Ce-modified LiNi0.5Co0.2Mn0.3O2 cathode with enhanced surface and structural stability for Li ion batteries

Machine learning-assisted precision inverse design research of ternary cathode materials: A new paradigm for material design

The Li+ diffusion rate directly affects the cathode rate performance, and it is inefficient to precision design cathode materials with excellent rate performance using the Edison approach method. Here, a new paradigm for the precision design of ternary cathode materials is exploited. The data of Ni-Co-Mn ternary (NCM) cathode materials doped with Li sites and transition metal (TM) sites, respectively, were extracted from publications, and the model Gradient Boosted Regression (GBR), which can accurately reveal the relationship between physical characterization variables and Li+ diffusion rate, was trained. Subsequently, the inverse design of the synthetic experimental parameters was carried out based on the desired target Li+ diffusion rate with the GBR model and particle swarm optimization (PSO) algorithm. A global search of the crystal structure is then performed using the Universal Structure Predictor: Evolutionary Xtallography (USPEX) code based on the parameters of the reverse design. Finally, first-principle calculations are performed to verify Li+ diffusion rate of the searched structures. The theoretical calculations show that the Li+ diffusion rates of the designed materials Ce-NCM and Li/Ni@Ce-NCM are 8.66 × 10-9 cm2/s, and 9.67 × 10-9 cm2/s, respectively, which are better than the target values (1.23 × 10-10 cm2/s). The density functional theory (DFT) calculations of charge transfer density indicate that moderate Li/Ni mixing induces a built-in electric field, which facilitates Li+ diffusion in the NCM cathode materials. This work demonstrates the potential of accurate inverse design of ternary cathode materials, advances the research process of ternary cathode materials, and provides a reference for the design of cathode materials and its counterparts. This work will open new avenues for designing cathode materials and counterparts, potentially revolutionizing traditional trial-and-error experiments.

Ag-CeO2 Based on Electrochemical Sensor for High-Efficient On-Site Detection of Nitrite in Aquaculture Water and Beverages

Nitrite is one of the most common nitrogenous compounds, which is not only an important indicator of aquaculture water but also widely used as a food additive. Its potential toxicity poses a huge threat to aquatic products and human health. Therefore, it is important to develop a convenient and rapid sensor for the high-efficient onsite detection of nitrite. In this work, a novel electrochemical sensor was developed for the qualitative and quantitative analysis of nitrite. The developed nitrite electrochemical detection system is easily applied in onsite detection. The electrochemical working electrode was constructed based on the combination of Ag-CeO2 and conductive carbon paste (CPE) with excellent electrocatalysis activity and rapid electron transfer ability. By the application of the developed system and under the optimal conditions, the linear range was from 40.0 μM to 500.0 μM, and the detection limit was reduced to 4.3 μM. The recovery was between 92.1% and 108.1%, and the relative standard deviations (RSDs) were 0.49%~9.31%. The sensor exhibited superior reproducibility, high stability sensitivity, and anti-interference ability, confirming its effectiveness for nitrite analysis. Finally, the developed electrochemical sensor was successfully applied to detect nitrite in beverages and aquaculture water samples, indicating that this approach has great potential in onsite food testing and environmental monitoring.

Ti-substituted O3-type layered oxide cathode material with high-voltage stability for sodium-ion batteries

O3-type layered transition metal oxides (Na_xTMO₂) have attracted extensive attention as a promising cathode material for sodium-ion batteries because of their high capacity. However, the irreversible phase transition especially cycled under high voltage remains a concerning challenge for Na_xTMO₂. Herein, a Ti-substituted NaNi_0.5Co_0.2Mn_0.3O₂ cathode with strongly suppressed phase transition and enhanced storage stability is investigated. The Ti substitution effectively inhibits the irreversible phase transition and alleviates the structural change even charged to 4.3 V during the repeated Na⁺ deintercalation process. After storing in air or water, the original O3 phase structure of the material is integrally maintained without the generation of impurity phase. As a result, the as-prepared material shows excellent long-term cycle stability and rate performance when charged to a high voltage of 4.3 V.