We report the plating and stripping of calcium metal at room temperature in a mixture of ethylene carbonate (EC) and propylene carbonate (PC) solvents using calcium tetrafluoroborate (Ca­(BF4)2) as the salt. Calcium is reversibly deposited and removed over several cycles, with associated plating–stripping efficiencies of >95%. Thin layers (∼20 μm) of crystalline calcium are present as the deposits, with a stable solid electrolyte interface (SEI) forming. This work opens opportunities to realize redox active Ca metal electrodes using commercially available alkyl carbonate solvents.

Calcium batteries are an emerging, next generation energy storage technology undergoing intense research toward viable operation. A key aspect in their development is plating and stripping of a calcium metal anode in suitable electrolytes. Herein, we report that calcium can be plated and stripped at room temperature in an ionic-liquid-based electrolyte. Thick continuous deposits (∼20 μm) of crystalline calcium are plated and stripped over 10 cycles to areal capacities of 2.2 mAh cm −2 at a current density of 0.56 mA/cm 2 . This work presents ionic liquids as viable electrolytes for calcium anodes to enable redox activity for calcium batteries.

We report a study on the growth kinetics and resultant structures of arrays of pillars in photo-cross-linkable films during irradiation with a periodic array of microscale optical beams under ambient conditions. The optical beams experience a self-focusing nonlinearity owing to the photopolymerization-induced changes in refractive index, thereby concentrating light and driving the concurrent, parallel growth of microscale pillars along their path length. We demonstrate control over the pillar spacing and pillar height with the irradiation intensity, film thickness, and the size and spacing of the optical beams. The growth of individual pillars in a periodic array arises from the combination of intense irradiation in the beam regions and oxygen inhibition afforded by the open, ambient conditions under which growth is carried out. We propose a kinetic model for pillar growth that includes free-radical generation and oxygen inhibition in thick films of photoinitiated media in order to interpret the experimental results. The model effectively correlates micropillar array structure to the oxygen inhibition effects. This approach of growing micropillar arrays through photopolymerization is straightforward and scalable and opens opportunities for the design of textured surfaces for applications.

Calcium-ion batteries are promising alternatives for post-lithium-ion batteries. However, their progress remains limited by challenges associated with the development of stable and effective electrolytes. We report for the first time an ionic liquid polymer gel membrane as both the electrolyte and the separator for use in a calcium-ion battery operating at room temperature. The membrane is prepared via single-step photo-cross-linking of poly(ethylene glycol) diacrylate in the presence of calcium salt dissolved in an ionic liquid and shows room temperature ionic conductivities between 10 −4 and 10 −3 S/cm, ∼4 V stability vs Ca/ Ca 2+ , a cationic transference number of 0.17, high thermal stability up to ∼300 °C, and full dissociation of the calcium salts in the ionic liquid. A prototype battery demonstrates intercalation-based room-temperature operation, delivering a promising initial discharge capacity of ∼140 mAh/g.

The fabrication of a new type of solar cell encapsulation architecture comprising a periodic array of step-index waveguides is reported. The materials are fabricated through patterning with light in a photoreactive binary blend of crosslinking acrylate and urethane, wherein phase separation induces the spontaneous, directed formation of broadband, cylindrical waveguides. This microstructured material efficiently collects and transmits optical energy over a wide range of entry angles. Silicon solar cells comprising this encapsulation architecture show greater total external quantum efficiencies and enhanced wide-angle light capture and conversion. This is a rapid, straightforward, and scalable approach to process light-collecting structures, whereby significant increases in cell performance may be achieved.