Carbon-based negative electrodes for rechargeable lithium batteries

Perkins, Mark James (2000) Carbon-based negative electrodes for rechargeable lithium batteries. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Chapter Four presents an extensive study of single cycle experiments carried out on a variety of electrode composites containing various quantities of coke, carbon fibre and carbon black conductivity additives. It has been shown that the first cycle is very important in determining the usefulness of electrode materials for multiple cycle experiments. It has also been shown that particle size and the quantity of conductivity additive within the electrode composite has a significant effect on the performance of the electrode. A new, high surface area, carbon fibre, SA86, has been studied and it has been shown that the surface area has a detrimental effect on the cycling behaviour of this material. The affect that interparticle contact has on the capacities of fibrous electrodes has been demonstrated. Scanning electron microscopy has been used to probe the degradation that these electrodes suffer during the course of the insertion-extraction cycle and a method of presenting the insertion data has been used to show regions of lithium plating.. A preliminary study of the diffusion coefficient of lithium within these electrode composites, calculated from the insertion data, has been undertaken.

Chapter Five uses the results from Chapter Four to aid in the choice of electrode composites that will be cycled a number of times. It has been shown that by raising the lower potential limit to values above the lithium plating region, cycling efficiencies of 99% can be obtained over multiple cycles. It is also evident that the better fabricated, preprepared electrodes have higher capacities and cycling efficiencies than those that have not been ball-milled.

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