The Institute of Metals of the Chinese Academy of Sciences has discovered a vacancy induced ultra-fast ion transfer in two-dimensional th

On October 30, Science, an international academic journal, published online the latest progress in two-dimensional material properties of advanced Carbon Materials Research Department, Shenyang National Research Center for Materials Science, Institute of Metals, Chinese Academy of Sciences. CdPS3 nanosheets-based membrane with high proton conductivity enabled by Cd vacancies”. 

Ion transfer in nanometer channels is critical for energy storage and conversion applications. For example, proton and lithium ion conduction membranes are the key materials for fuel cells and lithium ion batteries respectively.Nafion membrane produced by dupont is currently the most commonly used commercial proton conducting membrane. 

It takes sulfonic acid group as the center of proton donor and conducts proton conduction through a network of water molecules formed in nano-pore channels, with proton conductivity up to 0.2s /cm.However, at high temperatures (>80 oC) and/or low humidity, the performance is severely attenuated due to reduced water content.In recent years, a variety of proton conducting membranes have been developed, including membrane materials based on MOF, biomaterials and go.These membrane materials also use functional groups (such as phosphoric acid group, carboxyl group, hydroxyl group, etc.) as proton donor centers, but their performance is still far from that of Nafion membrane.

Recently, Ren Wencai and Cheng Huiming from the Shenyang National Research Center for Materials Science prepared a kind of membrane composed of two-dimensional transition metal phosphor sulfide (MPX3, where M=Cd, Mn, Fe, Co, Ni, Zn, Cr, X=S or Se) nanoscale sheets, and found that transition metal vacancy makes this kind of membrane have ultra-fast ion transport performance.For example, Cd0.85 PS3li0.15H0.15 thin film is the ionic conductor dominated by proton transmission, and its conductivity is as high as 0.95s /cm under the conditions of 90℃ and 98% relative humidity, which is the highest performance of the water-phase proton transmission materials reported so far, and it still maintains a high proton conductivity under the conditions of low temperature and low humidity.

Further study found that Cd vacancy not only provides a large number of proton donor centers, but also enables the film to have excellent hydration properties, and the protons are easy to desorption from the vacancy in the presence of water molecules, thus making the film exhibit excellent proton conduction characteristics.In addition, they also found that Cd0.85 PS3LI0.3 and Mn0.77 PS3li0.46 films have ultra-fast lithium ion conduction characteristics, proving the universality of fast vacancy induced ion transport.

The rapid transfer of vacancy induced ions provides a new idea for the design and development of high-performance ion conducting membranes.Perspective, published "Science" in the same period, with the Speeding protons with metal vacancies "title of the work are introduced.