Investigation concerning the applicability of raman spectroscopy for prospective inline monitoring of electrode processing for lithium ion batteries

Langklotz, U.; Schneider, Michael; Seifert, Carolyn E.; Michaelis, Alexander

doi:10.1002/mawe.201100817

Cited by 8 publications

(19 citation statements)

References 19 publications

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“…Furthermore, water can get into the cell components by their remoistening in the surrounding atmosphere after the drying process during further processing, storage, transport, or cell assembly . In fact, the water absorption of the electrodes depends mostly on their active surface, atmospheric humidity, and the temperature . Comparable mechanisms to the ones occurring in the electrodes take place in the used separators.…”

Section: Introductionsupporting

confidence: 91%

“…After coating and drying, there can still remain several thousand ppm of water in the electrodes . Furthermore, water can get into the cell components by their remoistening in the surrounding atmosphere after the drying process during further processing, storage, transport, or cell assembly . In fact, the water absorption of the electrodes depends mostly on their active surface, atmospheric humidity, and the temperature .…”

Section: Introductionmentioning

confidence: 99%

“…The remaining water content in the cells is problematic as it undergoes unwanted side reactions with the conducting salt LiPF 6 , which is commonly used in organic electrolytes for LIBs . These reactions lead to the formation of gaseous hydrogen fluoride (HF) and further acidic decay products

{LiPF}_{6} + {normalH}_{2} O \to 2 HF + LiF + {POF}_{3}

…”

Section: Introductionmentioning

confidence: 99%

“…These unwanted side reactions cause various problems. The loss of conductive salt leads to a decline of the electrolyte conductivity and, correspondingly, to an increasing electrical resistance and a decreasing cell capacity . The acidic products can further cause decomposition of the active materials, e.g., by leaching of manganese in NMC cathodes .…”

Section: Introductionmentioning

confidence: 99%

“…The loss of conductive salt leads to a decline of the electrolyte conductivity and, correspondingly, to an increasing electrical resistance and a decreasing cell capacity . The acidic products can further cause decomposition of the active materials, e.g., by leaching of manganese in NMC cathodes . In addition, these compounds can hinder the formation of an effective solid electrolyte interface (SEI) or attack an already existing SEI .…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Different Post‐Drying Procedures on Remaining Water Content and Physical and Electrochemical Properties of Lithium‐Ion Batteries

2019

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The post‐drying of electrodes and separators for lithium‐ion batteries just before cell assembly aims at reducing the water content in the cells below a critical value. This is important as the remaining water can lead to cell degradation and thus cause a safety risk. In addition, it can impede the formation of an effective solid electrolyte interface. Nevertheless, the post‐drying of lithium‐ion battery electrodes and separators is still poorly investigated. Considering this, three different post‐drying procedures are investigated on pouch cells and compared with the non‐post‐dried state. The remaining water contents are measured via coulometric Karl Fischer Titration and correlated to the resulting electrochemical performance. Surprisingly, the most intensely post‐dried cells show the worst electrochemical performance despite reaching the lowest water content. In contrast, the mildest post‐dried cells, which show the highest water content, achieve the best electrochemical performance. Further analyses show that extreme post‐drying can cause irreparable damages within the electrode structures. Therefore, a good electrochemical performance is not only guaranteed by low remaining water content but also, in particular, by gentle post‐drying.

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Section: Introductionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

{LiPF}_{6} + {normalH}_{2} O \to 2 HF + LiF + {POF}_{3}

…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Influence of Different Post‐Drying Procedures on Remaining Water Content and Physical and Electrochemical Properties of Lithium‐Ion Batteries

2019

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Design of Vacuum Post‐Drying Procedures for Electrodes of Lithium‐Ion Batteries

Huttner

Marth

Eser

et al. 2021

Batteries & Supercaps

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In order to reduce the residual moisture in lithium‐ion batteries, electrodes and separators need to be post‐dried prior to cell assembly. On an industrial scale, this is often conducted batch‐wise in vacuum ovens for larger electrode and separator coils. Especially for electrodes, the corresponding post‐drying parameters have to be carefully chosen to sufficiently reduce the moisture without damaging the sensitive microstructure. This requires a fundamental understanding of structural limitations as well as heat transfer and water mass transport in coils. The aim of this study is to establish a general understanding of the vacuum post‐drying process of coils. Moreover, the targeted design of efficient, well‐adjusted and application‐oriented vacuum post‐drying procedures for electrode coils on the basis of modelling is employed, while keeping the post‐drying intensity as low as possible, in order to maintain the sensitive microstructure and to save time and costs. In this way, a comparatively short and moderate 2‐phase vacuum post‐drying procedure is successfully designed and practically applied. The results show that the designed procedure is able to significantly reduce the residual moisture of anode and cathode coils, even with greater electrode lengths and coating widths, without deteriorating the sensitive microstructure of the electrodes.

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Production of Nickel‐Rich Cathodes for Lithium‐Ion Batteries from Lab to Pilot Scale under Investigation of the Process Atmosphere

et al. 2023

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The selection of an appropriate cathode active material is important for operation performance and production of high‐performance lithium‐ion batteries. Promising candidates are nickel‐rich layered oxides like LiNixCoyMnzO2 (NCM, x+y+z=1) with nickel contents of ‘x’ ≥ 0.8, characterized by high electrode potential and specific capacity. However, these materials are associated with capacity fading due to their high sensitivity to moisture. Herein, two different polycrystalline NCM materials with nickel contents of 0.81 ≤ ‘x’ ≤ 0.83 and protective surface coatings are processed in dry‐room atmosphere (dew point of supply air TD ≈ −65 °C) at lab scale including the slurry preparation and coating procedure. In comparison, cathodes are produced in ambient atmosphere and both variants are tested in coin cells. Moreover, processing at pilot scale in ambient atmosphere is realized successfully by continuous coating and drying of the cathodes. Relevant electrode properties such as adhesion strength, specific electrical resistance, and pore‐size distribution for the individual process steps are determined, as well as the moisture uptake during calendering. Furthermore, rate capability and cycling stability are investigated in pouch cells, wherein initial specific discharge capacities of up to 190 mAh g−1 (with regard to the cathode material mass) are achieved at 0.2C.

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Investigation concerning the applicability of raman spectroscopy for prospective inline monitoring of electrode processing for lithium ion batteries

Cited by 8 publications

References 19 publications

The Influence of Different Post‐Drying Procedures on Remaining Water Content and Physical and Electrochemical Properties of Lithium‐Ion Batteries

The Influence of Different Post‐Drying Procedures on Remaining Water Content and Physical and Electrochemical Properties of Lithium‐Ion Batteries

Design of Vacuum Post‐Drying Procedures for Electrodes of Lithium‐Ion Batteries

Production of Nickel‐Rich Cathodes for Lithium‐Ion Batteries from Lab to Pilot Scale under Investigation of the Process Atmosphere

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