Solid-state Batteries Research Articles

Energy transition in the new era: The impact of renewable electric power on the life cycle assessment of automotive power batteries

Amid escalating global concern for environmental issues, the advancement and utilization of renewable energy take on unprecedented importance. This study focuses on the field of electric vehicle power batteries. Through constructing a life cycle assessment model, integrating various types of renewable electrical energy and various battery recovery analysis scenarios, we explored the carbon footprint and environmental impact of Nickel-Cobalt-Manganese (NCM), Lithium Iron Phosphate (LFP), All Solid State Nickel-Cobalt-Manganese (A-NCM), and All Solid State Lithium Iron Phosphate (A-LFP) batteries in the context of China. The research reveals that using renewable electrical energy could reduce carbon emissions by 50%–70 % compared to traditional energy, while also significantly enhancing other environmental performance metrics, notably with hydropower. Solid-state batteries have a more substantial environmental impact during the production phase, approximately 27 % higher than similar lithium batteries, with NCM outpacing LFP. However, in the usage phase, NCM batteries, due to their unique structure, significantly mitigate energy losses compared to LFP batteries. The study also found that hydrometallurgical recycling had superior efficiency and environmental benefits in the recycling stage. Providing a scientific foundation for sustainable policies, this study promotes the enhancement of energy structures and battery recovery in the automotive industry.

Interplay of Interfacial Adhesion and Mechanical Degradation in Anode-Free Solid-State Batteries

Abstract Anode-free solid-state batteries (AFSSBs) with an Ag-C interlayer are an innovative architecture because of their high energy density compared to conventional Li metal solid-state batteries. This work introduces simple methods to enhance the interfacial adhesion strength between the Ag-C interlayer and the solid electrolyte (SE) for better initial capacity of the cell, by controlling the cell assembling pressure to place together all components of the cell. Through contact angle experiments, our study unveils how the variation in the assembling pressure can significantly influence the contact angle between SE (at different assembling pressures) and Li metal, affecting their adhesion energy. Our electrochemical tests evidence that raising the assembling pressure from 350MPa to 530MPa outcomes an increment of more than 50% in initial capacity due to higher adhesion energies, with the corresponding energy density of 410 Wh/kg. Nonetheless, SE separator tends to crack beyond a critical assembling pressure of 530MPa that might cause a dramatic decrease of the cell performance. Our findings show that increasing the interfacial adhesion through different methods can prevent interface degradation and increase energy density of AFSSBs, affirming the vital role of interfacial adhesion between the Ag-C interlayer and SE separators, holding significant advances in anode free architectures.

Porous structural battery composite for coordinated integration of mechanical and electrical functionalities

AbstractStructural battery composites (SBCs) represent an emerging multifunctional technology in which materials functionalized with energy storage capabilities are used to build load‐bearing structural components. However, due to the liquid electrolyte contamination in structural battery electrolyte (SBE) and the large volume expansion of active battery materials, the poor interlayer interfacial in multilayer SBCs often causes difficulties in practical use. In this study, a new porous LiFePO4‐graphite SBC is designed and fabricated by independently distributing battery materials and resin matrix on carbon fiber fabric in pattern lattice form to prepare electrodes prepreg. The cured porous composite framework supports the load‐bearing function while limiting the electrochemical reaction in liquid electrolyte within lattices. The electrodes show reversible electric resistance after 3000 bending cycles with radius as small as 10 mm. The mechanical properties enhance significantly with tensile strength of 486.1 MPa and Young's modulus of 9.1 GPa compared to that with a liquid–solid biphasic mixed SBE structure. The SBC also exhibits a favorable capacity of 27.8 mAh/g at 0.1C. This straightforward integration path of mechanical and electrical functionalities is compatible with the manufacturing process of aerospace composite structures, which will provide an efficient and convenient energy supply solution for distributed electronics.Highlights A porous full‐cell structural battery composite (SBC) was designed and fabricated with prepregs. A suspension deposition and volatilization method was developed for robust battery material coating. Electrodes layer exhibited reversible electric resistance after 3000 tensile/bending cycles. The tensile strength and modulus increased significantly compared to the SBC with liquid–solid biphasic mixed structural battery electrolyte. Coordinated integration path was completely compatible with the manufacturing process of aerospace composite structures.

Praseodymium doped ceria: A new sight on coupled thermo-mechanical properties and oxygen vacancy diffusion via statistical moment approach

Applications of praseodymium doped ceria (PDC) in solid oxide fuel cells require a deep insight into the thermal expansion, stresses, and ionic conduction. Nonetheless, the investigation of thermo-mechanical properties and oxygen vacancy diffusion remains incomplete. Based on free Helmholtz energy, we formulate analytical expressions to directly connect thermal expansion coefficient, elastic moduli, oxygen vacancy–dopant binding and oxygen vacancy migration energies by employing statistical moment method (SMM). The SMM calculations capture the full anharmonicity of lattice thermal vibrations. Our analyses report the significant influences of temperature and dopant content on the thermal expansion coefficient, bulk and Young’s moduli, oxygen vacancy–dopant binding and oxygen vacancy migration energies, and ionic conductivity. The role of Pr dopant on the oxygen vacancy diffusion is fully described by combining the symmetric energy profiles related to blocking effect and asymmetric energy profiles generated from trapping effect. By switching van der Waals (vdW) forces on and off in the SMM calculations, we first show that the vdW forces cause a positive effect on the mechanical properties but reduce the thermal expansion and resist the oxygen vacancy diffusion. Our findings are discussed concerning the results from other calculations and experiments in the literature. The insights on the thermo-mechanical properties and oxygen vacancy diffusion for PDC crystal can be generalized and applied to other ceramic materials that are essential for solid state batteries.

Boosting the rate performance of all-solid-state batteries with a novel double layer solid electrolyte

When compared to traditional liquid electrolytes, solid electrolytes face significant challenges due to insufficient ionic conductivity and poor interfacial contact. To overcome these challenges, a cathode-supported double layer gradient structured solid polymer electrolyte membrane is developed. This innovative design enhances the wetting ability of the solid electrolyte on the cathode, leading to improved rate performance. Furthermore, the double layer solid electrolyte enhances mechanical strength, ensuring excellent cycling performance. As a result, the LiFePO4/Li solid state battery demonstrates superior battery performances, for instance, it can achieve a discharge capacity of 121 mAh g−1 at a current rate of 5C, with a capacity retention of 99 % after 380 cycles. This work offers a promising strategy for further enhancing the performance of all solid-state batteries.

Deep learning-driven evaluation and prediction of ion-doped NASICON materials for enhanced solid-state battery performance

NASICON (Na1+x\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{1+x}$$\\end{document}Zr2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document}Six\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_x$$\\end{document}P3-x\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{3-x}$$\\end{document}O12\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{12}$$\\end{document}) is a well-established solid-state electrolyte, renowned for its high ionic conductivity and excellent chemical stability, rendering it a promising candidate for solid-state batteries. However, the intricate influence of ion doping on their performance has been a central focus of research, with existing studies often lacking comprehensive evaluation methods. This study introduces a deep-learning-based approach to efficiently evaluate ion-doped NASICON materials. We developed a convolutional neural network (CNN) model capable of predicting the performance of various ion-doped NASICON compounds by leveraging extensive datasets from prior experimental investigation. The model demonstrated high accuracy and efficiency in predicting ionic conductivity and electrochemical properties. Key findings include the successful synthesis and validation of three NASICON materials predicted by the model, with experimental results closely matching the model’s predictions. This research not only enhances the understanding of ion-doping effects in NASICON materials but also establishes a robust framework for material design and practical applications. It bridges the gap between theoretical predictions and experimental validations.Graphical

Machine-learning-assisted deciphering of microstructural effects on ionic transport in composite materials: A case study of Li7La3Zr2O12-LiCoO2

The effective diffusivity of ionic species in multiphase materials is critical for the design and function of composite materials for electrochemical energy storage. In practice, effective diffusivity depends sensitively not only on the intrinsic diffusivities of constituting materials but also on their topological arrangement; nevertheless, these coupled contributions are oversimplified in most analytical models. Here, we combine atomistically informed mesoscale modeling and machine learning (ML) analysis to unravel how such features affect effective diffusivity in two-phase composites. Using the Li7La3Zr2O12-LiCoO2 composite solid-state battery cathode as a model system, we compute effective diffusivity for 600 distinct dense polycrystalline microstructures with different topological configurations of grains, grain boundaries, and heterointerfaces. We verify that in addition to atomic-scale variabilities, microstructural feature diversity can significantly impact effective transport properties. Across the ensemble of test microstructures, this often results in bimodal distributions of effective diffusivity that encompass two qualitatively distinct operating mechanisms, which we identify via flux analysis. An ML approach reveals that the most critical determining factors for effective diffusivity are the connectivity of bulk phases and their heterointerfaces. The role of ionic mobility at the heterointerfaces is also discussed. These insights highlight the combined importance of microstructure and interface engineering in tuning the transport properties of ionic species in composite materials. Our framework can also be extended for understanding generic microstructure-property relationships in other complex multiphase materials.

Advancing High-Energy Solid-State Batteries with High-Entropy NASICON-type Solid Electrolytes

Advancing High-Energy Solid-State Batteries with High-Entropy NASICON-type Solid Electrolytes

Space charge effects in mixed ionic-electronic conducting electrodes for solid-state batteries.

Mixed ionic-electronic conductors are widely used as electroactive materials in energy applications. The contact of a mixed conductor with another phase plays a crucial role in charge storage and transport in energy devices. However, the interfacial chemistry at the heterojunctions comprising mixed conductors and its interplay with the bulk chemistry remains imperative yet inadequately understood. This study addresses the fundamentals of space charge effects by exploring the equilibrium situations for contacts consisting of mixed conductors. From the perspective of defect chemistry, and by unifying the bulk and interfacial conditions with the electrochemical potential, our treatment allows for predicting the built-in potential at heterojunctions, profiling the space charge distributions, and evaluating the resulting interfacial charge storage and transport. The treatment can be related to experimental characterization, including coulometric titration, conductivity, and capacitance measurements at electrochemical interfaces in all-solid-state batteries. Besides, our treatment also highlights the significance of size and doping effects in nanocrystalline electrodes. This work provides a comprehensive framework for understanding and engineering the heterojunctions in electrochemical devices.

Predicting Reactivity and Passivation of Solid-State Battery Interfaces.

In this work, we build a computationally inexpensive, data-driven model that utilizes atomistic structure information to predict the reactivity of interfaces between any candidate solid-state electrolyte material and a Li metal anode. This model is trained on data from ab initio molecular dynamics (AIMD) simulations of the time evolution of the solid electrolyte-Li metal interfaces for 67 different materials. Predicting the reactivity of solid-state interfaces with ab initio techniques remains an elusive challenge in materials discovery and informatics, and previous work on predicting interfacial compatibility of solid-state Li-ion electrolytes and Li metal anodes has focused mainly on thermodynamic convex hull calculations. Our framework involves training machine learning models on AIMD data, thereby capturing information on both kinetics and thermodynamics, and then leveraging these models to predict the reactivity of thousands of new candidates in the span of seconds, avoiding the need for additional weeks-long AIMD simulations. We identify over 300 new chemically stable and over 780 passivating solid electrolytes that are predicted to be thermodynamically unfavored. Our results indicate many potential solid-state electrolyte candidates have been incorrectly labeled unstable via purely thermodynamic approaches using density functional theory (DFT) energetics, and that the pool of promising, Li-stable solid-state electrolyte materials may be much larger than previously thought from screening efforts. To showcase the value of our approach, we highlight two borate materials that were identified by our model and confirmed by further AIMD calculations to likely be highly conductive and chemically stable with Li: LiB13C2 and LiB12PC.

Solid-state Batteries: Overcoming Challenges and Harnessing Opportunities for a Sustainable Energy Future

Herein we reviewed solid-state batteries (SSBs) as an emerging and promising alternative to conventional lithium-ion batteries, offering enhanced energy density, safety, and longevity. Solid-state batteries (SSBs) use a solid electrolyte instead of the liquid or gel electrolytes found in conventional lithium-ion batteries. SSBs can achieve energy densities of up to 500 Wh/kg, compared to 350 Wh/kg for conventional lithium-ion batteries. This paper explores the potential of SSBs to revolutionize grid stability and energy storage. The unique characteristics of SSBs, including their solid-state electrolytes (SSEs) and absence of liquid components, significantly mitigate safety concerns associated with traditional batteries. Moreover, SSBs exhibit higher faster charging rates, making them ideal for applications demanding high energy storage capacity and rapid response times. The paper further discusses the key challenges and advancements in SSB development, including material selection, manufacturing processes, and cost reduction. It also highlights the anode and cathode materials but also the interface challenges faced during the design and development of SSBs. By addressing the limitations of current energy storage solutions, SSBs offer a promising pathway toward a more resilient and sustainable energy future.

Investigation of Solid Polymer Electrolytes for NASICON-Type Solid-State Symmetric Sodium-Ion Battery.

The inevitable shift toward renewable energy and electrification necessitates earth-abundant sodium reserves for next-generation Na-based energy storage technologies. By coupling the benefits of solid electrolytes over traditional nonaqueous electrolytes due to their safety hazards, solid-state sodium-ion batteries hold huge prospects in the future. This work presents a comprehensively developed solid-state sodium-ion symmetric full cell operating at room temperature enabled through a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymer electrolyte and modified NASICON-structured positive and negative electrodes. Among the investigated polymer electrolytes, PVDF-HFP-NaTFSI was found to outperform other counterparts by achieving a higher ionic conductivity and delivered an appreciable electrochemical stability window. By further delving into the properties of PVDF-HFP-NaTFSI, it was found to possess the least crystallinity, minimal porous structure, lowest melting point, and fusion enthalpy, indicating better ion transport than other investigated polymer electrolytes. The as-assembled solid-state battery revealed a storage capacity of 74 mAh g-1 at 0.1 C with a specific energy density of 130 Wh kgcathode_active_material-1 and demonstrated an impressive capacity retention of 84% of the initial capacity after 200 cycles. The structure and morphology retention of the cycled electrode and electrolyte through postmortem analysis bolster the electrochemo-mechanical stability of the developed solid cell. The findings reported here on polymer electrolytes persuade expedient solutions for developing ambient temperature solid-state sodium-ion batteries with promising electrochemical performance for commercialization in the near future.

Role of grain-level chemo-mechanics in composite cathode degradation of solid-state lithium batteries

Solid-state Li-ion batteries, based on Ni-rich oxide cathodes and Li-metal anodes, can theoretically reach a high specific energy of 393 Wh kg−1 and hold promise for electrochemical storage. However, Li intercalation-induced dimensional changes can lead to crystal defect formation in these cathodes, and contact mechanics problems between cathode and solid electrolyte. Understanding the interplay between cathode microstructure, operating conditions, micromechanics of battery materials, and capacity decay remains a challenge. Here, we present a microstructure-sensitive chemo-mechanical model to study the impact of grain-level chemo-mechanics on the degradation of composite cathodes. We reveal that crystalline anisotropy, state-of-charge-dependent Li diffusion rates, and lattice dimension changes drive dislocation formation in cathodes and contact loss at the cathode/electrolyte interface. These dislocations induce large lattice strain and trigger oxygen loss and structural degradation preferentially near the surface area of cathode particles. Moreover, contact loss is caused by the micromechanics resulting from the crystalline anisotropy of cathodes and the mechanical properties of solid electrolytes, not just operating conditions. These findings highlight the significance of grain-level cathode microstructures in causing cracking, formation of crystal defects, and chemo-mechanical degradation of solid-state batteries.

Unveiling crystal orientation-dependent interface property in composite cathodes for solid-state batteries by in situ microscopic probe

A critical bottleneck toward all-solid-state batteries lies in how the solid(electrode)-solid(electrolyte) interface is fabricated and maintained over repeated cycles. Conventional composite cathodes, with crystallographically distinct electrode/electrolyte interfaces of random particles, create complexities with varying (electro)chemical compatibilities. To address this, we employ an epitaxial model system where the crystal orientations of cathode and solid electrolyte are precisely controlled, and probe the interfaces in real-time during co-sintering by in situ electron microscopy. The interfacial reaction is highly dependent on crystal orientation/alignment, especially the availability of open ion channels. Interfaces bearing open ion paths of NCM are more susceptible to interdiffusion, but stabilize with the early formed passivation layer. Conversely, interfaces with closed ion pathway exhibit stability at intermediate temperatures, but deteriorate rapidly at high temperature due to oxygen evolution, increasing interfacial resistance. The elucidation of these distinct interfacial behaviors emphasizes the need for decoupling collective interfacial properties to enable rational design in solid-state batteries.

Development of Solid-State Lithium-Ion Batteries (LIBs) to Increase Ionic Conductivity through Interactions between Solid Electrolytes and Anode and Cathode Electrodes

Although in general ions are not able to migrate in the solid-state position due to rigid skeletal structure, in some solid electrolytes with a low energy barrier and high ionic conductivities, these ion transition can occur. In this work, we considered several solid electrolytes including lithium phosphorus oxy-nitride (LIPON), a lithium super-ionic conductor (SILICON), and thio-LISICON. For the fabrication and characterization of the solid electrolyte’s fabrication, we used a single-step ball milling (SSBM) procedure. Through this research on all-solid-state rechargeable lithium-ion batteries, our target is to discuss solving several problems in solid LIBs that have recently escalated due to raised concerns relating to safety hazards such as solvent leakage and the flammability of the liquid electrolytes used for commercial LIBs. Through this research, we tested the conductivity amounts of various substrates containing amorphous glass, SSBM, and glass-ceramic samples. Obviously, the SSBM glass-ceramics increased the conductivity, and we also found that the values for conductivity attained by SSBM were higher than those values for glass-ceramics. Using an SSBM technique, silicon nanoparticles were used as an anode material and it was found that the charge and discharge curves in the battery cell cycled between 0.009 and 1.45 V versus Li+/Li at a current density of 210 mA g−1 at room temperature. Since high resistance causes degradation between the cathode material (LiCoO2) and the solid electrolyte, we added GeS2 and SiS2 to the Li2S-P2S5 system to obtain higher conductivities and better stability of the electrode–electrolyte interface.

Research progress on improving ionic conductivity of NZSP solid electrolyte

Due to the limited resources of lithium batteries, and the safety of liquid electrolytes, and the working principle of sodium batteries and lithium batteries are similar, and the cost is relatively low, so the development of sodium ion solid state batteries has its feasibility and necessity. Among them, NASICON solid electrolyte with its unique three-dimensional structure, and good thermoelectric performance has been widely concerned, in order to better understand the development of such materials and the latest developments, this paper reviews the crystal structure of NZSP solid electrolyte, conductive mechanism, preparation methods of research progress. NZSP solid electrolyte with its room temperature asymmetric monoclinic phase and large grain boundary resistance, resulting in ionic conductivity is not enough to meet the application needs, on the basis of the above content, for the existence of NZSP ionic conductivity low problem, related discussions were carried out. The research progress of improving the ionic conductivity of NZSP based on preparation technology, grain control and grain boundary control is discussed. And in the end, the possible future development trend of NZSP material is summarized and prospected, which will play a certain reference and promotion role for the future research on NASICON solid electrolyte.

Unraveling impacts of polycrystalline microstructures on ionic conductivity of ceramic electrolytes by computational homogenization and machine learning

The ionic conductivity at the grain boundaries (GBs) in oxide ceramics is typically several orders of magnitude lower than that within the grain interior. This detrimental GB effect is the main bottleneck for designing high-performance ceramic electrolytes intended for use in solid-state lithium-ion batteries, fuel cells, and electrolyzer cells. The macroscopic ionic conductivity in oxide ceramics is essentially governed by the underlying polycrystalline microstructures where GBs and grain morphology go hand in hand. This provides the possibility to enhance the ion conductivity by microstructure engineering. To this end, a thorough understanding of microstructure–property correlation is highly desirable. In this work, we investigate numerous polycrystalline microstructure samples with varying grain and grain boundary features. Their macroscopic ionic conductivities are numerically evaluated by the finite element homogenization method, whereby the GB resistance is explicitly regarded. The influence of different microstructural features on the effective ionic conductivity is systematically studied. The microstructure–property relationships are revealed. Additionally, a graph neural network-based machine learning model is constructed and trained. It can accurately predict the effective ionic conductivity for a given polycrystalline microstructure. This work provides crucial quantitative guidelines for optimizing the ionic conducting performance of oxide ceramics by tailoring microstructures.

Lithium Volatilization and Phase Changes during Aluminum-Doped Cubic Li6.25La3Zr2Al0.25O12 (c-LLZO) Processing

Stabilized Li6.25La3Al0.25 Zr2O12 (cubic LLZO or c-LLZO) is a Li+-conducting ceramic with ionic conductivities approaching 1 mS-cm. Processing c LLZO so that it is suitable for use as a solid state electrolyte in all solid state batteries, however, is challenging due to the formation of secondary phases at elevated temperatures. The work described in this manuscript examines the formation of one such secondary phase La2Zr2O7 (LZO) formed during sintering c LLZO at 1000 °C. Specifically, spatially resolved Raman spectroscopy and X-ray Diffraction (XRD) measurements have identified gradients in Li distributions in the Li ion (Li+)-conducting ceramic Li6.25La3Al0.25 Zr2O12 (cubic LLZO or c-LLZO) created by thermal processing. Sintering c-LLZO under conditions relevant to solid state Li+ electrolyte fabrication conditions lead to Li+ loss and the formation of new phases. Specifically, sintering for 1 h at 1000 °C leads to Li+ depletion and the formation of the pyrochlore lanthanum zirconate (La2Zr2O7 or LZO), a material known to be both electronically and ionically insulating. Circular c-LLZO samples are covered on the top and bottom surfaces, exposing only the 1.6 mm-thick sample perimeter to the furnace’s ambient air. Sintered samples show a radially symmetric LZO gradient, with more LZO at the center of the pellet and considerably less LZO at the edges. This profile implies that Li+ diffusion through the material is faster than Li+ loss through volatilization, and that Li+ migration from the center of the sample to the edges is not completely reversible. These conditions lead to a net depletion of Li+ at the sample center. Findings presented in this work suggest new strategies for LLZO processing that will minimize Li+ loss during sintering, leading to a more homogeneous material with more reproducible electrochemical behavior.

Chemo-electro-mechanical phase-field simulation of interfacial nanodefects and nanovoids in solid-state batteries

Solid electrolytes encompass various types of nanodefects, including grain boundaries and nanovoids at the Li-metal/solid electrolyte interface, where lithium dendrite penetration has been extensively observed. Despite the importance of ion transport near grain boundaries with different anisotropy and the combinatorial effects with interfacial nanovoids, a comprehensive understanding of these phenomena has remains elusive. Here, we develop a chemo-electro-mechanical phase-field model to elucidate how Li penetrates Li7La3Zr2O12 in the co-presence of grain boundaries and interfacial nanovoids. The investigation unveils a grain-boundary-anisotropy-dependent behavior for Li-ion transport correlated with the presence of interfacial nanovoids. Notably, the Σ1 grain boundary exhibits faster Li dendrite growth, particularly in the co-presence of interfacial nanovoids. The model quantitatively reveals whether interfacial electronic properties dominate Li dendrite morphology and penetration, providing a strategy for designing stable Li/solid electrolyte interfaces. These findings help prioritize approaches for optimally tailoring nanodefects and exploiting synergetic effects at the interface to prevent dendrite formation.

Effect of the Formation Rate on the Stability of Anode-Free Lithium Metal Batteries.

Anode-free Li-ion batteries (AFBs), where a Cu current collector is used to plate and strip Li instead of a classic anode, are promising technologies to increase the energy density of batteries. In addition, AFBs are safer and easier to manufacture than competing Li-metal anodes and solid-state batteries. However, the loss of Li inventory that occurs during the operation of AFBs limits their lifespan and practical application. In this study, we find that, in particular, the current density used during the formation of AFBs has a considerable impact on the cycling stability of the cell. We optimize the formation protocol based on experimental and computational observations of thresholds associated with morphological changes in the plated Li and the chemical composition of the solid-electrolyte interphase. Unlike graphite anodes, which require slow formation cycles, AFBs exhibit improved cycling behavior when formed at the highest current densities that avoid dendritic Li formation. We verify that this strategy for optimizing the formation current density is effective for three different electrolyte formulations and, therefore, provides a straightforward universal rationale to optimize the formation protocols for AFBs.