Observation of Surface Atoms during Platinum Nanocrystal Growth by Monomer Attachment

Observation of Surface Atoms during Platinum Nanocrystal Growth by Monomer Attachmen

Anisotropic Lithiation Onset in Silicon Nanoparticle Anode Revealed by <i>in Situ</i> Graphene Liquid Cell Electron Microscopy

Recent real-time analyses have provided invaluable information on the volume expansion of silicon (Si) nanomaterials during their electrochemical reactions with lithium ions and have thus served as useful bases for robust design of high capacity Si anodes in lithium ion batteries (LIBs). In an effort to deepen the understanding on the critical first lithiation of Si, especially in realistic liquid environments, herein, we have engaged <i>in situ</i> graphene liquid cell transmission electron microscopy (GLC-TEM). In this technique, chemical lithiation is stimulated by electron-beam irradiation, while the lithiation process is being monitored by TEM in real time. The real-time analyses informing of the changes in the dimensions and diffraction intensity indicate that the very first lithiation of Si nanoparticle shows anisotropic volume expansion favoring the ⟨110⟩ directions due to the smaller Li diffusion energy barrier at the Si–electrolyte interface along such directions. Once passing this initial volume expansion stage, however, Li diffusion rate becomes isotropic in the inner region of the Si nanoparticle. The current study suggests that the <i>in situ</i> GLC-TEM technique can be a useful tool in understanding battery reactions of various active materials, particularly those whose initial lithiation plays a pivotal role in overall electrochemical performance and structural stability of the active materials

Real-Time Observation of Water-Soluble Mineral Precipitation in Aqueous Solution by <i>In Situ</i> High-Resolution Electron Microscopy

The precipitation and dissolution of water-soluble minerals in aqueous systems is a familiar process occurring commonly in nature. Understanding mineral nucleation and growth during its precipitation is highly desirable, but past <i>in situ</i> techniques have suffered from limited spatial and temporal resolution. Here, by using <i>in situ</i> graphene liquid cell electron microscopy, mineral nucleation and growth processes are demonstrated in high spatial and temporal resolution. We precipitate the mineral thenardite (Na₂SO₄) from aqueous solution with electron-beam-induced radiolysis of water. We demonstrate that minerals nucleate with a two-dimensional island structure on the graphene surfaces. We further reveal that mineral grains grow by grain boundary migration and grain rotation. Our findings provide a direct observation of the dynamics of crystal growth from ionic solutions

Real-Time Observation of Water-Soluble Mineral Precipitation in Aqueous Solution by <i>In Situ</i> High-Resolution Electron Microscopy

The precipitation and dissolution of water-soluble minerals in aqueous systems is a familiar process occurring commonly in nature. Understanding mineral nucleation and growth during its precipitation is highly desirable, but past <i>in situ</i> techniques have suffered from limited spatial and temporal resolution. Here, by using <i>in situ</i> graphene liquid cell electron microscopy, mineral nucleation and growth processes are demonstrated in high spatial and temporal resolution. We precipitate the mineral thenardite (Na₂SO₄) from aqueous solution with electron-beam-induced radiolysis of water. We demonstrate that minerals nucleate with a two-dimensional island structure on the graphene surfaces. We further reveal that mineral grains grow by grain boundary migration and grain rotation. Our findings provide a direct observation of the dynamics of crystal growth from ionic solutions

Direct Realization of Complete Conversion and Agglomeration Dynamics of SnO₂ Nanoparticles in Liquid Electrolyte

The conversion reaction is important in lithium-ion batteries because it governs the overall battery performance, such as initial Coulombic efficiency, capacity retention, and rate capability. Here, we have demonstrated in situ observation of the complete conversion reaction and agglomeration of nanoparticles (NPs) upon lithiation by using graphene liquid cell transmission electron microscopy. The observation reveals that the Sn NPs are nucleated from the surface of SnO₂, followed by merging with each other. We demonstrate that the agglomeration has a stepwise process, including rotation of a NP, formation of necks, and subsequent merging of individual NPs