New Insight into Bulk Structural Degradation of High-Voltage LiCoO2 at 4.55 V.

The aggravated mechanical and structural degradation of layered oxide cathode materials upon high-voltage charging invariably causes fast capacity fading, but the underlying degradation mechanisms remain elusive. Here we report a new type of mechanical degradation through the formation of a kink band in a Mg and Ti co-doped LiCoO2 cathode charged to 4.55 V (vs Li/Li+). The local stress accommodated by the kink band can impede crack propagation, improving the structural integrity in a highly delithiated state. Additionally, machine-learning-aided atomic-resolution imaging reveals that the formation of kink bands is often accompanied by the transformation from the O3 to O1 phase, which is energetically favorable as demonstrated by first-principles calculations. Our results provide new insights into the mechanical degradation mechanism of high-voltage LiCoO2 and the coupling between electrochemically triggered mechanical failures and structural transition, which may provide valuable guidance for enhancing the electrochemical performance of high-voltage layered oxide cathode materials for lithium-ion batteries.

Van der Waals phase transition investigation toward high-voltage layered cathodes.

High-voltage phase transition constitutes the major barrier to accessing high energy density in layered cathodes. However, questions remain regarding the origin of phase transition, because the interlayer weak bonding features cannot get an accurate description by experiments. Here, we determined van der Waals (vdW) interaction (vdWi) in LixCoO2 via visualizing its electron density, elucidating the origin of O3─O1 phase transition. The charge around oxygen is distorted by the increasing Co─O covalency. The charge distortion causes the difference of vdW gap between O3 and O1 phases, verified by a gap corrected vdW equation. In a high charging state, excessive covalency breaks the vdW gap balance, driving the O3 phase toward a stable O1 one. This interpretation of vdWi-dominated phase transition can be applied to other layered materials, as shown by a map regarding degree of covalence. Last, we introduce the cationic potential to provide a solution for designing high-voltage layered cathodes.

An orbital strategy for regulating the Jahn-Teller effect.

The Jahn-Teller effect (JTE) arising from lattice-electron coupling is a fascinating phenomenon that profoundly affects important physical properties in a number of transition-metal compounds. Controlling JT distortions and their corresponding electronic structures is highly desirable to tailor the functionalities of materials. Here, we propose a local coordinate strategy to regulate the JTE through quantifying occupancy in the [Formula: see text] and [Formula: see text] orbitals of Mn and scrutinizing the symmetries of the ligand oxygen atoms in MnO6 octahedra in LiMn2O4 and Li0.5Mn2O4. The effectiveness of such a strategy has been demonstrated by constructing P2-type NaLi x Mn1 - x O2 oxides with different Li/Mn ordering schemes. In addition, this strategy is also tenable for most 3d transition-metal compounds in spinel and perovskite frameworks, indicating the universality of local coordinate strategy and the tunability of the lattice-orbital coupling in transition-metal oxides. This work demonstrates a useful strategy to regulate JT distortion and provides useful guidelines for future design of functional materials with specific physical properties.

Efficacy Analysis of Physical Therapy in Treating Chronic Prostatitis: Unblocking Obstructed Glandular Ducts Could Be a Novel Treatment Strategy.

Objective: This study investigates the efficacy of physical therapy in treating chronic prostatitis grounded on the glandular duct blockage theory. Methods: The study includes patients who were diagnosed and treated for chronic prostatitis between November 2022 and July 2023 at Renhui clinic in Jiangmen, Guangdong and Renhui frontline clinic in Shenzhen Guangdong. The recorded data includes the frequency of physical therapies including prostate massages, rectal probe high-frequency vibration treatment, and low-intensity extracorporeal shockwave therapy (Li-ESWT). Post-treatment urine sediment was collected for microscopic examination, and the scores of each patient on the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and the Premature Ejaculation Diagnostic Tool (PEDT) were recorded pre- and post-treatment in order to calculate the effectiveness rate. Results: The study involved a total of 48 patients, of which 26 were diagnosed with premature ejaculation. On average, each patient received 2.1 prostate massages, underwent 4.1 rectal probe high-frequency vibration treatments, and 8.3 Li-ESWT sessions. Following treatment, the initial microscopic examination of the urine sediment revealed aged white blood cell clusters, prostate calculi clusters, and inactive sperm clusters, all appearing in the shape of glandular tubes. The mean NIH-CPSI scores pre- and post-treatment were 27.2±6.9 and 18.0±6.6, respectively, indicating an effectiveness rate of 81.3%. The average PEDT scores pre- and post-treatment were 14.5±3.5 and 10.5±4.2, respectively, with an effectiveness rate of 53.8%. Conclusion: Unblocking obstructed glandular ducts might provide a novel therapeutic strategy for treating chronic prostatitis.