Gently does it!: <i>in situ</i> preparation of alkali metal–solid electrolyte interfaces for photoelectron spectroscopy

Gibson, Joshua S.; Narayanan, Sudarshan; Swallow, Jack E. N.; Thakur, P.; Pasta, Mauro; Lee, Tien‐Lin; Weatherup, Robert S.

doi:10.1039/d1fd00118c

Cited by 24 publications

(28 citation statements)

References 69 publications

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“…A very similar evolution of the P 2p spectra was observed during in situ XPS of LiPON 55 Finally, a new feature at lower BE was detected in the O 1s spectra, which grew to dominate with time and could be assigned to Li2O. Although there will be some Li2O present due to the deposited Li reacting with surface contaminants and trace O2/H2O present inside the XPS chamber, 56 it is likely that a majority of the Li2O formed as a result of direct reaction with LAPO considering the greater impedance of the interphase. Therefore, the passivation layer was found to be a mixture of Li2O, Li3P, LixP and Al 0 species.…”

Section: In Situ Xps During LI Depositionsupporting

confidence: 67%

Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

Vadhva

Gill

Cruddos

et al. 2022

Preprint

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Non-crystalline Li+-ion solid electrolytes (SEs), such as lithium phosphorous oxynitride, can uniquely enable high-rate solid-state battery operation over thousands of cycles in thin film form. However, they are typically produced by expensive and low throughput vacuum deposition, limiting their wide application and study. Here, we report a non- crystalline SE of composition Li-Al-P-O (LAPO) with an ionic conductivity >10-7 S cm-1 at room temperature by spin coating from aqueous solutions and subsequent annealing in air. Homogenous, dense, flat layers can be synthesised with sub- micron thickness at temperatures as low as 230 °C. Control of the composition is shown to significantly affect the ionic con- ductivity, with increased Li and decreased P content being optimal, while higher annealing temperatures result in decreased ionic conductivity. Activation energy analysis reveals a Li+-ion hopping barrier of 0.42(1) eV. Additionally, these SEs exhibit low room temperature electronic conductivity (<10-11 S cm-1) and moderate Young’s modulus of ≈54 GPa, which may be beneficial in preventing Li dendrite formation. In contact with Li metal, LAPO is found to form a stable, but high impedance passivation layer comprised of Al metal, Li-P and Li-O species. These findings should be of value when engineering non- crystalline SEs for Li-metal batteries with high energy and power densities.

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Section: In Situ Xps During LI Depositionsupporting

confidence: 67%

Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

Vadhva

Gill

Cruddos

et al. 2022

Preprint

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“…During the lithium diffusivity experiments, care was taken to minimize the presence of contamination at the interface between the evaporated tracer thin films and the 6 Li or 7 Li-Mg substrates. Lithium and Li-Mg alloy samples will rapidly react with trace moisture, oxygen, carbon dioxide, and nitrogen in a glovebox and even in the vacuum in the thermal evaporation chamber. , Mindful of this, exposure of the fresh lithium and Li-Mg alloy surfaces to the glovebox atmosphere was kept to a minimum (<1 min) before evacuation of the thermal evaporation chamber. However, the presence of some contamination is unavoidable, and in order to understand its effect on the lithium diffusivity, Figure a compares two diffusion profiles of 7 Li into 6 Li where the 6 Li substrate was prepared in glovebox atmospheres with different contamination levels prior to the 7 Li tracer deposition.…”

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confidence: 99%

On the Relative Importance of Li Bulk Diffusivity and Interface Morphology in Determining the Stripped Capacity of Metallic Anodes in Solid-State Batteries

et al. 2022

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Lithium metal self-diffusion is too slow to sustain large current densities at the interface with a solid electrolyte, and the resulting formation of voids on stripping is a major limiting factor for the power density of solid-state cells. The enhanced morphological stability of some lithium alloy electrodes has prompted questions on the role of lithium diffusivity in these materials. Here, the lithium diffusivity in Li-Mg alloys is investigated by an isotope tracer method, revealing that the presence of magnesium slows down the diffusion of lithium. For large stripping currents the delithiation process is diffusion-limited, hence a lithium metal electrode yields a larger capacity than a Li-Mg electrode. However, at lower currents we explain the apparent contradiction that more lithium can be extracted from Li-Mg electrodes by showing that the alloy can maintain a more geometrically stable diffusion path to the solid electrolyte surface so that the effective lithium diffusivity is improved.

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“…12 We note that recent studies suggested that dual mode charge compensating XPS instruments (such as the one employed in this study) may alter the chemistry of the interphase because of the energy provided by the impacts from Ar + ions on the surface. 15 To minimize this effect, the Ar + ion current was reduced in this study.…”

Section: Discussionmentioning

confidence: 99%

“…A recent publication demonstrated that the bombardment of the interface by Ar + ions during plating can impact the interphase composition. 15 To minimize the Ar + ion flux reaching the interface, the extractor voltage of the instrument was reduced to 30 V following the results of a previous study. 16 The Na 0 plating rate was controlled by optimizing the FG parameters: the beam voltage was set to 3 V, and the current was set to 30 μA (the actual electronic current reaching the sample surface was measured using a Faraday cup and a value of ~4.8 μA was found; the Ar + current reaching the surface is ~10 nA).The base pressure of the instrument (FG off) is typically around 1 x 10 -9 mbar and rises to around 1 x 10 -8 mbar when the FG is activated.…”

Section: X-ray Photoelectron Spectroscopy (Xps)mentioning

confidence: 99%

New insights into the kinetics of metal|electrolyte interphase growth in solid-state-batteries via an operando XPS analysis - part I: experiments

Quérel

Williams

Seymour

et al. 2022

Preprint

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To harness all the benefits of solid-state battery (SSB) architectures in terms of energy density, their negative electrode should be an alkali metal. However, the high chemical potential of alkali metals make them prone to reduce most solid electrolytes (SE), resulting in a decomposition layer called an interphase at the metal|SE interface. Quantitative information about the interphase chemical composition and rate of formation are challenging to obtain because the reaction occurs at a buried interface. In this study, a thin layer of Na metal (Na0) is plated on the surface of a SE of the NaSICON family (Na3.4Zr2Si2.4P0.6O12 or NZSP) inside a commercial XPS system whilst continuously analysing the composition of the interphase operando. We identify the existence of an interphase at the Na0|NZSP interface, and more importantly, we demonstrate for the first time that this protocol can be used to study the kinetics of interphase formation. A second important outcome of this article is that the surface chemistry of NZSP samples can be tuned to improve their stability against Na0. It is demonstrated by XPS and time-resolved electrochemical impedance spectroscopy (EIS) that a native Na3PO4 layer present on the surface of as-sintered NZSP samples protects their surface against decomposition.

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Gently does it!: in situ preparation of alkali metal–solid electrolyte interfaces for photoelectron spectroscopy

Abstract: The key charge transfer processes in energy storage devices occur at the electrode-electrolyte interface, which is typically buried making it challenging to access the interfacial chemistry. In the case of...

Cited by 24 publications

References 69 publications

Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

On the Relative Importance of Li Bulk Diffusivity and Interface Morphology in Determining the Stripped Capacity of Metallic Anodes in Solid-State Batteries

New insights into the kinetics of metal|electrolyte interphase growth in solid-state-batteries via an operando XPS analysis - part I: experiments

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