Enhancing the Structural Stability and Electrochemical Performance of High-Nickel Cathode Materials through Ti Doping with an Exothermic Non-oxide Precursor.

The foreseeable global cobalt (Co) crisis has driven the demand for cathode materials with less Co dependence, where high-nickel layered oxides are a promising solution due to their high energy density and low cost. However, these materials suffer from poor cycling stability and rapid voltage decay due to lattice displacement and nanostrain accumulation. Here, we introduced an exothermic TiN dopant via a scalable coating method to stabilize LiNi0.917Co0.056Mn0.026O2 (NCM92) materials. The exothermic reaction of TiN conversion generates extra heat during the calcination process on the cathode surface, promotes the lithiation process, and tunes the morphology of the cathode material, resulting in compact and conformal smaller particle sizes to provide better particle integration and lithium diffusion coefficient. Moreover, the Ti dopant substitutes the Ni3+ site to generate stronger Ti-O bonding, leading to higher structural stability and extended cycle life. The Ti-doped NCM (NCM92_TiN) shows a remarkable cycling stability of maintaining 80% capacity retention for 400 cycles, while bare NCM92 can only reach 88 cycles. Furthermore, the NCM92_TiN cathodes demonstrate an enhanced rate capability and achieve a discharge capacity of over 168 mAh g-1 at 5C.

Interfacial solvation-structure regulation for stable Li metal anode by a desolvation coating technique.

Rechargeable lithium (Li) metal batteries face challenges in achieving stable cycling due to the instability of the solid electrolyte interphase (SEI). The Li-ion solvation structure and its desolvation process are crucial for the formation of a stable SEI on Li metal anodes and improving Li plating/stripping kinetics. This research introduces an interfacial desolvation coating technique to actively modulate the Li-ion solvation structure at the Li metal interface and regulate the participation of the electrolyte solvent in SEI formation. Through experimental investigations conducted using a carbonate electrolyte with limited compatibility to Li metal, the optimized desolvation coating layer, composed of 12-crown-4 ether-modified silica materials, selectively displaces strongly coordinating solvents while simultaneously enriching weakly coordinating fluorinated solvents at the Li metal/electrolyte interface. This selective desolvation and enrichment effect reduce solvent participation to SEI and thus facilitate the formation of a LiF-dominant SEI with greatly reduced organic species on the Li metal surface, as conclusively verified through various characterization techniques including XPS, quantitative NMR, operando NMR, cryo-TEM, EELS, and EDS. The interfacial desolvation coating technique enables excellent rate cycling stability (i.e., 1C) of the Li metal anode and prolonged cycling life of the Li||LiCoO2 pouch cell in the conventional carbonate electrolyte (E/C 2.6 g/Ah), with 80% capacity retention after 333 cycles.

Promoting a Stable Interface Using Localized High-Concentration Carbonate-Based Electrolyte for Li Metal Batteries.

Rechargeable lithium metal batteries (LMBs) using high-voltage cathodes have been attractive in delivering high-energy density, but it is still challenging to reach excellent cycling performance for practical applications due to the notorious reactivity of metallic lithium as well as the unstable nature of the cathode. Here, we demonstrate a formulated carbonated-based electrolyte with LiPF6 that supports the most commercial aggressive and high-voltage cathode with the combination of cosolvent, diluent, and additives to address the issue in LMBs by providing a stable interface/interphase on both the anode and cathode. The electrolyte's solvation structure is adjusted to reduce free carbonate solvents in the decomposition and contribution to the solid-electrolyte interphase (SEI) formation. The thin LiF-rich SEI and achieved uniform Li deposition afforded a high Coulombic efficiency of 99.5% for Li|Cu half cells and good cycling stability in Li||NMC811 full cells. The Li||NMC811 full cells showed good cycling life with a capacity retention of ∼80% over 280 cycles at an areal capacity of 4.0 mAh cm-2, the lean electrolyte of 5 µL mAh-1, and a thin 50 µm Li metal, demonstrating its advantage toward practical applications.

Individual and Occupational Differences in Perceived Organisational Culture of a Central Hospital in Vietnam.

Many hospitals in developing countries, including Vietnam, are facing the challenges of increasingly noncommunicable diseases and the financial autonomy policy from the government. To adapt to this new context requires understanding and changing the current organisational culture of the hospitals. However, little has been known about this in resource-constrained healthcare settings. The objectives of this study were to examine the four characteristics of the organisational culture and test selected individual and occupational differences in the organisational culture of a Vietnam central hospital. In a cross-sectional study using the Organisation Culture Assessment Instrument (OCAI) with the Competing Value Framework (CVF), including 4 factors, Clan, Adhocracy, Hierarchy, and Market, health workers currently working at Quang Nam General Hospital were interviewed. The results indicated the current cultural model was more internally focused with two dominant cultures, Clan and Hierarchy, while, for the desired model, the Clan culture was the most expected one. Comparing between the current and desired pattern, the down trend was found for all types of culture, except the Clan culture, and there were significant differences by domains of organisational culture. Furthermore, the current and desired models were differently distributed by key individual characteristics. These differences have raised a number of interesting directions for future research. They also suggest that, to build a hospital organisational culture to suit both current and future contexts as per employees' assessment and expectation, it is important to take individual and institutional variations into account.