Relocation of Cobalt Ions in Electrochemically Delithiated LiCoPO₄ Cathode Materials

Relocation of Cobalt Ions in Electrochemically Delithiated LiCoPO₄ Cathode Material

Total Synthesis and Evaluation of Vinblastine Analogues Containing Systematic Deep-Seated Modifications in the Vindoline Subunit Ring System: Core Redesign

The total synthesis of a systematic series of vinblastine analogues that contain deep-seated structural modifications to the core ring system of the lower vindoline subunit is described. Complementary to the vindoline 6,5 DE ring system, compounds with 5,5, 6,6, and the reversed 5,6 membered DE ring systems were prepared. Both the natural <i>cis</i> and unnatural <i>trans</i> 6,6-membered ring systems proved accessible, with the latter representing a surprisingly effective class for analogue design. Following Fe­(III)-promoted coupling with catharanthine and in situ oxidation to provide the corresponding vinblastine analogues, their evaluation provided unanticipated insights into how the structure of the vindoline subunit contributes to activity. Two potent analogues (<b>81</b> and <b>44</b>) possessing two different unprecedented modifications to the vindoline subunit core architecture were discovered that matched the potency of the comparison natural products and both lack the 6,7-double bond whose removal in vinblastine leads to a 100-fold drop in activity

Exfoliated MoS₂ and MoSe₂ Nanosheets by a Supercritical Fluid Process for a Hybrid Mg–Li-Ion Battery

The ultrathin two-dimensional nanosheets of layered transition-metal dichalcogenides (TMDs) have attracted great interest as an important class of materials for fundamental research and technological applications. Solution-phase processes are highly desirable to produce a large amount of TMD nanosheets for applications in energy conversion and energy storage such as catalysis, electronics, rechargeable batteries, and capacitors. Here, we report a rapid exfoliation by supercritical fluid processing for the production of MoS₂ and MoSe₂ nanosheets. Atomic-resolution high-angle annular dark-field imaging reveals high-quality exfoliated MoS₂ and MoSe₂ nanosheets with hexagonal structures, which retain their 2H stacking sequence. The obtained nanosheets were tested for their electrochemical performance in a hybrid Mg–Li-ion battery as a proof of functionality. The MoS₂ and MoSe₂ nanosheets exhibited the specific capacities of 81 and 55 mA h g^–1, respectively, at a current rate of 20 mA g^–1

Unravelling the Surface Structure of MgMn₂O₄ Cathode Materials for Rechargeable Magnesium-Ion Battery

The spinel MgMn₂O₄, a cathode material with theoretical capacity of 272 mA h g^–1, holds promise for future application in high volumetric magnesium-ion batteries. Atomic-resolution imaging of the structure of the spinel and its surface composition would advance our understanding on its electrochemical properties, mass, and charge transport behavior in electrodes. We observe directly, by aberration-corrected scanning transmission electron microscopy (STEM), the atomic structure of cubic spinel MgMn₂O₄ for the first time. More importantly, we find that a thin stable surface layer of rocksalt MgMnO₂ was grown on a bulk cubic spinel phase. The formation of a rocksalt phase was induced by reconstruction of the spinel phase, i.e., the insertion of Mg into the spinel lattice together with Mg/Mn cation exchange and Frenkel-defect-mediated relocation of Mg cations. This new structural analysis provides a critical step toward understanding and tuning the electrochemical performance of spinel oxide in rechargeable Mg-ion batteries

Unravelling the Surface Structure of MgMn₂O₄ Cathode Materials for Rechargeable Magnesium-Ion Battery

The spinel MgMn₂O₄, a cathode material with theoretical capacity of 272 mA h g^–1, holds promise for future application in high volumetric magnesium-ion batteries. Atomic-resolution imaging of the structure of the spinel and its surface composition would advance our understanding on its electrochemical properties, mass, and charge transport behavior in electrodes. We observe directly, by aberration-corrected scanning transmission electron microscopy (STEM), the atomic structure of cubic spinel MgMn₂O₄ for the first time. More importantly, we find that a thin stable surface layer of rocksalt MgMnO₂ was grown on a bulk cubic spinel phase. The formation of a rocksalt phase was induced by reconstruction of the spinel phase, i.e., the insertion of Mg into the spinel lattice together with Mg/Mn cation exchange and Frenkel-defect-mediated relocation of Mg cations. This new structural analysis provides a critical step toward understanding and tuning the electrochemical performance of spinel oxide in rechargeable Mg-ion batteries

Disulfide-Bridged (Mo₃S₁₁) Cluster Polymer: Molecular Dynamics and Application as Electrode Material for a Rechargeable Magnesium Battery

Exploring novel electrode materials is critical for the development of a next-generation rechargeable magnesium battery with high volumetric capacity. Here, we showed that a distinct amorphous molybdenum sulfide, being a coordination polymer of disulfide-bridged (Mo₃S₁₁) clusters, has great potential as a rechargeable magnesium battery cathode. This material provided good reversible capacity, attributed to its unique structure with high flexibility and capability of deformation upon Mg insertion. Free-terminal disulfide moiety may act as the active site for reversible insertion and extraction of magnesium

Disulfide-Bridged (Mo₃S₁₁) Cluster Polymer: Molecular Dynamics and Application as Electrode Material for a Rechargeable Magnesium Battery

Exploring novel electrode materials is critical for the development of a next-generation rechargeable magnesium battery with high volumetric capacity. Here, we showed that a distinct amorphous molybdenum sulfide, being a coordination polymer of disulfide-bridged (Mo₃S₁₁) clusters, has great potential as a rechargeable magnesium battery cathode. This material provided good reversible capacity, attributed to its unique structure with high flexibility and capability of deformation upon Mg insertion. Free-terminal disulfide moiety may act as the active site for reversible insertion and extraction of magnesium