Selection and Surface Modifications of Current Collectors for Anode-Free Polymer-Based Solid-State Batteries.

Anode-free batteries (AFB) have attracted increasing interest in recent times because they allow the elimination of the conventional anode from the cell, exploiting lithium inventory from a lithiated cathode. This implies a much simpler, cost-effective, and sustainable approach. The AFB configuration with liquid electrolytes is being explored widely in research but rarely using solid electrolytes. One of the main issues of AFB is the poor reversibility of the lithium-plating/striping process at the anode side. Therefore, in this work, different metal foils have been tested as anode current collectors (CC), and copper foil has been selected as the most promising one. Surface modifications of the selected copper foil have been achieved by its coating using composite layers made of carbon and different metal nanoparticles-such as Ag, Sn, or Zn-in different proportions and with different amounts of a binder. The impact of such coatings and their thickness on the electrochemical performance of single-layer solid-state anode-free pouch cells, based on a PEO electrolyte and a LiFePO4 cathode has been systematically studied. Consequently, a post-mortem analysis of the investigated solid-state AFB is also presented, trying to identify and elucidate possible failure mechanisms to enhance the electrochemical performance of solid-state AFB in the future.

Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid).

The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid) (PLA) composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data.