In this article, we report a study of the electrochemical performance and degradation mechanism of tin (Sn) nanoparticle anodes in potassium-ion batteries (KIBs). A high capacity of 197 mAh/g was found for the Sn nanoparticles in KIBs. In situ transmission electron microscopy characterization revealed a two-step potassiation mechanism: formation of a KSn phase after full potassiation and reversible nanopore formation during the cycling of Sn nanoparticles. However, significant capacity fading occurred after a few cycles, which was caused by the severe pulverization of the Sn nanoparticles. This work offers a fundamental understanding of the reaction and degradation mechanisms of alloying-type anodes for KIBs, shedding light on the development of high-performance KIBs.

The formation mechanism of the all-inorganic halide perovskite (AIHP)-related (e.g., CsPbBr3, Cs4PbBr6, and CsPb2Br5) nanocrystals have been studied, which is helpful to realize rational design of AIHP-related nanocrystals.

Free-standing nitrogen-doped cup-stacked carbon nanotube (NCSCNT) mats were synthesized and tested as anodes for potassium-ion batteries (KIBs). The edge-open structure character of the NCSCNTs allows a facile insertion of K + ions into the carbon nanotubes. Combined with the nanosized feature and interconnected flexible structure, the NCSCNTs demonstrate impressive electrochemical performance with a reversible capacity of 323 mA h/g and a markedly improved rate capability retaining 75 mA h/g even at 1000 mA/ g. Additionally, the free-standing NCSCNT mat electrodes eliminate the utilization of nonactive components of binders and conductive agents during the battery assembly and thereby significantly enhance the total specific capacity of the electrodes.

Nanoscale materials modified by crystal defects exhibit significantly different behaviours upon chemical reactions such as oxidation, catalysis, lithiation and epitaxial growth. However, unveiling the exact defect-controlled reaction dynamics (e.g. oxidation) at atomic scale remains a challenge for applications. Here, using in situ high-resolution transmission electron microscopy and first-principles calculations, we reveal the dynamics of a general site-selective oxidation behaviour in nanotwinned silver and palladium driven by individual stacking-faults and twin boundaries. The coherent planar defects crossing the surface exhibit the highest oxygen binding energies, leading to preferential nucleation of oxides at these intersections. Planar-fault mediated diffusion of oxygen atoms is shown to catalyse subsequent layer-by-layer inward oxide growth via atomic steps migrating on the oxide-metal interface. These findings provide an atomistic visualization of the complex reaction dynamics controlled by planar defects in metallic nanostructures, which could enable the modification of physiochemical performances in nanomaterials through defect engineering.

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