When fabricating Li‐rich layered oxide cathode materials, anionic redox chemistry plays a critical role in achieving a large specific capacity. Unfortunately, the release of lattice oxygen at the surface impedes the reversibility of the anionic redox reaction, which induces a large irreversible capacity loss, inferior thermal stability, and voltage decay. Therefore, methods for improving the anionic redox constitute a major challenge for the application of high‐energy‐density Li‐rich Mn‐based cathode materials. Herein, to enhance the oxygen redox activity and reversibility in Co‐free Li‐rich Mn‐based Li1.2Mn0.6Ni0.2O2 cathode materials by using an integrated strategy of Li2SnO3 coating‐induced Sn doping and spinel phase formation during synchronous lithiation is proposed. As an Li+ conductor, a Li2SnO3 nanocoating layer protects the lattice oxygen from exposure at the surface, thereby avoiding irreversible oxidation. The synergy of the formed spinel phase and Sn dopant not only improves the anionic redox activity, reversibility, and Li+ migration rate but also decreases Li/Ni mixing. The 1% Li2SnO3‐coated Li1.2Mn0.6Ni0.2O2 delivers a capacity of more than 300 mAh g−1 with 92% Coulombic efficiency. Moreover, improved thermal stability and voltage retention are also observed. This synergic strategy may provide insights for understanding and designing new high‐performance materials with enhanced reversible anionic redox and stabilized surface lattice oxygen.

With the increasing applications of metal-based nanoparticles in various commercial products, it is necessary to address their environmental fate and potential toxicity. In this work, we assessed the phytotoxicity of lanthanum oxide (La₂O₃) NPs to cucumber plants and determined its distribution and biotransformation in roots by TEM and EDS, as well as STXM and NEXAFS. LaCl₃ was also studied as a reference toxicant. La₂O₃ NPs and LaCl₃ were both transformed to needle-like LaPO₄ nanoclusters in the intercellular regions of the cucumber roots. In vitro experiments demonstrated that the dissolution of La₂O₃ NPs was significantly enhanced by acetic acid. Accordingly, we proposed that the dissolution of NPs at the root surface induced by the organic acids extruded from root cells played an important role in the phytotoxicity of La₂O₃ NPs. The reactions of active NPs at the nano-bio interface should be taken into account when studying the toxicity of dissolvable metal-based nanoparticles.

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The effect of oxygen vacancy and spinel phase integration on anionic and cationic redox in Li-rich cathode materials was unraveled.

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The migration of gold atoms attached to single vacancies near the edges of graphene ribbons is studied using density-functional theory calculations. The stable position for a single gold atom is found to be on top of a vacancy, as in an infinite graphene sheet. An energy of 5 eV is needed for the Au atom to move through the vacancy to the other side of the sheet, but the Au atom can migrate in lateral direction together with the vacancy, with a migration barrier of about 2.2 eV. The sites near the edges of the graphene layer are energetically more favorable for gold-atom-vacancy pairs than sites in the middle of extended graphene layers. The migration barriers for different pathways show that it is easier for the gold atom to move toward the edge where it can be captured. When the gold atom reaches the edge, it can migrate along the edge with an energy barrier of only 1.4 eV. Our results explain recent experimental observations ͓Y. Gan et al., Small 4, 587 ͑2008͔͒ and provide information on the dynamics of metal atoms on substitutional sites in graphene as well as on their agglomeration at defects and at edges of graphene ribbons.

The thermal conductivity of single-walled carbon nanotubes (SWCNTs) under axial stress is studied by nonequilibrium molecular dynamics simulation. The thermal conductivity is found to increase and then decrease with the tube elongation changing from an axially compressed state to a stretched state. The phonon density of states of the systems is analyzed to elucidate the variation of heat conduction with respect to the stress in CNTs. The primary peak of the phonon spectrum shows a blue shift or red shift as the SWCNT is compressed or stretched. These shifts correspond to the change of the elasticity coefficient of the CNTs. The variation trend of primary peak height of radial phonon spectra with axial strain is similar to that of the thermal conductivity, which indicates that the radial phonon modes, especially the high-frequency modes, play a dominant role in the heat conduction mechanism of CNTs.

In article number https://doi.org/10.1002/adfm.201806706, Xiangfeng Liu and co‐workers propose to tune the oxygen redox activity and reversibility in an Li‐rich Li1.2Mn0.6Ni0.2O2 cathode by an integrated strategy involving Li2SnO3 coating, Sn doping, and spinel phase combination. This synergy not only suppresses the lattice oxygen loss and improves the anionic redox activity and reversibility but also facilitates Li+ migration, which enhances electrochemical performance.