Deposition of Sodium Metal at the Copper‐NaSICON Interface for Reservoir‐Free Solid‐State Sodium Batteries

“Anode-free” solid-state battery concepts are explored extensively as they promise a higher energy density with less material consumption and simple anode processing. Here, the homogeneous and uniform electrochemical deposition of alkali metal at the interface between current collector and solid electrolyte plays the central role to form a metal anode within the first cycle. While the cathodic deposition of lithium has been studied intensively, knowledge on sodium deposition is scarce. In this work, dense and uniform sodium layers of several microns thickness are deposited at the Cu|Na$_{3.4}$Zr$_2$Si$_{2.4}$P$_{0.6}$O$_{12}$ interface with high reproducibility. At current densities of ≈1 mA∙cm$^{−2}$, relatively uniform coverage is achieved underneath the current collector, as shown by electrochemical impedance spectroscopy and 3D confocal microscopy. In contrast, only slight variations of the coverage are observed at different stack pressures. Early stages of the sodium metal growth are analyzed by in situ transmission electron microscopy revealing oriented growth of sodium. The results demonstrate that reservoir-free (“anode-free”) sodium-based batteries are feasible and may stimulate further research efforts in sodium-based solid-state batteries

Kinetics and Pore Formation of the Sodium Metal Anode on NASICON‐Type Na3.4_{3.4} Zr2_2Si2.4_{2.4}P0.6_{0.6}O12_{12} for Sodium Solid‐State Batteries

In recent years, many efforts have been made to introduce reversible alkali metal anodes using solid electrolytes in order to increase the energy density of next-generation batteries. In this respect, Na$_{3.4}$Zr$_2$Si$_{2.4}$P$_{0.6}$O$_{12}$ is a promising solid electrolyte for solid-state sodium batteries, due to its high ionic conductivity and apparent stability versus sodium metal. The formation of a kinetically stable interphase in contact with sodium metal is revealed by time-resolved impedance analysis, in situ X-ray photoelectron spectroscopy, and transmission electron microscopy. Based on pressure- and temperature-dependent impedance analyses, it is concluded that the Na|Na$_{3.4}$Zr$_2$Si$_{2.4}$P$_{0.6}$O$_{12}$ interface kinetics is dominated by current constriction rather than by charge transfer. Cross-sections of the interface after anodic dissolution at various mechanical loads visualize the formed pore structure due to the accumulation of vacancies near the interface. The temporal evolution of the pore morphology after anodic dissolution is monitored by time-resolved impedance analysis. Equilibration of the interface is observed even under extremely low external mechanical load, which is attributed to fast vacancy diffusion in sodium metal, while equilibration is faster and mainly caused by creep at increased external load. The presented information provides useful insights into a more profound evaluation of the sodium metal anode in solid-state batteries

The Impact of Microstructure on Filament Growth at the Sodium Metal Anode in All‐Solid‐State Sodium Batteries

In recent years, all-solid-state batteries (ASSBs) with metal anodes have witnessed significant developments due to their high energy and powerdensity as well as their excellent safety record. While intergranular dendriticlithium growth in inorganic solid electrolytes (SEs) has been extensively studied for lithium ASSBs, comparable knowledge is missing forsodium-based ASSBs. Therefore, polycrystalline Na-′′-alumina is employedas a SE model material to investigate the microstructural influence on sodiumfilament growth during deposition of sodium metal at the anode. The research focuses on the relationship between the microstructure, in particular grainboundary (GB) type and orientation, sodium filament growth, and sodium iontransport, utilizing in situ transmission electron microscopy (TEM) measurements in combination with crystal orientation analysis. The effect ofthe anisotropic sodium ion transport at/across GBs depending on theorientation of the sodium ion transport planes and the applied electric field on the current distribution and the position of sodium filament growth is explored. The in situ TEM analysis is validated by large field of viewpost-mortem secondary ion mass spectrometer (SIMS) analysis, in which sodium filament growth within voids and along grain boundaries is observed, contributing to the sodium network formation potentially leading to failure of batteries

Kinetics and Pore Formation of the Sodium Metal Anode on NASICON‐Type Na₃.₄Zr₂Si₂.₄P₀.₆O₁₂ for Sodium Solid‐State Batteries

In recent years, many efforts have been made to introduce reversible alkali metal anodes using solid electrolytes in order to increase the energy density of next‐generation batteries. In this respect, Na₃.₄Zr₂Si₂.₄P₀.₆O₁₂ is a promising solid electrolyte for solid‐state sodium batteries, due to its high ionic conductivity and apparent stability versus sodium metal. The formation of a kinetically stable interphase in contact with sodium metal is revealed by time‐resolved impedance analysis, in situ X‐ray photoelectron spectroscopy, and transmission electron microscopy. Based on pressure‐ and temperature‐dependent impedance analyses, it is concluded that the Na|Na₃.₄Zr₂Si₂.₄P₀.₆O₁₂interface kinetics is dominated by current constriction rather than by charge transfer. Cross‐sections of the interface after anodic dissolution at various mechanical loads visualize the formed pore structure due to the accumulation of vacancies near the interface. The temporal evolution of the pore morphology after anodic dissolution is monitored by time‐resolved impedance analysis. Equilibration of the interface is observed even under extremely low external mechanical load, which is attributed to fast vacancy diffusion in sodium metal, while equilibration is faster and mainly caused by creep at increased external load. The presented information provides useful insights into a more profound evaluation of the sodium metal anode in solid‐state batteries

The Impact of Microstructure on Filament Growth at the Sodium Metal Anode in All‐Solid‐State Sodium Batteries

In recent years, all‐solid‐state batteries (ASSBs) with metal anodes have witnessed significant developments due to their high energy and power density as well as their excellent safety record. While intergranular dendritic lithium growth in inorganic solid electrolytes (SEs) has been extensively studied for lithium ASSBs, comparable knowledge is missing for sodium‐based ASSBs. Therefore, polycrystalline Na‐β″‐alumina is employed as a SE model material to investigate the microstructural influence on sodium filament growth during deposition of sodium metal at the anode. The research focuses on the relationship between the microstructure, in particular grain boundary (GB) type and orientation, sodium filament growth, and sodium ion transport, utilizing in situ transmission electron microscopy (TEM) measurements in combination with crystal orientation analysis. The effect of the anisotropic sodium ion transport at/across GBs depending on the orientation of the sodium ion transport planes and the applied electric field on the current distribution and the position of sodium filament growth is explored. The in situ TEM analysis is validated by large field of view post‐mortem secondary ion mass spectrometer (SIMS) analysis, in which sodium filament growth within voids and along grain boundaries is observed, contributing to the sodium network formation potentially leading to failure of batteries

Sequential vs. Simultaneous Trust

We examine theoretically and experimentally the implications of trust arising under sequential and simultaneous designs, where one player makes an investment choice, and another player decides whether to share the investment gains. We show analytically that in some cases the sequential design may be outperformed by the simultaneous design. In an experiment we find that the investment levels and sharing rates are higher in the sequential design, but there are no corresponding differences in beliefs. We conjecture that this happens because in the sequential design substantially more trust is necessary to induce cooperation. Our data strongly support this conjecture

Deposition of sodium metal at the copper‐NaSICON interface for reservoir‐free solid‐state sodium batteries

"Anode-free" solid-state battery concepts are explored extensively as they promise a higher energy density with less material consumption and simple anode processing. Here, the homogeneous and uniform electrochemical deposition of alkali metal at the interface between current collector and solid electrolyte plays the central role to form a metal anode within the first cycle. While the cathodic deposition of lithium has been studied intensively, knowledge on sodium deposition is scarce. In this work, dense and uniform sodium layers of several microns thickness are deposited at the Cu|Na3.4Zr2Si2.4P0.6O12 interface with high reproducibility. At current densities of approximate to 1 mA center dot cm-2, relatively uniform coverage is achieved underneath the current collector, as shown by electrochemical impedance spectroscopy and 3D confocal microscopy. In contrast, only slight variations of the coverage are observed at different stack pressures. Early stages of the sodium metal growth are analyzed by in situ transmission electron microscopy revealing oriented growth of sodium. The results demonstrate that reservoir-free ("anode-free") sodium-based batteries are feasible and may stimulate further research efforts in sodium-based solid-state batteries. The cathodic deposition of sodium at the Cu|Na3.4Zr2Si2.4P0.6O12 interface aiming for "reservoir-free" sodium solid-state batteries is studied systematically. Dense and roughly 10 mu m thick sodium layers are formed underneath the copper current collector. By increasing the current density j during deposition, a higher coverage is obtained, while the stack pressure has only a minor influence on the coverage.imag

Data for Publication "Deposition of Sodium Metal at the Copper-NaSICON Interface for Reservoir-free Solid-State Sodium Batteries"

<p><strong>Description:</strong> The data set consists of series of measurements from electrochemical impedance spectroscopy (EIS), optical microscopy, 3D confocal microscopy, focused ion beam - scanning electron microscopy (FIB-SEM), and in situ scanning transmission electron microscpy (STEM) to characterize sodium metal deposition at the Cu|NaSCION interface. The data set presented serves as the basis for the following publication:</p><p><strong>Title:</strong> Deposition of Sodium Metal at the Copper-NaSICON Interface for Reservoir-free Solid-State Sodium Batteries</p><p><strong>Authors:</strong> Till Ortmann, Till Fuchs, Janis K. Eckhardt, Ziming Ding, Qianli Ma, Frank Tietz, Christian Kübel, Marcus Rohnke, Jürgen Janek</p><p><strong>DOI:</strong> https://doi.org/10.1002/aenm.202302729 </p><p>"Anode‐free" solid‐state battery concepts are explored extensively as they promise a higher energy density with less material consumption and simple anode processing. Here, the homogeneous and uniform electrochemical deposition of alkali metal at the interface between current collector and solid electrolyte plays the central role to form a metal anode within the first cycle. While the cathodic deposition of lithium has been studied intensively, knowledge on sodium deposition is scarce. In this work, dense and uniform sodium layers of several microns thickness are deposited at the Cu|Na3.4Zr2Si2.4P0.6O12 interface with high reproducibility. At current densities of ≈1 mA∙cm−2, relatively uniform coverage is achieved underneath the current collector, as shown by electrochemical impedance spectroscopy and 3D confocal microscopy. In contrast, only slight variations of the coverage are observed at different stack pressures. Early stages of the sodium metal growth are analyzed by in situ transmission electron microscopy revealing oriented growth of sodium. The results demonstrate that reservoir‐free ("anode‐free") sodium‐based batteries are feasible and may stimulate further research efforts in sodium‐based solid‐state batteries. </p><p>Abstract from: https://doi.org/10.1002/aenm.202302729 </p&gt

Kinetics and Pore Formation of the Sodium Metal Anode on NASICON‐Type Na 3.4 Zr 2 Si 2.4 P 0.6 O 12 for Sodium Solid‐State Batteries

In recent years, many efforts have been made to introduce reversible alkali metal anodes using solid electrolytes in order to increase the energy density of next-generation batteries. In this respect, Na3.4Zr2Si2.4P0.6O12 is a promising solid electrolyte for solid-state sodium batteries, due to its high ionic conduc-tivity and apparent stability versus sodium metal. The formation of a kinetically stable interphase in contact with sodium metal is revealed by time-resolved impedance analysis, in situ X-ray photoelectron spectroscopy, and transmis-sion electron microscopy. Based on pressure- and temperature-dependent impedance analyses, it is concluded that the Na|Na3.4Zr2Si2.4P0.6O12 interface kinetics is dominated by current constriction rather than by charge transfer. Cross-sections of the interface after anodic dissolution at various mechanical loads visualize the formed pore structure due to the accumulation of vacancies near the interface. The temporal evolution of the pore morphology after anodic dissolution is monitored by time-resolved impedance analysis. Equilibration of the interface is observed even under extremely low external mechanical load, which is attributed to fast vacancy diffusion in sodium metal, while equilibra-tion is faster and mainly caused by creep at increased external load. The pre-sented information provides useful insights into a more profound evaluation of the sodium metal anode in solid-state batteries

The impact of microstructure on filament growth at the sodium metal anode in all‐solid‐state sodium batteries

In recent years, all‐solid‐state batteries (ASSBs) with metal anodes have witnessed significant developments due to their high energy and power density as well as their excellent safety record. While intergranular dendritic lithium growth in inorganic solid electrolytes (SEs) has been extensively studied for lithium ASSBs, comparable knowledge is missing for sodium‐based ASSBs. Therefore, polycrystalline Na‐β″‐alumina is employed as a SE model material to investigate the microstructural influence on sodium filament growth during deposition of sodium metal at the anode. The research focuses on the relationship between the microstructure, in particular grain boundary (GB) type and orientation, sodium filament growth, and sodium ion transport, utilizing in situ transmission electron microscopy (TEM) measurements in combination with crystal orientation analysis. The effect of the anisotropic sodium ion transport at/across GBs depending on the orientation of the sodium ion transport planes and the applied electric field on the current distribution and the position of sodium filament growth is explored. The in situ TEM analysis is validated by large field of view post‐mortem secondary ion mass spectrometer (SIMS) analysis, in which sodium filament growth within voids and along grain boundaries is observed, contributing to the sodium network formation potentially leading to failure of batteries