Dilatometric Investigation of Si-Rich Contacting Anode Under External Pressure

Abstract

Silicon with high abundance and high gravimetric capacity around 3579 mAh.g-1 at Li15Si4 fully lithiated state [1] is one of the attractive anode materials in lithium-ion batteries. Volume expansion of around 300% in the fully intercalated state is the Achilles’ heel of silicon, causing particle pulverisation, continuous formation of solid electrolyte interface (SEI), loss of electrical contact and capacity loss.[2] The use of silicon composite instead of pure silicon, [1,3] limited de/lithiation,[4] and boosting the electrical connection between particles by applying optimal external pressure[5] are practical solutions to mitigate these disadvantages. This study investigates the electrochemical performance and the dilatometric behaviour of a multilayer pouch cells (0.06 to 1.5 Ah) under the external mechanical pressure. Using 1/3 of the Si capacity in order to stabilise the electrochemical performance of a high silicon content anode (70 wt% Si). An irreversible electrode expansion of about 20% after 3 cycles of formation at 0.1C and a 75% electrode thickening after 200 cycles at 0.5C were observed.