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Abstract Layered oxide cathode with a Li‐O‐vacancy configuration offers high capacity by leveraging additional oxygen redox reactions. However, it faces severe challenges of sluggish kinetics of oxygen redox reactions and lattice oxygen loss, resulting in slow Li⁺diffusion and rapid electrochemical degradation. Herein, Ti is introduced as electrochemical inactive element into Li‐O‐vacancy configuration to form Mn/vacancy/Ti arrangement within transition metal layers of layered oxide, achieving a marked increase in average output voltage at high current density compared with Ti‐free counterpart. Not only voltage hysteresis between charge and discharge processes can be significantly reduced, but rate capability can be heightened in Li_4/7[□_1/7Ti_1/7Mn_5/7]O₂by means of retrained over‐potential and improved Li⁺diffusivity. Furthermore, theoretical calculations suggest that these improvements stem from Ti substitution, which elongates the Li─O bond and lowers the Li⁺migration energy barrier. Besides, in situ differential electrochemical mass spectrometry and soft X‐ray absorption spectroscopy reveal the modified Li‐O‐vacancy configuration enables reversible anionic and cationic redox behaviors during cycling. These findings provide a promising strategy for tailoring oxygen redox activity and accelerating Li⁺diffusion kinetics in layered cathode materials with oxygen redox chemistry. 

Abstract Lithium‐rich transition metal chalcogenides are witnessing a revival as candidates for Li‐ion cathode materials, spurred by the boost in their capacities from transcending conventional redox processes based on cationic states and tapping into additional chalcogenide states. A particularly striking case is Li₂TiS_3‐ySe_y, which features a d⁰metal. While the end members are expectedly inactive, substantial capacities are measured when both Se and S are present. Using X‐ray absorption spectroscopy, it is shown that the electronic structure of Li₂TiS_3‐ySe_yis not a simple combination of the end members. The data confirm previous hypotheses that, in Li₂TiS_2.4Se_0.6, this behavior is underpinned by concurrent and reversible redox of only S and Se, and identify key electronic states. Moreover, wavelet transforms of the extended X‐ray absorption fine structure provide direct evidence of the formation of short Se–Se units upon charging. The study uncovers the underpinnings of this intriguing reactivity and highlights the richness of redox chemistry in complex solids. 

Abstract Li‐rich disordered rocksalt (DRS) oxyfluorides have emerged as promising high‐energy cathode materials for lithium‐ion batteries. While a high level of fluorination in DRS materials offers performance advantages, it can only be achieved via mechanochemical synthesis, which poses challenges of reproducibility and scalability. The definition of relationships between fluorination and structural stability is required to devise alternative methods that overcome these challenges. In this study, the thermal evolution of three highly fluorinated phases, Li₂TMO₂F (TM = Mn, Co, and Ni), is investigated in an inert atmosphere. Diffraction and spectroscopic techniques are utilized to examine their electronic and chemical states up until conditions of decomposition. The analysis reveals that the materials phase‐separate above 400 °C, at most. It is also observed that heat‐treated DRS materials exhibit intricate changes in the local coordination of the metals, including their spin, and ordering compared to the pristine states. The changes upon annealing are accompanied by a modulation of the voltage profile, including reduced hysteresis, when used as electrodes. These results provide an in‐depth understanding of the fundamental crystal chemistry of DRS oxyfluorides in view of their promising role as the next generation of Li‐ion cathodes. 

Abstract Li‐rich layered chalcogenides have recently led to better understanding of the anionic redox process and its associated high capacity while providing ways to overcome its practical limitations of voltage fade and irreversibility. This study reports on the feasibility of triggering anionic activity in Li₂TiS₃, through anionic substitution (Se for S) or cationic substitution (Fe for Ti). Herein, the chalcogenide chemical space is further explored to prepare mono‐substituted Li_1.7Ti_0.85Mn_0.45Ch₃(Ch = S/Se) and doubly substituted cationic and anionic phases (Li_1.7Ti_0.85Fe_0.45S_3‐zSe_z) which crystallize either in the O3‐ or O1‐type structures depending upon substituents. All series show a bell‐shape capacity variation as function of the transition metal (TM) substitution degree with values up to 240 mAh g⁻¹. For specific compositions, a structural O3 to O1 phase transition is observed upon Li removal, which is not reversible upon Li re‐insertion due to kinetic limitations and negatively affects long‐term cycling performance. Density functional theory (DFT) calculations confirm the O3/O1 relative stability along the different series and point subtle electronic differences in the TM‐doping, rationalizing the structural and electrochemical behaviors of these phases upon cycling. These findings provide further insights into the link between structural and electronic stability, which is of key importance for designing chalcogenide‐based anionic redox compounds. 

We present the successful synthesis and characterization of a one-dimensional high-entropy oxide (1D-HEO) exhibiting nanoribbon morphology. These 1D-HEO nanoribbons exhibit high structural stability at elevated temperatures (to 1000°C), elevated pressures (to 12 gigapascals), and long exposure to harsh acid or base chemical environments. Moreover, they exhibit notable mechanical properties, with an excellent modulus of resilience reaching 40 megajoules per cubic meter. High-pressure experiments reveal an intriguing transformation of the 1D-HEO nanoribbons from orthorhombic to cubic structures at 15 gigapascals followed by the formation of fully amorphous HEOs above 30 gigapascals, which are recoverable to ambient conditions. These transformations introduce additional entropy (structural disorder) besides configurational entropy. This finding offers a way to create low-dimensional, resilient, and high-entropy materials.