Optimizing lithium battery performance from a tailor-made processing of the positive composite electrode

We studied the effect of the dispersion and/or morphology within the positive composite electrode on the lithium battery performance. Model electrodes have been prepared in which the surrounding of the same AM (Li1.1V3O8) is changed by playing with plasticization of the polymeric binder (B) (PMMA) by ethylene carbonate (EC) and propylene carbonate (PC). We have also varied the concentration, and the nature of the solvent used for the electrode elaboration (THF and CHCl3). The cycled capacity varies between 100 and 250 mA h/g (C/5 rate, 3.3–2 V) depending on these parameters. The performance was shown to depend on the quality of AM, B, and carbon black (CB) dispersion within the electrode. The quality of the AM dispersion depends on the solvent concentration that affects the mixture viscosity. Formation of AM agglomerates results from high viscosity, while gradient concentrations appear due to sedimentation in low viscosity suspensions. Optimal distribution and subsequent electrode performance result from optimal solvent concentration. Better CB dispersion was obtained in the case of favourable interactions between the solvent and the polymer. This resulted in a higher electronic conductivity, a higher porosity, and improved electrochemical performance. Finally, the addition of EC–PC also favours the CB dispersion and further increases the cycling capacity.