Design and validation of an online partial and total pressure measurement system for Li-ion cells

Lundström, Robin; Berg, Erik J.

doi:10.1016/j.jpowsour.2020.229347

Cited by 38 publications

(66 citation statements)

References 28 publications

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“…The electrochemical cells and the data treatment procedure for operando measurements are described in previous publications. [16,17,32] All electrode potentials were presented relative to the Li + /Li redox couple. LiFePO 4 counter electrode was assumed to be stable at 3.43 V, since negligible polarization was expected due to the low currents used.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, our team developed an OEMS setup capable of determining not only the evolution rates of the most commonly observed gases during SEI formation, such as H 2 , CO 2 , and C 2 H 4 , but also establishing their individual contribution to the total gassing of the cell. [ 16 ] Another suitable analytical technique widely employed to study electrochemical systems in situ and operando is electrochemical quartz crystal microbalance (EQCM), which may monitor mass deposition on model electrodes during operation with unparalleled sensitivity. For instance, Aurbach and Zaban [ 6 ] studied SEI formation on model Au electrodes in contact with PC‐based electrolyte and compared how the salt composition (LiPF 6 and LiAsF 6 ) of electrolyte affect the SEI.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the Ethylene Carbonate–Propylene Carbonate Mystery with Operando Characterization

Melin

Lundström

Berg

2021

Adv Materials Inter

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The “ethylene carbonate (EC)–propylene carbonate (PC) mystery” has puzzled electrochemists for decades. Surprisingly, the minor structural difference between PC and EC, a methyl vis‐à‐vis a proton, prevents PC unlike EC to form a stable solid electrolyte interphase (SEI) on carbon (C), which along with the popularity of PC has impeded the development of Li‐ion batteries with many years. Despite several hypotheses, the fundamental reason remains debated largely due to the lack of sufficient experimental evidence. Herein, SEI formed as a result of EC and PC reductions are analyzed by two state‐of‐the‐art operando techniques, online electrochemical mass spectrometry and electrochemical quartz crystal microbalance with dissipation monitoring. Although both EC‐ and PC‐based electrolytes appear to have virtually identical reaction pathways, PC is reduced much more extensively than EC and forms a much thicker SEI. However, while the SEI derived from EC remains on the electrode, PC reduction products redissolve in the electrolyte leaving the bare C electrode behind. The presented study illustrates the complex scheme of competing electro‐/chemical reactions behind SEI formation and provides further scientific details needed to eventually form a consensus of the processes governing electrode/electrolyte interphases in Li‐ion batteries.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revisiting the Ethylene Carbonate–Propylene Carbonate Mystery with Operando Characterization

Melin

Lundström

Berg

2021

Adv Materials Inter

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“…There are recent reviews of the technique where the interested reader can find further details. [14,47] Quadrupole mass analyzers typically used in OEMS machines operate in vacuum, thus, the design of the connection of the ambient-pressure electrochemical cell and the vacuum of the mass spectrometer is critical. In the original design of DEMS/OEMS cells, as it was the case of the first cell used for the analysis of an electrolyte for lithium batteries [48] (cf.…”

Section: Xrd Analysis For Batteries and Battery Materialsmentioning

confidence: 99%

“…Figure 3). [14,50] The consequence is that the single data points are separated a few minutes from each other, which is nevertheless acceptable in most cases. The electrochemical experiment must be then designed as a very slow one, of course, examples include slow cycling voltammetry and galvanostatic experiments at rates around C/10 or less.…”

Section: Xrd Analysis For Batteries and Battery Materialsmentioning

confidence: 99%

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Nonlinear Electrochemical Analysis: Worth the Effort to Reveal New Insights into Energy Materials

Schlüter

Novák

Schröder

2022

Advanced Energy Materials

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and the effectiveness and durability of the materials applied, researchers always call for reliable and detailed knowledge of the mechanism(s) of both, main and side reactions, and especially for their kinetics. In order to gain the relevant information, a large number of methods have been proposed to characterize battery materials, battery electrodes and their interfaces, and battery cells. But when samples are taken out of the cells and analyzed later, there is a high risk of both, contamination and changes due to possible relaxation processes, and the challenge is to draw sound conclusions in respect to a "living and breathing" battery cell, i.e., to a cell under current flow (cf. Figure 1). Therefore, the so-called in situ and operando (and often online) methods are preferred. Sometimes they are the only option to collect relevant data to understand and improve materials for energy systems. [5] In many cases, results from different techniques need to be combined to obtain sound conclusions. [6,7] The terminology for the aforementioned methods shifted during the last decade and is not always consistent throughout the literature. Nowadays, the general understanding is as follows: An operando experiment means a characterization experiment in an electrochemical cell (e.g., battery, fuel cell, electrolyzer) under current flow, with either the potential or the current controlled. One of the many examples is the operando neutron powder diffraction, a technique analyzing the changes in the structure of battery materials in "real" battery cells under current flow with the help of neutron diffraction. [9] Another example is the operando X-ray photoelectron spectroscopy experiment (normally limited to vacuum-compatible cells with nonvolatile electrolytes) providing information about the changes of the chemical composition of the interfacial species with the potential. [10,11] An in situ experiment is also an experiment in a battery cell, however, the current flow is interrupted when the data are collected. An example here is the in situ X-ray absorption spectroscopy (XAS) experiment in which the cell has to be disconnected for technical reasons during the operation of the detector [7] or the tomography of energy materials by means of neutron or X-ray source. [12,13] Online techniques are understood here as either continuously or periodically analyzed samples that are taken out of the electrochemical cell. A typical example is the online (differential) electrochemical mass spectrometry (often shortened as online electrochemical mass spectrometry (OEMS)/differential electrochemical mass spectrometry (DEMS)) analyzing the volatile products of electrochemical reactions with the help of a mass spectrometer by

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Elucidating the Step‐Wise Solid Electrolyte Interphase Formation in Lithium‐Ion Batteries with Operando Raman Spectroscopy

Gogoi

Melin

Berg

2022

Adv Materials Inter

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The solid electrolyte interphase (SEI) is arguably one of the most critical components of the Li‐ion cell. Despite decades of studies of the SEI, its intrinsic complexity and the lack of suitable characterization tools still prevent a real consensus on the governing mechanisms to be reached. Herein, operando Raman spectroscopy supported by complimentary online electrochemical mass spectrometry is employed to study the SEI formation on Au in a model electrolyte based on LiClO4 in ethylene carbonate (EC). Both the electrolyte itself and cell contaminants, such as O2, CO2, and H2O, contribute in stepwise electro‐/chemical processes to the build‐up of the SEI. Effects associated with electrode/electrolyte double‐layer charging, electrode adsorbate polarization (stark effect), and SEI dissolution are discerned. Lithium carbonate and lithium oxide are identified as major products formed already ≈2 V versus Li+/Li. Although Raman spectroscopy provides deeper insights into the underlying mechanisms, complementary techniques are necessary to support spectral interpretations. Classical challenges in the field of surface science, such as contaminations, have to be systematically addressed if the puzzle of the SEI ever will be completed.

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Design and validation of an online partial and total pressure measurement system for Li-ion cells

Cited by 38 publications

References 28 publications

Revisiting the Ethylene Carbonate–Propylene Carbonate Mystery with Operando Characterization

Revisiting the Ethylene Carbonate–Propylene Carbonate Mystery with Operando Characterization

Nonlinear Electrochemical Analysis: Worth the Effort to Reveal New Insights into Energy Materials

Elucidating the Step‐Wise Solid Electrolyte Interphase Formation in Lithium‐Ion Batteries with Operando Raman Spectroscopy

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