Critical electrode properties and drying conditions causing component segregation in graphitic anodes for lithium-ion batteries

Westphal, Bastian; Kwade, Arno

doi:10.1016/j.est.2018.06.009

Cited by 86 publications

(104 citation statements)

References 39 publications

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“…The electrode shows no binder gradients, but an even distribution over the entire electrode height. This is a great advantage of this method compared with wet coating because even a rapid hot process cannot lead to an internal segregation …”

Section: Resultsmentioning

confidence: 99%

Solvent‐Free Manufacturing of Electrodes for Lithium‐Ion Batteries via Electrostatic Coating

et al. 2019

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This work demonstrates the feasibility of a novel solvent‐free anode production for lithium‐ion batteries. It combines a modified dry‐mixing procedure with an innovative electrostatic coating process. The mixing is divided into two steps. At first, carbon black and binder are deagglomerated and recombined to a matrix structure by intensive mixing. In a second less intensive step, this matrix is blended with graphite. The powder mixture is fluidized and then transferred to the current collector by inducing a high voltage. After a subsequent hot pressing step, the powder coating is permanently fixed on the current collector. This procedure is presented with three different fluorinated binders. Furthermore, effects of different mixing intensities on the powder and electrode properties are examined. The electrodes are investigated in the three‐electrode T‐cell setup versus lithium metal to examine their C‐rates and cycle stabilities. The produced anodes offer comparable electrochemical performance to conventional wet‐coated ones on electrode and cell levels. Overall, this new process is a suitable alternative to the conventional electrode production techniques.

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Section: Resultsmentioning

confidence: 99%

Solvent‐Free Manufacturing of Electrodes for Lithium‐Ion Batteries via Electrostatic Coating

et al. 2019

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“…To ensure a planar, homogenous electrical contact, the sample was then pressed slightly by a mechanical testing machine increasing the nominal stress up to a maximum of 0.4 MPa. Further information is given by Haselrieder et al and Westphal et al…”

Section: Methodsmentioning

confidence: 99%

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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“…Baunach et al [98] reported that for 85-µm-thick graphite anodes, lower drying temperatures (55 • C) were favoured over higher drying temperatures (110 and 195 • C) and concluded that superior current collector adhesion and particle cohesion was achieved partly due to a preferable binder distribution. Contrary to this, other research has observed an adhesion force peak when drying anodes at 155 • C [93] and 110 • C [171]. The same inversely proportional trend between adhesion strength and drying rate is reported for cathodes [97], and the migration of components during drying has been studied extensively within the last decade [52,54,97,164,172].…”

Section: The Convective Drying Parameters and The Resulting Electrochemical Performancementioning

confidence: 75%

“…The influence of temperature on electrode quality has shown a non-linear trend. Westphal et al [171] reported that a low drying temperature of 80 • C does not provide significant internal mass flow, and a small binder gradient is observed. Other authors reported that the temperature increase (between 75 and 130 • C) negatively influences the binder distribution in electrodes [164,168].…”

Section: The Convective Drying Parameters and The Resulting Electrochemical Performancementioning

confidence: 99%

Opportunities for the State-of-the-Art Production of LIB Electrodes—A Review

Bryntesen¹,

Strømman²,

Tolstorebrov³

et al. 2021

Energies

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A sustainable shift from internal combustion engine (ICE) vehicles to electric vehicles (EVs) is essential to achieve a considerable reduction in emissions. The production of Li-ion batteries (LIBs) used in EVs is an energy-intensive and costly process. It can also lead to significant embedded emissions depending on the source of energy used. In fact, about 39% of the energy consumption in LIB production is associated with drying processes, where the electrode drying step accounts for about a half. Despite the enormous energy consumption and costs originating from drying processes, they are seldomly researched in the battery industry. Establishing knowledge within the LIB industry regarding state-of-the-art drying techniques and solvent evaporation mechanisms is vital for optimising process conditions, detecting alternative solvent systems, and discovering novel techniques. This review aims to give a summary of the state-of-the-art LIB processing techniques. An in-depth understanding of the influential factors for each manufacturing step of LIBs is then established, emphasising the electrode structure and electrochemical performance. Special attention is dedicated to the convection drying step in conventional water and N-Methyl-2-pyrrolidone (NMP)-based electrode manufacturing. Solvent omission in dry electrode processing substantially lowers the energy demand and allows for a thick, mechanically stable electrode coating. Small changes in the electrode manufacturing route may have an immense impact on the final battery performance. Electrodes used for research and development often have a different production route and techniques compared to those processed in industry. The scalability issues related to the comparison across scales are discussed and further emphasised when the industry moves towards the next-generation techniques. Finally, the critical aspects of the innovations and industrial modifications that aim to overcome the main challenges are presented.

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Critical electrode properties and drying conditions causing component segregation in graphitic anodes for lithium-ion batteries

Cited by 86 publications

References 39 publications

Solvent‐Free Manufacturing of Electrodes for Lithium‐Ion Batteries via Electrostatic Coating

Solvent‐Free Manufacturing of Electrodes for Lithium‐Ion Batteries via Electrostatic Coating

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

Opportunities for the State-of-the-Art Production of LIB Electrodes—A Review

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