer demonstrated comparable initial capacity but with greater capacity fade over extended cycling, likely due to its thinner structure and reduced LiPS adsorption capacity. Nonetheless, its integrated design resulted in lower interfacial resistance and improved rate capability due to better physical contact with the separator. Under high-sulfur loading (4 mg cm⁻²) and moderate electrolyte conditions (E/S = 8 μL mg⁻¹), the FS-CNT/PVDF-SDC interlayer delivered an areal capacity of ~ 4.9 mAh cm⁻² and retained 55% after 250 cycles. To validate the robustness of this design, multi-cell tests were conducted under identical conditions ( 4 mg S cm -2 , e/S=8 μL mg⁻¹,0.2C) . The cells displayed overlapping cycling trends and Coulombic efficiencies above 95%, confirming reproducibility and repeatability of the interlayer fabrication process. 1 Manthiram, A.; Fu, Y.; Chung S.-H.; Zu,C.; Su, Y.-S. Rechargeable Lithium-Sulfur Batteries. Chem. Rev. 2014, 114 (23), 11751-11787. https://doi.org/10.1021/cr5000062v. 2 Shen, Z.; Jin, X.; Tian, J.; Li, M.; Yuan, Y.; Zhang, S.; Fang, S.; Fan, X.; Xu, W.; Lu, H.; Lu, J.; and Zhang, H. Cation-Doped ZnS Catalysts for Polysulfide Conversion in Lithium-Sulfur Batteries, Nat. Catal., 2022, 5, 555–563. https://doi.org/10.1038/s41929-022-00804-4 3 Huang, Y.; Lin, L.; Zhang, C.; Liu, L.; Li, Y.; Qiao, Z.; Lin, J.; Wei, Q.; Wang, L.; Xie, Q.; Peng, D.-L. Recent Advances and Strategies toward Polysulfides Shuttle Inhibition for High-Performance Li-S Batteries, Adv. Sci. 2022, 9 (12), 2106004. https://doi.org/10.1002/advs.202106004.

High-Mass-Loading Sulfur Cathodes via Soft Dendritic Colloid Networks Integrated with a MXene Current Collector

ECS Meeting Abstracts · 2025-11-24

Developing structurally stable, high-sulfur loading cathodes remains a key challenge in advancing flexible and durable lithium-sulfur (Li-S) battery systems. Here, we report a novel and efficient cathode fabrication strategy based on a Soft Dendritic Colloid (SDC) network, enabling the formation of high-sulfur-mass-loading, crack-free, and flexible cathode structures with a tunable, tortuous architecture. The hierarchical network structure effectively traps polysulfides within the cathode matrix and accommodates volume expansion during cycling. The shear-driven assembly of polymeric colloids serves as both mechanical support and a dispersive medium, overcoming limitations of conventional slurry-cast electrodes—such as binder detachment, poor homogeneity, and structural failure under high loading. Sulfur is introduced via melt diffusion into carbon nanotubes (S/CNT), followed by uniform integration into the PVDF–SDC matrix using high-shear mixing to form a freestanding, binder-free composite cathode. The unique SDC-derived “fishnet” morphology spans nano- to microscale pores, offering excellent tortuosity that not only improves electrolyte accessibility but also anchors polysulfides and accommodates volumetric changes during charge–discharge processes. This architecture allows for precise control of active material distribution and electrode thickness, supporting sulfur loadings up to 10 mg cm⁻² without structural failure. To further enhance the electrical conductivity and reduce inactive mass from conventional metal current collectors, a 5-µm-thick Ti 3 C 2 T x MXene film is deposited onto the cathode surface via vacuum filtration. This MXene layer functions as both a lightweight current collector and a catalytically active interface, accelerating polysulfide conversion, reducing polarization, and improving redox kinetics. The resulting bilayer cathode is flexible, foldable, and mechanically robust, with uniform electrolyte penetration, efficient sulfur utilization, and resistance to cracking or delamination—while partially anchoring polysulfides and accommodating volume expansion. The integrated MX-S/CNT/PVDF-SDC cathode achieves an initial specific capacity of 1075 mAh g⁻¹, retains 76% capacity after 200 cycles at 0.1 C, and delivers an areal capacity of 6.6 mAh cm⁻² at a sulfur loading of 5.5 mg cm⁻². Even at a high sulfur mass loading of 8.6 mg cm⁻², the cell maintains a discharge capacity of 972 mAh g⁻¹ and delivers an areal capacity of 8.2 mAh cm⁻² at 0.2 C over 100 cycles at 25 °C. By eliminating metal foils and simplifying fabrication, this work demonstrates a scalable, binder-free, and mechanically resilient cathode platform for next-generation flexible Li–S battery.

Fibrous Porous Composite Interlayer Derived from Soft Dendritic Colloids for Lithium-Sulfur Batteries

ECS Meeting Abstracts · 2024-11-22

Lithium-sulfur (Li-S) batteries have emerged as a highly promising energy storage technology, owing to their high theoretical energy density and being based on abundant resources. However, they are challenged by the undesirable diffusion of soluble lithium polysulfides (LiPSs) towards the lithium metal anode in electrolytes during discharge/charge cycles, which is commonly known as the shuttle behavior of LiPSs. This phenomenon ultimately leads to the degradation of the long-term Li-S batteries stability and severely limits their practical applications. To overcome this challenge, we propose the development of an innovative composite intermediate interlayer (MWCNT/SDC-PVDF) aimed at reducing charge transfer resistance and effectively capturing dissolved polysulfides. The novel polymer composite is synthesized using a recently introduced method to produce soft dendritic colloids (SDCs). The SDCs are generated through turbulent solvent-nonsolvent induced phase separation to precisely regulate the size and morphology of precipitated PVDF across varying length scales. The integration of multiple wall carbon nanotubes (MWCNT) and SDC-PVDF within a high-shear mixer enables the formation of a homogeneous composite mixture. The resulting matrix interlayer situated between the carbon nanotubes and the SDC-PVDF fibrillar polymer network exhibits a fibrous porous structure characterized by a substantial surface area higher than 103.04 m 2 g -1 , effectively facilitating the entrapment and anchoring of LiPSs within this matrix. Furthermore, the porous framework also allows for re-utilising LiPSs in subsequent cycles to improve the irreversible of the Li-S cell. The flexible fibrous and porous MWCNT/SDC-PVDF interlayer, featuring a thin layer (∼ 55 μm ) and high conductivity, serves to mitigate cell polarization. A Li-S cell with the interlayer demonstrates a notable initial reversible capacity of 1,100 mAh g -1 at 0.2 C. The cell also achieved good capacity retention of 65% after 300 cycles at 0.2 C and 81% retention at 0.1 C after 150 cycles. Figure 1

Functional Polyvinylidene Difluoride (PVDF) Separators for Next-Generation Lithium-Sulfur Batteries

ECS Meeting Abstracts · 2024-11-22

The rising popularity of electric vehicles and the need for renewable energy storage (e.g., solar) have encouraged research into higher energy density and lower cost battery chemistries 1 . Li-S batteries possess high theoretical volumetric and gravimetric energy densities which may meet future energy demands. However, Li-S batteries have inherent barriers to sustained operation, including shuttling of soluble active material called polysulfide shuttling. This phenomenon results in rapid capacity face upon cycling due to irreversible parasitic reactions at the lithium electrode. Mitigation of polysulfide shuttling requires optimization of all cell components, including the separator, which is a key component of batteries that physically separates the anode and cathode while allowing the flow of ions between electrodes 2 . Herein we report a novel method of separator engineering that utilizes a multiphasic fabrication platform to create hierarchical membranes with tunable structures 3 . Poly(vinylidene difluoride) separators are fabricated via vacuum filtration from fibrous and nanosheet particulates. The particulates are also dispersed with SiO 2 or Al 2 O 3 to form polymer-ceramic composite separators. These separators show improved ionic conductivity (>1.5mS/cm) and thermal stability when compared to pure PVDF and Celgard separators at ambient temperature. The addition of ceramics also improves the polysulfide rejection capabilities of the membranes. Finally, full cell cycling demonstrates improved capacity retention when using the ceramic composite separators over other membrane formulations studied. Shear-driven nanofabrication is a potential means to produce ceramic-containing composite separators for future Li-S batteries. 1 Nazar, L. F., Cuisinier, M., & Pang, Q. (2014). Lithium-sulfur batteries. MRS Bulletin , 39 (5), 436–442. https://doi.org/10.1557/mrs.2014.86 2 Robinson, J. B., Xi, K., Kumar, R. V., Ferrari, A. C., Au, H., Titirici, M., Parra-Puerto, A., Kucernak, A., Fitch, S. D. S., Garcı́a-Aráez, N., Brown, Z. L., Pasta, M., Furness, L., Kibler, A. J., Walsh, D. A., Johnson, L., Holc, C., Newton, G. N., Champness, N. R., . . . Shearing, P. R. (2021). 2021 roadmap on lithium sulfur batteries. JPhys Energy , 3 (3), 031501. https://doi.org/10.1088/2515-7655/abdb9a 3 Luiso, S., Williams, A., Petrecca, M. J., Roh, S., Velev, O. D., & Fedkiw, P. S. (2021). Poly(Vinylidene difluoride) soft dendritic colloids as Li-Ion battery separators. Journal of the Electrochemical Society , 168 (2), 020517. https://doi.org/10.1149/1945-7111/abdfa7

Novel Polymeric Morphologies as Positive Electrodes in Lithium-Ion Batteries

ECS Meeting Abstracts · 2024-11-22

Growing demands for next-generation energy storage technology for utilization in consumer and grid energy storage applications have prompted a re-evaluation of lithium-ion batteries (LIBs), which are the preeminent electrochemical energy storage technology. Due to the cost and environmental impact of transition metals used in the positive electrode, researchers are investigating novel materials and processing techniques to introduce new chemistries and electrode architectures into LIBs. Herein, we propose a novel materials-processing platform to develop application-specific polymeric electrode architectures for next-generation LIBs. Organic radical polymers are of interest as an alternative positive electrode for LIBs. In particular, poly (2,2,6,6 tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) has garnered attention for its relative ease of synthesis and its fast charge-discharge kinetics. However, before implementation as an electrode, PTMA requires a significant amount of conductive additive and binder to remedy its electronically insulating polymeric backbone and its solubility in organic electrolytes, all of which decreases the gravimetric performance of PTMA. The multiphasic processing platform presented here utilizes the precipitation of PTMA in turbulent solvent-nonsolvent induced phase separation to introduce a soft dendritic colloid (SDC) morphology. Characterized by fractal branching and nanofibrillar contact splitting, the morphology of PTMA SDCs rectifies the solubility and electronic conductivity limitations associated with PTMA electrodes by introducing improved surface area and self-adhesive properties. Rate capability and cycling stability improvements are expected from PTMA SDC electrodes compared to benchmark slurry cast PTMA electrodes due to more efficient contact with conductive additives and reduced electrolyte solubility in PTMA SDCs. This hypothesis is tested and reported upon here through electrochemical analysis via cyclic voltammetry and galvanostatic charge and discharge experiments of PTMA SDC and benchmark slurry cast PTMA positive electrodes in half-cell environments against reference lithium metal electrodes.

Liquid Metal as a “Self-Healing” Agent for Phosphorus in Li-Ion Batteries

ECS Meeting Abstracts · 2024-11-22

The demand for energy storage in applications such as electric vehicles, consumer electronics and grid storage is ever increasing. Lithium-ion batteries (LIBs) are currently the state-of-art in electrochemical energy storage and are extensively used in electric vehicles and consumer electronics. To advance the state-of-art in LIBs, we propose to use gallium-based liquid metals (GLMs) as a “self-healing” agent for phosphorus in anodes. Phosphorus has a significantly larger theoretical capacity for Li + ions (2596 mAh g -1 , Li 3 P) than graphite (372 mAh g -1 , LiC 6 ). However, phosphorus suffers from pulverization due to a high-volume expansion during charging (~300%) which results in delamination of phosphorus from the anode and rapid capacity fade. 1 To address this issue, we use GLMs to fill in or “heal” defects formed from the large volume expansion of phosphorus and maintain electrical contact with any pulverized phosphorus particles. A similar strategy with GLMs has been reported in the literature with silicon which also suffers from large volume expansion. 2–6 However, to the best of our knowledge, we are the first to report the use of GLMs as a “self-healing agent” for phosphorus in LIB anodes. In our work, we fabricate a composite film electrode comprising eutectic gallium indium nanoparticles and red phosphorus nanoparticles in a carbon polymer matrix. We electrochemically characterize the electrode in coin cells with a Li half-cell configuration. Additionally, we conduct material characterizations of the electrode before and after galvanostatic charge discharge cycling. Our GLM and red phosphorus strategy may help develop effective approaches for designing anodes with high volume expansion active materials. Zhou, J. et al. Phosphorus-Based Composites as Anode Materials for Advanced Alkali Metal Ion Batteries. Adv. Funct. Mater. 30 , 2004648 (2020). Yang, J. et al. Self-Healing Silicon Anode via the Addition of GaInSn-Encapsulated Microcapsules. ACS Appl. Energy Mater. 5 , 12945–12952 (2022). Zhao, Z. et al. Liquid Metal Remedies Silicon Microparticulates Toward Highly Stable and Superior Volumetric Lithium Storage. Adv. Energy Mater. 12 , 2103565 (2022). Han, B. et al. Spontaneous repairing liquid metal/Si nanocomposite as a smart conductive-additive-free anode for lithium-ion battery. Nano Energy 50 , 359–366 (2018). Hapuarachchi, S. N. S. et al. Interfacial Engineering with Liquid Metal for Si-Based Hybrid Electrodes in Lithium-Ion Batteries. ACS Appl. Energy Mater. 3 , 5147–5152 (2020). Hapuarachchi, S. N. S. et al. Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium-Ion Batteries. Batter. Supercaps 1 , 122–128 (2018).

Next-Generation Battery Components Derived from Soft Dendritic Colloids

ECS Meeting Abstracts · 2023-12-22

Growing demands for energy storage are causing rapid development of next-generation batteries. Researchers typically use commercially available Li-ion components and processing techniques to investigate new chemistries and cell architectures. Herein, we propose an emerging materials-development platform: shear- driven precipitation of polymeric materials to develop application-specific battery components. In this process, polymer particles with high aspect ratios, called soft dendritic colloids (SDCs), are formed via turbulent solvent-nonsolvent induced phase separation. Two specific component applications are presented. The first application is nano-composite redox active polymer electrodes for Li-ion batteries. Redox polymer electrodes are currently limited by low intrinsic electronic conductivity. As a result, large amounts of conductive additives are added to the composite electrodes, lowering the gravimetric performance. The network forming capabilities of the SDC morphology provides intimate contact between active material and conductive material to enable free-standing electrodes that are produced via simple vacuum filtration. We present cyclic voltammetry and charge/discharge data using poly(2,2,6,6-tetramethyl-1-piperidinyloxy methacrylate) as the SDC material. The second application is composite separator assemblies to mitigate lithium polysulfide shuttling in Li-S batteries. Polysulfide shuttling is considered a technological hurdle plaguing Li-S battery development. Separators can be functionalized to reduce polysulfide shuttling by incorporating additives onto or within the separator matrix, which either bind or repel the soluble species to prevent crossover to the anode. We demonstrate that SDC materials are a promising platform for fabricating nanocomposite separators using a variety of nanomaterials. The nano composite separators show increased thermal stability, cycling stability, and polysulfide rejection as compared to commercial materials.

Filiform Corrosion on Polyester Powder-Coated Aluminum

ECS Meeting Abstracts · 2023-12-22

Filiform corrosion initiates and grows locally at macroscopic defects in coatings on metal substrates. While typically not detrimental to the bulk metal properties, the filiform corrosion results in threadlike filaments that propagate parallel to the surface underneath the coating. Herein, we present a study correlating the electrochemical and structural properties of polyester powder coatings onto 6022 aluminum to their associated resistance to filiform corrosion. Filiforms are propagated using a modified EN 3665 method and tracked temporally via bright field microscopy. Results including electrochemical impedance spectroscopy, open-circuit potential tracking, and potentiostatic experiments were used to evaluate coating barrier properties. Coating morphologies of pre- and post-corrosion samples are evaluated using SEM and EDX. Mechanical properties of free-standing polyester films are also characterized. The combined electrochemical and mechanical data are used to derive polyester coating design criterion to maximize resistance to filiform corrosion.

Applications of Soft Dendritic Colloids in Li-Ion Batteries with Advanced Structure-Derived Performance

ECS Meeting Abstracts · 2022-10-09

Adoption of electric vehicles and increasing demands of consumer electronics require electrochemical energy storage devices with high capacity and rate capabilities. Supply-chain and material-cost concerns as well as charge-rate limitations associated with irreversible lattice changes motivates the replacement of mixed-metal oxide cathodes in lithium-ion batteries (LIBs). Electrochemically active polymeric materials have emerged as promising candidates to replace metal oxides due to their high tunability and increased capacity. However, many of these materials suffer from poor intrinsic electronic conductivity and may be soluble into the electrolyte, causing irreversible capacity fade. Nanostructuring and composite formation are two polymer processing methods that can be leveraged to combat these drawbacks. The introduction of new nanostructured and nanocomposite cell components can decrease diffusion length scales, increase mechanical stability, and allow for higher electronic conductivity in polymer electrodes. Herein, we utilize a new class of polymeric materials called soft dendritic colloids (SDCs) as a platform for creating such nanocomposites. These fibrillar polymeric particles, formed via turbulent solvent-nonsovent induced phase separation, have hierarchical morphology, large aspect ratios and demonstrate pronounced adhesion and network-forming behavior. SDC-based materials have shown impressive results as nonwoven polyvinylidene difluoride separators in Li-ion batteries. Herein, we propose and present their use as Li-ion battery electrodes with advanced structural properties, derived from electroactive polymeric materials.