Effect of carbon black properties on dry electrode processing of cathodes for lithium-ion batteries

Abstract

Dry electrode processing of lithium-ion battery electrodes is one of the most promising technologies under development today to markedly reduce manufacturing costs of battery cells and to allow a sustainable production process in comparison to today's conventional wet electrode coating. A roll-to-roll dry coating calendar process, which uses polytetrafluoroethylene as an electrode binder, shows the greatest potential for a next-generation large-scale battery production. This work investigates the influence of carbon black additives having different physicochemical properties on the calendering step during coating process and the properties of electrodes produced as such. The carbon blacks, the composite granule intermediates and electrodes were characterized in view of mechanical and electronic properties. Single layer pouch cells were assembled to study the electrochemical characteristics. Aging tests revealed a capacity retention of 94 % after 450 cycles at C/2 for the best carbon black material being used. This work demonstrated that carbon blacks act not only as a conductive additive but also as a process aid for the calendering step, influencing the compressibility of the composite granules, resulting in adapted process parameters. Consequently, tailored carbon black properties are required to adapt electrode materials for dry coating for further improvement of this technology.