image: a) Schematic illustration of ultrafluidic transport of specific K+ ions through the enzyme-gated KcsA channels in biological cell plasma membrane with ion screening and ultrafluidic transport properties; b) bioinspired membrane with defined ion channels for Zn2+ ion-sieving and ultrafluidic transport; c) ultrafluidic Zn2+ hopping path along bioinspired −ClO4 group-gated channels; d) synthesis of bioinspired channels by using a MOF-5 nanoporous material via a solvent-assisted linker exchange (SALE) process, by which −ClO4 groups are grafted onto the O-sites of the MOF-5 channels to realize expecting ion selectivity; e) electron density difference and electrostatic potential mapping of grafted MOF-ClO4 bioinspired channel structure.
Credit: ©Science China Press
This study is led by Dr. Fan Zhang, Prof. Ziqi Sun (School of Chemistry and Physics, Queensland University of Technology), Prof. Ting Liao (School of Mechanical Medical and Process Engineering, Queensland University of Technology), and Prof. Lei Jiang (School of Future Technology, University of Chinese Academy of Sciences).
Aqueous Zn-ion batteries (AZIBs) have been regarded as one of the most promising alternative energy storage devices, because of the abundant Zn reserve, the considerable capacity (820 mAh g−1), and the low redox potential (−0.76 V vs standard hydrogen electrode). Unfortunately, the undesirable Zn dendrite growth and the spontaneous side corrosion and hydrogen evolution (HER) reactions limit their practical applications. Although some strategies, such as surface electric field regulation, Zn2+ flux modulation, electrolyte and electrode innovations, etc., have been proposed to solve these issues, an approach that can simultaneously suppress the dendrite growth and side reaction issues and ensure a long lifespan operation is yet urgently needed for extending this family of energy devices into real-world practices.
In well-evolved biological cells, the plasma membrane compositing a thin layer of lipids and proteins surrounding the cell has the ability of selective permeation to allow the pass of only desired ions, such as K+, at a directional ultrafast ion flux for maintaining life activity, while preventing other ions from crossing. For potassium ion KcsA channels, the ion flux reaches 1.67 ×10−3 mol m−2 s−1. In this work, researchers proposed a strategy to realize Zn ion sieving and ultrafluidic transport but prevent the diffusion of corrosive anions. By applying a −ClO4 group grafted metal-organic framework (MOF-ClO4) to mimic the functionality of KcsA channel, a bioinspired top membrane with the characteristics of perfect selectivity and ultrafluidic transport property towards Zn2+ was fabricated. The application of bioinspired top membrane on the Zn anode realizes near-perfect ion sieving (t+ = 0.96 vs. 0.57 for reference electrode; t+ = 0.5 means no selectivity) and ultrafluidic transportation (1.9 ×10−3 mmol m−2 s−1) as those of the targeting natural ion channels, which provides high rate and cycling capacity to the batteries and eliminates the growth of dendrites and the occurrence of side reactions during the long-term service.
The team found that, with the application of bioinspired top membrane, the Zn platting is regulated into preferred horizontal (002) orientation, no matter whether the substrate is Zn or Cu. The undesired vertical Zn dendrite was avoided from piercing the separator and then circuit short.
This work provides a novel approach to achieve perfect ion-sieving and superfluidity properties of a top anode membrane with regulated ion selectivity and deposition in energy devices and offers a general approach to solve the similar issues existing in other active metal-based rechargeable batteries.
See the article:
Zn-ion ultrafluidity via bioinspired ion channel for ultralong lifespan Zn-ion battery
https://doi.org/10.1093/nsr/nwae199
Journal
National Science Review