Hierarchically designed SiOx /SiOy rolled-up bilayer nanomembranes are used as anodes for lithium-ion batteries. The functionalities of the SiO(x,y) layers can be engineered by simply controlling the oxygen content, resulting in anodes that exhibit a reversible capacity of about 1300 mA h g(-1) with an excellent stability of over 100 cycles, as well as a good rate capability.

Mesoporous MnO2 nanosheet arrays have been directly grown on nickel foam current collectors and exhibited a reversible capacity as high as 1690 mA h g(-1) even after one hundred cycles at 100 mA g(-1). They also reveal good rate capability and excellent cycling stability.

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Separator membranes based on poly(vinylidene fluoride), PVDF, poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, poly(vinylidene fluorideco-hexafluropropylene), PVDF-HFP and poly(vinylidene fluoride-cochlorotrifluoroethylene), PVDF-CTFE were prepared by solvent casting method using N,N-dimethylformamide (DMF) as solvent. In all cases, the same polymer/solvent ratio and solvent evaporation temperature were used. For all membranes, porous microstructure is achieved with a degree of porosity larger than 50%. The β-phase content as well as degree of crystallinity were different for each membrane, which were lower for the co-polymer membranes when compared with PVDF. On the other hand, the observed ionic conductivity values, electrolyte uptake, tortuosity and MacMullin number were similar for all membranes. The electrochemical performance of the separator membranes was evaluated in Li/C-LiFePO4 half-cell configuration showing good cyclability and rate capability for all membranes. Among the all separator membranes, PVDF-TrFE demonstrate the best electrochemical performance, with a discharge capacity value of 87 mAh.g-1 after 50 cycles with a capacity retention of 78 % at 2C. Finally, the correlation between the β-phase content in the membranes and the cycling performance was demonstrated (which was significant at high-C rates): larger β-phase contents, leading higher polarity, facilitates faster lithium ion migration within the separator for similar microstructures.

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