Dendritic Generation Research Articles

KxNayH(2‐x‐y)Ti2O5 for High‐Performance Lithium‐Ion Battery Anode with Li Dendrites‐Free Mechanism, Zero‐Strain Characteristic

AbstractConventional Li‐ion batteries equipped with graphite anodes suffer from poor rate performance and the risk of lithium dendrites, which constrain scale‐up applications. Among the promising candidates, spinel‐type Li4Ti5O12 is still subjected to low theoretical specific capacity, high working potential, and poor diffusion properties. Herein the KxNayH(2‐x‐y)Ti2O5 product is provided by reconstructing the chemical bonding idea, which exhibits enhanced specific capacity (323 mAh g−1), lower working potential (major capacity contribution < 1.5 V vs Li+/Li), higher diffusion coefficient (10−8.5–10−5 cm2 s−1), and long cycle stability. Further in/ex situ studies show that these excellent properties can be attributed to the combination of high capacitive contribution, unique “switching mechanism” to avoid lithium dendrite generation, and the zero‐strain properties. The findings provide new ideas and opportunities for the development of next generation titanate anode materials with desirable electrochemical properties.

NaF-Rich Multifunctional Layers toward Stable All-Solid-State Sodium Batteries.

NASICON oxide solid electrolytes are considered promising candidates for all-solid-state sodium batteries due to their extremely high ionic conductivity and favorable electrochemical stability. However, the practical application of NASICON electrolytes is greatly impeded by poor electrolyte-electrode interfacial contact and continuous sodium dendrite propagation. Herein, a NaF-rich multifunctional interface layer on the surface of a Na anode (Na@NaF-rich), containing NaF, amorphous carbon, and an unreacted C-F bond species, is developed in situ by the reaction between Na and commercial poly(tetrafluoroethylene). This NaF-rich interface layer is proven to reduce the diffusion barriers at the Na/NASICON electrolyte interface and homogenize Na deposition as well as suppress Na dendrite growth, thus achieving a high critical current density of 4 mA cm-2. The resultant Na3V2(PO4)3@C/Na@NaF-rich all-solid-state cell showed a high initial specific capacity of 117.6 mAh g-1 at 0.1 C with a Coulombic efficiency of 94.8%. Even at 0.5 and 1 C, it still exhibited high capacity retentions of 83.3% and 80.4%, respectively, after 750 cycles.

Electrode-supported high-tortuosity zeolite separator enabling fast-charging and dendrite-free lithium-ion/metal batteries

Lithium-metal batteries (LMBs) are poised to be the next-generation high-energy density storage media of choice for various applications; however, they are currently plagued by failure due to dendrite propagation at high charge/discharge rates. One of the most sought-after technologies for dendrite propagation prevention in LMBs is solid state batteries, but they face commercialization challenges due to low room temperature ionic conductivity and high manufacturing cost. Here, we report the use of plate-shaped zeolite particles with intraparticle crystalline micropores to form an electrode-coated separator by a scalable blade-coating methodology. These separators with minimal polymer content are non-flammable and highly wettable to organic-based liquid electrolytes. They have high pore tortuosity and shear modulus resulting from the unique physical properties and morphology of the plate-shaped zeolite particles. LMB cells made of a LiNi0.5Co0.2Mn0.3O2 (NMC) cathode, coated with the plate-shaped zeolite separator, LiPF6-carbonate electrolyte, and lithium metal anode, show good charge-discharge characteristics and effectiveness in preventing dendrites from propagating through the separator even at high (3 C-rate) rates. When compared to LMB cells with a tortuously porous separator of similar pore size and porosity made of dense plate-shaped γ-alumina particles without intraparticle pores, cells with the zeolite separator show better charge/discharge characteristics, lower solid electrolyte interface (SEI) and charge-transfer resistances, and more effective dendrite propagation prevention. Results suggest that the intraparticle pores of the zeolite separator particles homogenize the Li-ion flux at the separator-anode interface in a much better manner than γ-alumina particles. There is promising commercial potential for the electrode-coated zeolite separator with highly tortuous pores for lithium batteries with a lithium-metal anode.

(Invited) Three-Dimensional Modeling of Dendrite Formation during Rapid Charging

Dendrites commonly form during rapid charging of lithium-ion batteries when plating is favored over intercalation. If not mitigated, the potential exists for dendrites to growth through the separator and short the anode and cathode. One metric for diagnosing plating conditions in a computational model is the minimum local potential at the anode, where plating is seen to be thermodynamically favorable below 0.0 V with respect to Li metal.[1, 2] Three-dimensional (3D) models can offer insight to predict the possibility of local lithium plating and can be used as a tool to detect possible global lithium plating onset, so it follows that 3D microstructure models can be used to predict dendrite formation and propagation as well. The volume of fluid (VoF) method, which is commonly used to model the flow of immiscible fluids, can be used to divide the electrolyte region into a liquid phase and a dendrite phase.[3] This strategy is implemented in a 3D microstructure model of a lithium-ion battery to observe the growth of dendrites at the anode during rapid charging. Under onset conditions at the solid/electrolyte interface (SEI), the solid metal phase is deposited at the SEI. Upon growth, the overall electrolyte resistance at the tip of the metal phase is reduced, leading to dendrite growth. The 3D model provides valuable insight into various conditions that may cause plating, if dendrites are formed due to plating, and whether the dendrites formed may proceed to a shorting evenReference T. R. Garrick, J. Gao, X. Yang and B. J. Koch, J Electrochem Soc, 168, 010530 (2021).U. Janakiraman, T. R. Garrick and M. E. Fortier, J Electrochem Soc, 167, 160552 (2020).T. Jang, L. Mishra, S. A. Roberts, B. Planden, A. Subramaniam, M. Uppaluri, D. Linder, M. P. Gururajan, J.-G. Zhang and V. R. Subramanian, J Electrochem Soc, 169, 080516 (2022).

(Invited) Understanding the Role of Mixed Ionic-Electronic Conductor Interlayer in All-Solid-State Lithium-Metal Batteries

All-solid-state lithium metal batteries are projected to offer one of the highest specific energy among rechargeable batteries. However, a major challenge in these batteries is the poor lithium-solid electrolyte contact and void formation at the interface during Li plating and stripping. To address this challenge, an interlayer strategy has been introduced between the solid electrolyte and the lithium metal to promote better interfacial contact, improve stripping/plating homogeneity, and therefore suppress lithium dendrite formation and propagation. In particular, a MIEC-type interlayer, composed of carbon-based materials that conduct both Li+ ions and electrons and have a certain lithium storage capacity, has been employed between the anode current collector and the electrolyte, allowing for over 1000 cycles at a high current density. While the use of a MIEC-type interlayer has only recently gained attention, many aspects of its working mechanism remain unclear. For example, where does lithium deposit in the interlayer, and what determines the deposition location? How does lithium transport in the interlayer? Is Li0 or Li+ transporting? In this talk, we will present our findings to better understand the interlayer physiochemical properties and lithium deposition behavior in order to achieve rational design of a MIEC-type interlayer.Acknowledgement: This work was supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Vehicle Technologies Program under Contact DE-EE0008864.

(Invited) Achieving High Areal Capacity and Extreme Critical Current Densities through Tailored Garnet Solid Electrolyte Structures

Garnet structured electrolytes are an exceptional candidate to substitute for organic liquid electrolytes owing to its high ionic conductivity and safety.[1] One of the main issues preventing the commercialization of this electrolyte is limited lithium plating capacity and lithium dendrite shorting.[2] To address this, we invented new single-phase mixed ion electron conducting (MIEC) garnet with comparable lithium-ion and electron conductivity at room temperature. We demonstrate that in a trilayer architecture, with a porous MIEC framework supporting a thin dense garnet solid electrolyte, the critical current density can be as high as 100 mA/cm2, with no dendrite-induced shorting at room temperature and without any stack pressure. The single-phase MIEC conductor spreads the potential uniformly across the material surface preventing dendrite propagation through the dense garnet solid electrolyte layer. Additionally, high lithium stripping capacity and impressive cycling stability were observed at commercial level current densities of well over 10 mA/cm2. The role of the porous MIEC garnet structure is elucidated using various electrochemical and electron microscopy techniques. Wang, C. et al. Garnet-Type Solid-State Electrolytes: Materials, Interfaces, and Batteries. Chem. Rev. 120, 4257–4300 (2020).Albertus, P., Babinec, S., Litzelman, S. & Newman, A. Status and challenges in enabling the lithium metal electrode for high-energy and low-cost rechargeable batteries. Nat. Energy 2017 31 3, 16–21 (2017).

Electrochemical Characterization of Thiophosphate- Ionic Liquid Hybrid Lithium Electrolytes Against Li Metal

(Almost) solid-state batteries that utilize thiophosphate solid electrolytes (SE) are an exciting technology emerging as a potential alternative to lithium-ion batteries. When used alongside a lithium metal anode they can offer the high energy densities [1] required to meet the increasing demand for energy storage. However, they suffer from numerous issues which predominately occur at the cathode- or anode-SE interface. Issues include dendrite propagation through gaps, pores and grain boundaries of the solid electrolyte which can eventually puncture electrolyte crystallites and lead to cell failure. [2] Thiophosphate electrolytes are also unstable both chemically and electrochemically. As a result of the SEs having a low electrochemical stability window reduction or oxidation can occur at the anode or cathode interface, forming a resistive solid electrolyte interphase (SEI). [3] Finally, the ionic contact between Li metal anode and electrolyte is poor and thus high interfacial impedances can arise. These impedances can be dynamic which increase during stripping of the lithium and decrease during plating. [4] To solve some of the interfacial issues there is the option to add a small of amount of liquid electrolyte at the lithium metal-electrolyte interface. The liquid electrolyte can fill in the gaps and pores at the interface thus improving the ionic contact whilst allowing a more stable interface. Whilst the ionic contact can be improved the inherent instability of thiophosphate electrolytes against the liquid electrolyte means that a new interphase known as the solid-liquid electrolyte interphase (SLEI) can form. The presence of this interphase can therefore lower the energy density and round-trip efficiencies of cells which utilize hybrid electrolytes meaning that minimizing the SLEI resistance and maximizing total ionic conductivities is important in hybrid cells. [5]In this work a hybrid of the thiophosphate argyrodite Li6PS5Cl and the ionic liquid x-LiTFSI-1-butyl 1-methylpiperidinium TFSI (BMPipTFSI) with LiTFSI concentrations of 0.25 M and 0.5 M was studied. The choice of SE and liquid electrolyte boils down to the high ionic conductivity of the SE and the electrochemical and thermal stability of the ionic liquid. Temperature-dependent ionic conductivity measurements showed that hybrid systems exhibit lower in room temperature ionic conductivities and higher total activation energies. This hints at the presence of a SLEI forming between the LE and SE. To study how the SLEI resistances changes over time, ion blocking potential impedance spectroscopy measurements were performed. These measurements were performed at 10 °C to allow for the resistance contributions to be better resolved and showed a SLEI resistance of around 45-50 Ω cm2 for both hybrids. Over the period of 130 hours this resistance changed minimally (around 5 Ω cm2 on average) indicating good stability of the SLEI. To further test the suitability of this hybrid alongside lithium metal anodes impedance measurements in symmetrical lithium cells (Li0|LE|LPCL|LE|Li0) were undertaken. In this case galvanostatic impedance spectroscopy (GEIS) with an applied current density of ±0.4 mA cm-2 was used to probe the changes in resistance contributions in the system over the period of stripping (positive current) and plating (negative current). For cells with just SE a large change in the resistance owing to the electrochemical reaction (ECR) (Li0 ↔ Li+ + e-) occurred during stripping and plating indicating the dynamic nature of the ionic contact at the interface. For the hybrid electrolyte cells, this ECR resistance is decreased and becomes more stable however a larger interphase resistance is present. This resistance is a combination of the resistances of both the SLEI (the interphase between the LE and SE) and the SEI (the interphase between LE and Li anode) and it changes over stripping and plating showing that the S(L)EIs which are present are dynamic. Finally, post-mortem SEM/EDX of the surface of samples show a change in morphology and the presence of decomposition products from both the liquid and solid electrolytes. These studies show that the LPCL-BMPipTFSI hybrid is stable and improve ionic contact at the lithium metal anode interface. Further testing in half Li-S cells will determine the suitability of the use of the ionic liquid at the cathode side of the cell.

Understanding the Interplay between Electrochemistry and Mechanics at Dendrite Tips in Sulfide and Oxide Electrolytes

Dendrite-induced short circuits threaten the deployment of solid-state batteries with metal anodes. Whether dendrites grow by internal chemical reduction of lithium or because of mechanical stresses has been a topic of debate. For both oxide and electrolyte electrolytes, we address this question by conducting operando microscopy to observe mechanical and electrochemical phenomena underlying dendrite growth. Here, we build upon the method from Athanasiou-Fincher et al. to observe stress-optic couplings around dendrite tips in thin oxide electrolytes[1]. Specifically, operando measurements of dendrite-induced stress fields are measured as a function of applied potential, and then the images are quantitatively analyzed to measure the mechanical driving forces underlying failure (i.e., the energy release rate). These operando measurements demonstrate a complex interplay between electrochemistry and mechanics. We develop a mechanistic framework to describe the observed behavior, discussed in juxtaposition with stress-corrosion cracking and linear elastic fracture mechanics. The resulting implications for electrolyte testing and design are discussed. Lastly, we assess whether mechanical stresses in electrolytes can be used to “steer” the dendrite growth directory. By dynamically applying mechanical loads to growing dendrites in LLZTO, we show that dendrite growth trajectory can be deflected to avoid short-circuit failures in oxide electrolytes[2]. Together, these results demonstrate a complex relationship between electrochemical and mechanical driving forces. Despite the observed complexity, processing-induced residual stresses can deflect dendrites and avert short circuits.[1] CE Athanasiou=, CD Fincher=, C Gilgenbach, WC Carter, H Gao, YM Chiang, BW Sheldon. Manuscript in preparation. “On the Use of Photoelasticity for Operando Dendrite-Induced Stress Quantification in Ceramic Electrolytes,” 2022 Materials Research Society Fall Conference; manuscript in preparation.[2] CD Fincher, CE Athansiou, C Gilgenbach, MJ Wang, BW Sheldon, WC Carter, YM Chiang, “Controlling dendrite propagation in solid-state batteries with engineered stress,” Joule, in press. DOIs: 10.1016/j.joule.2022.10.011

Interfacial Dynamics of Carbon Interlayers at Anode-Free Solid Electrolyte/Lithium Interfaces

Solid electrolytes (SEs) that incorporate lithium (Li) metal anodes provide a promising pathway to improve battery energy density and safety. However, Li metal anodes still suffer from multiple challenges, including 1) uniform Li deposition and dissolution, 2) continual formation of a solid-electrolyte interphase (SEI), and 3) limited rate capability. To control the interfaces, predefined interlayers such as gold, ZnO, carbon, and other coatings have been used tune the Li metal and SE interface. However, there is a need for improved fundamental understanding of the mechanistic role of these interlayers on performance and stability. In this work, we explore the application of an amorphous carbon interlayer in an argyrodite SE system, which is used for in situ Li metal formation in an “anode-free” configuration.The incorporation of a carbon interlayer has been previously shown to act as a physical barrier between the SE and in situ formed Li metal, improve the uniform contact and current distribution across the SE/anode interface, and potentially suppress dendrite propagation [1]. However, the mechanism of this improved performance is not fully understood. Therefore, to study the influence of the carbon interlayer on interfacial performance, a detailed electrochemical analysis was performed.First, the transition in reaction pathway from carbon lithiation to Li nucleation and growth was observed to change as a function of charging rates. To probe the lithiation effects of the carbon interlayer on subsequent Li deposition, incremental electrochemical impedance spectroscopy (EIS) and current-interrupt analysis was performed to study the dynamic changes of the carbon interlayer during the charging process prior to Li nucleation. To confirm the mode of metallic Li nucleation and growth, operando video microscopy and post-mortem focused ion-beam/scanning electron microscopy (FIB-SEM) was utilized. The preferential location of Li deposition and growth at the current collector and carbon interface confirms the transport of Li-ion through the lithiated carbon interlayer. Moreover, the Li metal deposition behavior was observed to depend on the electrochemical properties of the carbon interlayer during the lithiation process. These fundamental electrochemical studies will further our understanding of the design requirements for interlayers that can enable Li metal anodes in solid-state battery systems.[1] Y.G. Lee, S. Fujiki, C. Jung, N. Suzuki, N. Yashiro, R. Omoda, D. S. Ko, T. Shiratsuchi, T. Sugimoto, S. Ryu, J. H. Ku, T. Watanabe, Y. Park, Y. Aihara, D. Im, I. T. Han, Nat. Ener. 5, 299-308 (2020)

Extrusion 3D Printing of Patterned Cu Current Collectors for Advanced Lithium Metal Anodes

AbstractLithium (Li) metal is the most attractive anode material for the next generation Li batteries. However, crucial open challenges still limit its applicability at large scale, such as the low coulombic efficiency, unstable electrodeposition, and dendrite propagation with severe safety concerns. One strategy to address these drawbacks is the rational design of innovative current collectors for the Li anode. Here, we report on a simple, low‐cost, and easily scalable process based on Additive Manufacturing technology via extrusion 3D printing to produce Cu current collectors with different and tuneable patterned structures. The current collectors are characterized by means of X‐ray diffractometry, electron microscopy, profilometry and galvanostatic cycling. We show that the three‐dimensional network can significantly stabilize the electrodeposition of Li, thanks to an enhanced electroactive surface area that enables a better Li accommodation without uncontrollable dendrite growth. Contrary to the planar current collector, the Li anode supported by the 3D current collectors exhibits stable and low voltage hysteresis at different current densities and can run for at least 330 hours without short‐circuiting. Moreover, the evaluation of Li@3DCu anode in a LiFePO4‐based full cell by galvanostatic cycling reveals excellent rate performances, achieving specific capacity exceeding 100 mAh g−1 at 1 C and coulombic efficiency higher than 99 %. These results show that the material extrusion 3D printing approach is a versatile strategy to develop new and safer anodes with a long lifespan and reduced amount of Li metal.

Self assembled electron blocking and lithiophilic interface towards dendrite-free solid-state lithium battery

The poor interfacial contact is one of the biggest challenges that solid-state lithium batteries suffer from. Reducing the solid-state electrolyte surface energy by transforming the interface from lithiophobic to lithiophilic is effective to promote the interfacial contact, but electronic conductive interphases usually increase the risk of electron attack, thus leading to uncontrollable Li dendrite growth. Herein, we propose a self-assembled thermodynamic stable LiI interphase to simultaneously improve the interfacial contact between the garnet electrolyte Li7La3Zr2O12 (LLZO) and Li anode, and prohibit the electron attack. The direct contact between LLZO and Li and the high temperature Li melting process was ascribed to Zr4+ reduction, which facilitated Li dendrite formation and propagation. With the modification of the high lithiophilic I2 thin film, the area specific interfacial resistance of LLZO/Li was reduced from 1525 Ω/cm2 to 57 Ω/cm2. More importantly, LLZO was protected from being reduced due to the outstanding electronic insulativity of the LiI interphase, which leaded to a high critical current density of 1.2/7.0 mA/cm2 in the time/capacity-constant modes, respectively.

3D Printing-Enabled Design and Manufacturing Strategies for Batteries: A Review.

Lithium-ion batteries (LIBs) have significantly impacted the daily lives, finding broad applications in various industries such as consumer electronics, electric vehicles, medical devices, aerospace, and power tools. However, they still face issues (i.e., safety due to dendrite propagation, manufacturing cost, random porosities, and basic & planar geometries) that hinder their widespread applications as the demand for LIBs rapidly increases in all sectors due to their high energy and power density values compared to other batteries. Additive manufacturing (AM) is a promising technique for creating precise and programmable structures in energy storage devices. This review first summarizes light, filament, powder, and jetting-based 3D printing methods with the status on current trends and limitations for each AM technology. The paper also delves into 3D printing-enabled electrodes (both anodes and cathodes) and solid-state electrolytes for LIBs, emphasizing the current state-of-the-art materials, manufacturing methods, and properties/performance. Additionally, the current challenges in the AM for electrochemical energy storage (EES) applications, including limited materials, low processing precision, codesign/comanufacturing concepts for complete battery printing, machine learning (ML)/artificial intelligence (AI) for processing optimization and data analysis, environmental risks, and the potential of 4D printing in advanced battery applications, are also presented.

Design Principles for Grain Boundaries in Solid‐State Lithium‐Ion Conductors

AbstractLithium dendrite formation and insufficient ionic conductivity remain primary concerns for the utilization of solid‐state batteries. Given that the interpretation of experimental results for polycrystalline solid electrolytes can be difficult, computational techniques are invaluable for providing insight at the atomic scale. Here, first‐principles calculations are carried out on representative grain boundaries in four important solid electrolytes, namely, an anti‐perovskite oxide, Li3OCl, and its hydrated counterpart, Li2OHCl, a thiophosphate, Li3PS4, and a halide, Li3InCl6, to develop the first generally applicable design principles for grain boundaries in solid electrolytes for solid‐state batteries. The significantly different impacts that grain boundaries have on electronic structure and transport, ion conductivity and correlated ion dynamics are demonstrated. The results show that even when grain boundaries do not significantly impact ionic conductivity, they can still strongly perturb the electronic structure and contribute to potential lithium dendrite propagation. It is also illustrated, for the first time, how correlated motion, including the so‐called paddle‐wheel mechanism, can vary substantially at grain boundaries. These findings reveal the dramatically different behavior of solid electrolytes at the microscale compared to the bulk and its potential consequences and benefits for the design of solid‐state batteries. These design principles are expected to aid the synthesis and engineering of solid electrolytes at the microscale for preventing dendrite propagation and accelerating ion transport.

Polyolefin‐Based Separator with Interfacial Chemistry Regulation for Robust Potassium Metal Batteries

AbstractPotassium metal batteries (KMBs) are ideal choices for high energy density storage system owing to the low electrochemical potential and low cost of K. However, the practical KMB applications suffer from intrinsically active K anode, which would bring serious safety concerns due to easier generation of dendrites. Herein, to explore a facile approach to tackle this issue, we propose to regulate K plating/stripping via interfacial chemistry engineering of commercial polyolefin‐based separator using multiple functional units integrated in tailored metal organic framework. As a case study, the functional units of MIL‐101(Cr) offer high elastic modulus, facilitate the dissociation of potassium salt, improve the K+ transfer number and homogenize the K+ flux at the electrode/electrolyte interface. Benefiting from these favorable features, uniform and stable K plating/stripping is realized with the regulated separator. Full battery assembled with the regulated separator showed ∼19.9 % higher discharge capacity than that with glass fiber separator at 20 mA g−1 and much better cycling stability at high rates. The generality of our approach is validated with KMBs using different cathodes and electrolytes. We envision that the strategy to suppress dendrite formation by commercial separator surface engineering using tailor‐designed functional units can be extended to other metal/metal ion batteries.

Integration Plasma Strategy Controlled Interfacial Chemistry Regulation Enabling Planar Lithium Growth in Solid‐State Lithium Metal Batteries

AbstractSolid‐state lithium metal batteries (SSLMBs) are identified as a highly promising candidate for next‐generation energy storage devices, yet they still face uncontrollable dendritic lithium (Li) growth originating from interfacial incompatibility. To address this issue, an “integration plasma (IP)” strategy for interlayer construction is proposed that integrates metal reduction and vapor deposition functions, featuring the ability to give a manipulable and quantifiable chemical regulation for controlling the surface concentration (Csurface) and the atomic ratio of the introduced metal element and electronegative element (ARE/M) on solid‐state electrolyte (SSE). This IP‐formed interlayer can in situ react with Li anode to synchronously produce metal‐Li alloy, Li salt and amorphous carbon, thus offering an “integrated function” to promote a spherical and hexagonal Li growth, preventing the dendrite propagation from SSE. When Csurface of metal elements and corresponding ARE/M is regulated as ≈1.13 nmol cm‐2 and ≈2.6, the IP‐modified SSE prolongs the lifespan of SSLMBs with LiNi0.8Co0.1Mn0.1O2 cathode to over 1000 cycles with a low‐capacity attenuation of 0.03% per cycle, highlighting the multiply functions of IP to accelerate the practical application of SSLMBs.

Dendritic propagation on circular electrodes: The impact of curvature on the packing density.

The dendritic growth in rechargeable batteries is one of the hurdles for the utilization of high energy-density elements, such as alkaline metals, as the electrode. Herein we explore the preventive role of the curved electrode surface in the cylindrical electrode design versus the flat geometry on the stochastic evolution of the dendritic crystals. In this regard we establish a coarse-grained Monte Carlo paradigm in the polar coordinates (r,θ), which runs in a larger scale of time and space (∼μs,∼nm ) than those of interionic collisions (∼fs, Å). Subsequently we track the density and the maximum reach of the microstructures in real time, and we elaborate on the underlying mechanisms for their correlation of the relative dendrite measure with the electrode curvature. Such quantification of the positive impact of the curvature on suppressing dendrites could be utilized as an effective longevity design parameter, particularly for the cases prone to dendritic propagation.

Enhanced in vitro type 1 conventional dendritic cell generation via the recruitment of hematopoietic stem cells and early progenitors by Kit ligand.

In vitro culture of bone marrow (BM) with Fms-like tyrosine kinase 3 ligand (Flt3L) is widely used to study development and function of type 1 conventional dendritic cells (cDC1). Hematopoietic stem cells (HSCs) and many progenitor populations that possess cDC1 potential in vivo do not express Flt3 and thus may not contribute to Flt3L-mediated cDC1 production in vitro. Here, we present a KitL/Flt3L protocol that recruits such HSCs and progenitors into the production of cDC1. Kit ligand (KitL) is used to expand HSCs and early progenitors lacking Flt3 expression into later stage where Flt3 is expressed. Following this initial KitL phase, a second Flt3L phase is used to support the final production of DCs. With this two-stage culture, we achieved approximately tenfold increased production of both cDC1 and cDC2 compared to Flt3L culture. cDC1 derived from this culture are similar to in vivo cDC1 in their dependence on IRF8, ability to produce IL-12, and induction of tumor regression in cDC1-deficient tumor-bearing mice. This KitL/Flt3L system for cDC1 production will be useful in further analysis of cDC1 that rely on in vitro generation from BM.

Insight into the role of crystallinity in oxide electrolytes enabling high-performance all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) would be a promising candidate for the next-generation batteries due to the utilization of energy-dense electrodes and the non-flammable oxide solid-state electrolytes (SSEs), but still face great challenges such as low ionic conductivity of SSEs, poor interfacial contact and lithium (Li) dendrite propagation. Herein, we regulated the crystallinity degrees of the large-scale-fabricated Li1.5Al0.5Ge1.5(PO4)3 (LAGP) SSEs and explored the critical role of crystallinity optimization in reinforcing the basic properties of LAGP, developing a fundamental explanation for the inherent relation between the crystallinity and the performance of ASSLSBs. Benefiting from the optimized crystallinity (∼99.9 %), the large-scale-fabricated LAGP not only realizes the low surface roughness and high ionic conductivity (2.11 × 10−4 S cm−1) to improve interfacial contact and reduce resistance in ASSLSBs, but also possesses the dense internal structure with low porosity (1.49 %) to physically resist dendritic propagation and penetration. Consequently, the ASSLSB with the optimized LAGP delivers a high reversible capacity of 647.9 mAh/g even after 150 cycles at 0.1 C. This work confirms the significance of crystallinity in understanding the working mechanisms of oxide SSEs and developing future high-performance ASSLSBs.

SnF2‐Induced Highly Current‐Tolerant Solid Electrolytes for Solid‐State Sodium Batteries

AbstractSolid‐state sodium batteries have garnered considerable interest. However, their electrochemical performance is hampered by severe interfacial resistance between sodium metal and inorganic solid electrolytes, as well as Na dendrite growth within the electrolytes. To address these issues, a uniform and compact SnF2 film is first introduced onto the surface of the inorganic solid electrolyte Na3.2Zr1.9Ca0.1Si2PO12 (NCZSP) to improve contact through an effective and straightforward process. Through experiments and computations, the in situ conversion reaction between SnF2 and molten Na is adequately confirmed, resulting in a composite conductive layer containing NaxSn alloys and NaF at the interface. As a result, the interfacial resistance of Na/NCZSP is significantly decreased from 813 to 5 Ω cm2, and the critical current density is dramatically increased to 1.8 mA cm−2, as opposed to 0.2 mA cm−2 with bare NCZSP. The symmetric cell is able to cycle stably at 0.2 mA cm−2 for 1300 h at 30 °C and exhibits excellent current tolerance of 0.3 and 0.5 mA cm−2. Moreover, the Na3V2(PO4)3/SnF2‐NCZSP/Na full cell displays excellent rate performance and cycling stability. The SnF2‐induced interlayer proves significant in improving interfacial contact and restraining sodium dendrite propagation, thus promoting the development of solid‐state sodium batteries.

The Entanglement of Li Capping and Deposition: An Operando Optical Microscopy Study.

Dendrite growth and low Coulombic efficiency impede the practical application of Li-metal batteries. As such, monitoring Li deposition and stripping in real-time is crucial to understanding the fundamental lithium growth kinetics. This work presents an operando optical microscopic technique that enables precise current density control and quantification of Li layer properties (i.e., thickness and porosity) to study Li growth in various electrolytes. We discover the robustness and porosity of the remaining capping layer after the Li stripping process as the critical features governing the subsequent dendrite propagation behavior, resulting in distinct capping and stacking phenomena that affect Li growth upon cycling. While dendrite propagation quickly occurs through the fracture of the fragile Li capping layer, uniform Li plating/stripping can be facilitated by the compact and robust capping layer even at high current densities. This technique can be extended to evaluate dendrite suppression treatments in various metal batteries, providing in-depth information on metal growth mechanisms.