Flexible solid-state Zn-air battery based on polymer-oxygen-functionalized g-C3N4 composite membrane

Personalized healthcare devices require an energy storage system that is flexible and has good mechanical strength and stability for long periods. Zn-air batteries show promise as an alternative to Li-air batteries for this purpose. Zn-air batteries with a high theoretical specific energy density of 1350 W h kg-1 have the potential to replace other metal-air batteries but faces the challenges, such as dendrite formation and Zn corrosion, hindering their successful commercialization. In this work, we report the design and performance optimization of a solid-state flexible Zn-air battery with superior performance and good mechanical property. In addition, we focused on the development of a gel-polymer composite membrane as the electrolyte. The main advantage of the flexible electrolyte is its optimum combination of good ionic conductivity and mechanical strength. Thus, we attempted to address the above-mentioned issues by modifying poly(vinyl alcohol) (PVA) with o-g-C3N4 through the in situ formation of a composite. The interaction between the functional groups of o-g-C3N4 and PVA increased the conductivity without compromising the mechanical behavior of the composite. According to the optimization of the composite composition, it was concluded that 0.32 wt% o-g-C3N4 in PVA showed the highest conductivity and excellent mechanical strength (increase from 25 MPa for pristine PVA membrane to 35 MPa for g-C3N4-PVA composite membrane). The performance of the solid-state battery was better (40 hours) than the standard PVA KOH (13 hours) membrane. Moreover, the stability of the battery was retained at various bending angles, demonstrating its potential to be used in flexible electronic devices.

Photo-Assisted Metal-Air Batteries: Recent Progress, Challenges and Opportunities

To meet the need of high energy density, long durability, safe and cost-efficient energy conversion and storage devices, metal-air batteries like Li-O₂ and Zn-O₂ batteries have received enormous attention and were subject to exciting development in the past decade. Photo-assisted strategies that enable the effective combination of photo/electric energy conversion/storage render a new dimension for the conventional metal-air batteries techniques with mere electric energy utilization. Therefore, tremendous research is ongoing in search of more efficient and durable devices with photo-assisted strategies. This review provides an overview of photo-assisted Li-O₂ batteries, Zn-O₂ batteries, and batteries with various metal/air components. The working mechanism, the basic device architecture and practical performances of various photo-assisted systems are summarized and discussed. Furthermore, certain technical challenges and future opportunities for the photo-assisted metal air batteries are emphasized and discussed in the hope of stimulating further research.

Photo-Charging a Zinc-Air Battery Using a Nb2O5-CdS Photoelectrode

Integrating a photoelectrode into a zinc-air battery is a promising approach to reducing the overpotential required for charging a metal-air battery by using solar energy. In this work, a photo-fuel cell employing a Nb2O5/CdS photoanode and a Zn foil as a counter-electrode worked as a photoelectrochemical battery that saves up to 1.4 V for battery charging. This is the first time a Nb2O5-based photoelectrode is reported as a photoanode in a metal-air battery, and the achieved gain is one of the top results reported so far. Furthermore, the cell consumed an organic fuel, supporting the idea of using biomass wastes as a power source for sunlight-assisted charging of metal-air batteries. Thus, this device provides additional environmental benefits and contributes to technologies integrating solar energy conversion and storage.