Roll‐to‐roll manufacturing method of aqueous‐processed thick LiNi _0.5 Mn _0.3 Co _0.2 O ₂ electrodes for lithium‐ion batteries

Abstract

Aqueous-based slurry media for cathode electrode production offers a cleaner and safer environment during the electrode manufacturing step compared with the conventional organic solvent-based method used in the lithium-ion battery industry. In this work, carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and poly(ethylene oxide) (PEO) water-based binders are used to prepare LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC) cathode electrode. Detail electrochemical analysis reveals that the optimum mass ratio of CMC:SBR mixture is 1:2 when preparing an aqueous slurry for the NMC electrode. To mitigate particle cracking phenomenon during electrode drying step and obtain higher mass loading, a multi-layer coating technique is implemented. CMC-PEO binder mixture in aqueous media is also studied as an alternative aqueous processing method for NMC electrodes. The electrodes prepared with CMC-PEO mixture are demonstrated to be all crack-free, and electrochemical results indicate that the optimum mass loading of NMC electrode is between 15 and 18 mg cm À2 . This method is further tested in pouch cell format using a roll-to-roll pilot-scale production line to show the feasibility for commercial applications. Remarkably, pouch cell results manifest that aqueous-processed NMC cathode against graphite anode maintains its 89% capacity at 1C even after 1000 cycles. Highlights• Water-based binders of carboxymethyl cellulose-poly(ethylene oxide) provide excellent cycling stability for LiNi 0.5 Mn 0.3 Co 0.2 O 2 electrode.• Multilayer coating allows electrodes for higher loadings without any crack formation.• The water-based electrode preparation method is validated by pilot scale roll-to-roll electrode production line.

Unlocking sustainable power: advances in aqueous processing and water-soluble binders for NMC cathodes in high-voltage Li-ion batteries

“…This performance was comparable to that of PVDF-cells, which achieved 90% retention under identical conditions, albeit using toxic NMP instead of water as the solvent. 137 Cui et al employed a combination of lithium carboxymethyl cellulose (Li-CMC) and a commercial polyacrylic latex copolymer (306F) to enhance lithium conduction and improve the mechanical strength in the aqueous processing of cylindrical batteries with a nominal capacity of 2000 mA h. To address the challenge of aluminium collector corrosion, the authors used boric acid to maintain the slurry pH within the range of 9.0-10.0. This hybrid Li-CMC-306F binder exhibited superior adhesion properties attributed to the formation of hydrogen bonds, resulting in an impressive capacity retention of 88.9% aer 1200 cycles at 1C, compared to 80.6% for organic PVDF-cell under identical conditions.…”

“…This performance was comparable to that of PVDF-cells, which achieved 90% retention under identical conditions, albeit using toxic NMP instead of water as the solvent. 137…”

Do eco-friendly binders affect the electrochemical performance of MOF@CNT anodes in lithium-ion batteries?

“…30 In addition, CMC-Na is approximately one-tenth the cost of the commonly-used PVDF binder 25 and they are water-soluble which makes a clean and safe environment to produce batteries. 31 The traditional binder, PVDF, is soluble in organic solvents ( N -methyl pyrrolidone) which are expensive, flammable, and toxic. Fluoride in PVDF tends to react with the Li metal or lithiated graphite and form stable LiF and unsaturated >CCF– bonds at elevated temperatures.…”

From Lab to Manufacturing Line: Guidelines for the Development and Upscaling of Aqueous Processed NMC622 Electrodes

“…With all this, during the preparation of the electrode slurry, the cost of the PVDF dispersion in organic solvent (around 5$/kg) is much higher than the dispersion of water-based binders (1$/kg), such as the carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR). 13 While the drying and solvent recovery system of NMP contribute to 3.4% of the battery pack costs, 14,15 not only there is no cost related with the solvent recovery for aqueous processing, but also the drying step is 4.5 times faster than for NMP and requires nearly 10 times less overall energy. 16 In fact, previous studies reported more airflow rate and higher temperature during the drying step for organic-based electrodes.…”

“…12,14 In addition, further savings for capital equipment purchasing can be generated with water-based electrode production since, unlike for combustible solvent NMP, it will not require explosion-proof slurry mixers. 13 All in all, turning from the classical organic processing route to the more environmentally friendly aqueous route can lead to a decrease of 80% in the electrode fabrication costs. 12 However, upscaling the aqueous processing technique for electrode fabrication is not as straightforward as one can imagine.…”