A research group led by JIANG Ying from Peking University and Academician WANG Enge from the Chinese Academy of Sciences, using a self-developed combined scanning tunnelling microscopy and noncontact atomic force microscopy system, achieved for the first time atomic scale images of sodium ion (Na⁺) hydrates, and found the hydration-number effect of their mobility, which has great application prospects in ion batteries, seawater desalination and life sciences. The study was published in Nature on May 14, 2018.