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Green energy harvesting (solar and wind) and storage along with electrification of transport sector could bring about a major transformation in the CO2 emission levels that we are currently experiencing. Lithium ion batteries provide an efficient energy storage system to realize this goal. The key developments in Li-ion battery technology starting from solid solution electrodes, intercalation electrodes, conversion electrodes, organic electrodes, and polymer electrolytes with a major focus on the contribution of Michel Armand, an eminent scientist who at a young age saw the future of energy storage, have been elaborated. Moreover, the direction of research that seems interesting to pursue for realizing our goals has also been outlined.

Crosslinking of styrene grafted and sulfonated fuel cell membranes is essential to obtaining well-performing and durable membranes. The properties and fuel cell performance of radiation grafted membranes based on ETFE (25 micron) with different extent of crosslinking, using divinylbenzene (DVB) as co-monomer to styrene, was investigated. At high degrees of crosslinking, fuel cell performance was limited by the high ohmic resistance of the membrane, whereas at low degrees of crosslinking the membrane-electrode interface was of poor quality. Optimum performance was obtained at a degree of crosslinking corresponding to a styrene:DVB monomer ratio (v/v) in the grafting solution of 95:5.

In this study, the effect of cross-linker content on the chemical stability of polyethylene-alt-tetrafluoroethyleneETFE-based radiation-grafted and sulfonated membranes was investigated. An ex situ degradation test in H2O2 solution showed a strong increase in stability of cross-linked membranes compared to uncross-linked ones. Excessive cross-linking, however, is detrimental to the chemical and mechanical properties. Furthermore, the stability of grafted membranes based on ETFE was superior to those based on polytetrafluoroethylene-co-hexafluoropropyleneFEP. An in situ long-term test in a H2/O2 single cell over 2180 h, using an ETFE-based grafted membrane optimized with respect to cross-linker content, with a graft level of 25% was carried out. The performance of the membrane electrode assembly exhibited a voltage decay rate of 13 Vh 1 over the testing time at a current density of 500 mA cm 2 and a cell temperature of 80°C, while the hydrogen permeation showed a steady increase over time. This indicates that, to some extent, changes in the membrane morphology occur over the operating period. Local postmortem analysis of the tested membrane reveals that high degradation was observed in areas adjacent to the O2 inlet and in other areas nearby.

Cross-linking of styrene grafted and sulfonated fuel cell membranes is essential to obtain well-performing and durable membranes. In this study, the properties and fuel cell performance of radiation grafted membranes based on poly(ethylene-alt-hexafluoropropylene) (ETFE) (25 μm) with different extent of cross-linking, using divinylbenzene (DVB) as a comonomer to styrene, were investigated. The water uptake and proton conductivity decrease as a function of increasing the extent of cross-linking. Also, the membranes become more brittle. Fuel cell performance is limited by the high ohmic resistance of the membrane at high degrees of cross-linking, whereas at low degrees of cross-linking the membrane-electrode interface is of poor quality. Optimum performance is obtained at an extent of cross-linking corresponding to a styrene:DVB monomer ratio (v/v) of 95:5 in the grafting solution.

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