Electrochemical performance of melt impregnated lithium sulphur rechargeable cell: Effect of crosslinked water soluble polyacrylic acid binder

Abstract

Commercial lithium-ion batteries generate significant carbon footprint during the procurement of relatively scarce raw materials of Li, Co, Ni etc, manufacturing of cell, and their recycling. Lithium – sulphur battery is far more environmentally friendly as it uses only scarce lithium, has significantly higher specific energy density than Li ion cells, and easier to recycle. A facile one step scalable process has been developed to increase the loading and conductivity of sulphur; retard long chain polysulphides shuttling, tackle volumetric fluctuation of active particles and inhibit the lithium anode corrosion together with its dendritic growth during discharge – charge cycles. Electrode with EA-PAA binder delivers discharge capacity ∼836 mAh/g at 0.2C which is significantly larger than electrode made with PAA binder (∼745 mAh/g). At 1C rate electrode with EA-PAA binder delivers a discharge capacity ∼418 mAh/g which is significantly larger than electrode made using PAA binder (∼257 mAh/g). Irrespective of measured current, electrode with EA-PAA binder yields superior coulombic efficiency than electrode made using PAA binder. It is argued that the developed S/C composite with rGO additive and EA-PAA binder yields polar – polar interaction between EA-PAA binder and soluble long chain polysulphides to retard their shuttling. The EA-PAA binder with polar functional groups also have stronger bonding with underlying Al current collector. The stretchable EA-PAA binder network efficiently buffer the volumetric strain during alloying and de – alloying reactions as compare to PAA electrode. For S/C composite electrode, capacity fading during repeated cycling is thought to be related to the slower transformation kinetics of long chain polysulphides to insulating short chain lithium sulphides end product.