This paper presents an experimental study of an underwater pulsed plasma discharge in pin-to-pin electrode configuration. Time resolved refractive index-based techniques and electrical measurements have been performed in order to study the pre-breakdown and breakdown phenomena in water. A single high voltage pulse with amplitude of a dozen of kV and duration of [0.1-1] ms is applied between two 100 µm diameter platinum tips separated by 2 mm. This novel experimental work reports that different cases of electrical discharge in water occurs for a unique set of experimental conditions such as (i) bush-like channels from the cathode that do not span the electrode gap, (ii) bush-like channels from the cathode leading to breakdown and (iii) filamentary structures from the anode leading to a stronger breakdown. Two breakdown mechanisms, anode and cathode regimes, have been clearly identified and related to the two principal schools of thoughts to explain discharge propagation in liquid.

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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.