Aqueous rechargeable energy storage devices with flexible and wearable features have conceived great attention to fulfil the safe and portable energy supply .¹ Revolution in electric mobility appliances, the Internet of things, and wearable electronics² have created a big demand for the replacement of lithium-based batteries to circumvent safety, flexibility, and cost-effectiveness. The aqueous zinc-ion batteries stand upfront in terms of flexible devices that nearly competing or will be replacing the costlier lithium-ion batteries and are emerging as potential battery devices, but the limited energy density of cathodes that rely on intercalation mechanism and low voltage output of aqueous electrochemistry is a big loophole to make its success in the market.^3,4

The recently developed aqueous Zn-S batteries show enormous potential as a sustainable and cost-effective energy storage technology.⁵ With their great energy density, safety, and environmental friendliness, they have the potential to transform a variety of sectors, including renewable energy storage and electric vehicles. Instead of intercalation-type storage, these devices use a one-step solid-solid chemical transition to maximize material use.⁶ Nonetheless, these batteries have significant challenges because of the intrinsic insulating property of S and the resulting equivalent ZnS, which exhibit slow kinetics for reversible conversions and create byproducts throughout the process resulting in poor stability. While there are obstacles to overcoming this problem, current research and development activities aim to unleash the full potential of aqueous Zn-S batteries, bringing us closer to a cleaner and more efficient energy future.

As a contribution to the Zn-S battery revolution, developing a flexible Zn-S battery with high performance. Herein, we introduced and prepared a flexible Zn-S battery using S@Ti₃C₂T_x as a cathode and amphiphilic gel electrolyte. The 2D morphology and metallic property of Ti₃C₂T_x offer conductive confinement to the sulfur cathode for improved Zn-S conversion kinetics and faster diffusion paths to the zinc ions. On the other hand, the amphiphilic nature of electrolyte helps to develop robust interfaces with electrodes and restricts the shuttle of catalytic iodide additive species so they can benefit from regulated self-discharge. The as-fabricated Zn-S battery with S@Ti₃C₂T_x cathode offers high power capacity, good cycling stability, and excellent capacity retention upon multiple bending modes. To demonstrate a real application, the Zn-S batteries were connected in series to power a digital clock, red-light-emitting diode, and robot to provide a steady power supply in various deformations. To the best of our knowledge, this is an exclusive demonstration of Ti₃C₂T_x-assisted flexible Zn-S (aqueous) battery has been reported. To find the scientific insight for confinement contribution of Ti₃C₂T_x and the role of amphiphilic gel electrolyte in Zn-S battery, please read our full paper " Flexible aqueous Zn-S battery based on an S-decorated Ti₃C₂T_x Cathode" published in npj 2D mater. Appl. 7, 45 (2023). https://doi.org/10.1038/s41699-023-00411-2 

 References

[1] Song, W.-J. et al. Recent progress in aqueous based flexible energy storage devices, Energy Storage Mater. 30, 260-286 (2020).

[2] Tian, Y. et al. Promises and Challenges of Next-Generation “Beyond Li-ion” Batteries for Electric Vehicles and Grid Decarbonization, Chem. Rev. 121, 1623–1669 (2021).

[3] Liu, Y. et al. Rechargeable aqueous Zn-based energy storage devices, Joule, 5, 2845-2903 (2021).

[4] Dong, H. et al. Insights on Flexible Zinc-Ion Batteries from Lab Research to Commercialization, Mater. 33, 2007548 (2020).

[5] Li, W., Wang, K. & Jiang, K. A low cost aqueous Zn-S battery realizing ultrahigh energy density. Sci. 7, 2000761 (2020).

[6] Liu, J. et al. Sulfur-based aqueous batteries: electrochemistry and strategies. Am. Chem. Soc. 143, 15475–15489 (2021).