Scalable Precise Nanofilm Coating and Gradient Al Doping Enable Stable Battery Cycling of LiCoO2 at 4.7†V.

The quest for smart electronics with higher energy densities has intensified the development of high-voltage LiCoO2 (LCO). Despite their potential, LCO materials operating at 4.7 V faces critical challenges, including interface degradation and structural collapse. Herein, we propose a collective surface architecture through precise nanofilm coating and doping that combines an ultra-thin LiAlO2 coating layer and gradient doping of Al. This architecture not only mitigates side reactions, but also improves the Li+ migration kinetics on the LCO surface. Meanwhile, gradient doping of Al inhibited the severe lattice distortion caused by the irreversible phase transition of O3-H1-3-O1, thereby enhanced the electrochemical stability of LCO during 4.7 V cycling. DFT calculations further revealed that our approach significantly boosts the electronic conductivity. As a result, the modified LCO exhibited an outstanding reversible capacity of 230 mAh g-1 at 4.7 V, which is approximately 28 % higher than the conventional capacity at 4.5 V. To demonstrate their practical application, our cathode structure shows improved stability in full pouch cell configuration under high operating voltage. LCO exhibited an excellent cycling stability, retaining 82.33 % after 1000 cycles at 4.5 V. This multifunctional surface modification strategy offers a viable pathway for the practical application of LCO materials, setting a new standard for the development of high-energy-density and long-lasting electrode materials.

A facile and efficient strategy for the fabrication of porous linseed gum/cellulose superabsorbent hydrogels for water conservation.

The linseed gum/cellulose composite hydrogels were successfully fabricated by mixing cellulose and linseed gum solutions dissolved in the NaOH/urea aqueous system and cross-linked with epichlorohydrin. The morphology and structure of the composite hydrogels were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). The swelling ratio and water retention properties were investigated. The results revealed that linseed gum mainly contributed to water adsorption, whereas the cellulose acted as a backbone to strengthen the porous structure. This work provided a simple way to prepare cellulose-based superabsorbent hydrogels, which could be potentially applied as an effective water conservation material in agriculture.

Production of novel "functional oil" rich in diglycerides and phytosterol esters with "one-pot" enzymatic transesterification.

Diglycerides and phytosterol esters are two important functional lipids. Phytosterol esters mixed with dietary diglyceride could not only influence body weight but also prevent or reverse insulin resistance and hyperlipidemia. In this study, a kind of novel "functional oil" rich in both diglycerides and phytosterol esters was prepared with "one-pot" enzymatic transesterification. First, lipase AYS (Candida rugosa) was immobilized on the porous cross-linked polystyrene resin beads (NKA) via hydrophobic interaction. The resulting immobilized AYS showed much better transesterification activity and thermal stability to freeways. On the basis of the excellent biocatalyst prepared, a method for high-efficiency enzymatic esterification of phytosterols with different triglycerides to produce corresponding functional oils rich in both diglycerides and phytosterol esters was developed. Four functional oils rich in both diglycerides and phytosterol esters with conversions >92.1% and controllable fatty acid composition were obtained under the optimized conditions: 80 mmol/L phytosterols, 160 mmol/L triglycerides, and 25 mg/mL AYS@NKA at 180 rpm and 50 °C for 12 h in hexane. The prepared functional oil possessed low acid value (≤1.0 mgKOH/g), peroxide value (≤2.1 mmol/kg), and conjugated diene value (≤1.96 mmol/kg) and high diglyceride and phytosterol ester contents (≥10.4 and ≥20.2%, respectively). All of the characteristics favored the wide application of the functional oil in different fields of functional food.

Lipase immobilization on hyper-cross-linked polymer-coated silica for biocatalytic synthesis of phytosterol esters with controllable fatty acid composition.

In this study, a novel mixed-mode composite material, SiO(2)@P(MAA-co-VBC-co-DVB), was prepared via the hyper-cross-linking of its precursor, which was produced via suspension polymerization in the presence of SiO(2) particles. Candida rugosa lipase (CRL) was immobilized on the SiO(2)@P(MAA-co-VBC-co-DVB) particles via hydrophobic and weak cation-exchange interaction. The resulting immobilized CRL showed much better thermal stability and reusability in comparison to free CRL. On the basis of the excellent biocatalyst prepared, a method for high-efficiency enzymatic esterification of phytosterols with different fatty acids to produce the corresponding phytosterol esters was developed. Six phytosterol esters with conversions above 92.1% and controllable fatty acid composition were obtained under the optimized conditions: 80 µmol/mL phytosterols, 160 µmol/mL linolenic acid, and 15 mg/mL CRL@HPCS at 300 rpm and 50 °C for 7 h in 30 mL of isooctane. The prepared phytosterol esters possessed a low acid value (≤0.86 mg of KOH/g), peroxide value (≤3.3 mequiv/kg), and conjugated diene value (≤1.74 mmol/kg) and high purity (≥97.8%) and fatty solubility (≥28.9 g/100 mL). All the characteristics favored the wide application of phytosterol esters with controllable fatty acid composition in different fields of functional food.

Ultrasonic pretreatment for lipase-catalyed synthesis of phytosterol esters with different acyl donors.

This study is focused on the enzymatic esterification of phytosterols with different acyl donors to produce the corresponding phytosterol esters catalyzed by Canadia sp. 99-125 lipase under ultrasound irradiation. An ultrasonic frequency of 35 kHz, power of 200 W and time of 1h was determined to guarantee satisfactory degree of esterification and lipase activity. The influence of temperature, substrates concentration and molar ratio was investigated subsequently. The optimum production was achieved in isooctane system at 60°C with phytosterol concentration of 150 µmol/mL and phytosterol to fatty acid molar ratio of 1:1.5, resulting in a phytosterol esters conversion of above 85.7% in short reaction time (8h). Phytosterols esters could also be converted in high yields to the corresponding long-chain acyl esters via transesterification with triacylglycerols (above 90.3%) under ultrasound irradiation. In optimum conditions, the overall esterification reaction rate using the ultrasonic pretreatment process was above 2-fold than that of mechanical stirring process without damage the lipase activity.

Immobilization of Candida rugosa lipase on hydrophobic/strong cation-exchange functional silica particles for biocatalytic synthesis of phytosterol esters.

In this work, mixed-mode silica particles functionalized with octyl and sulfonic acid groups was conveniently prepared by co-bonding a mixture of n-octyltriethoxysilane and 3-mercaptopropyltriethoxysilane and then oxidized with hydrogen peroxide. Candida rugosa lipase (CRL) was immobilized on the mixed-mode silica particles via hydrophobic and strong cation-exchange interaction. The resulting immobilized CRL increased remarkably its stability at high temperature in comparison to free CRL. The immobilized CRL was used as biocatalysts for enzymatic esterification of phytosterols with free fatty acids (FFAs) to produce phytosterol esters. The phytosterols linolenate esterification degree of 95.3% was obtained under the optimized condition. Phytosterols esters could also been converted in high yields to the corresponding long-chain acyl esters via transesterification with methyl esters of fatty acids (80.5%) or triacylglycerols (above 95.5%) using mixed-mode silica particles immobilized CRL as biocatalyst. Furthermore, the immobilized CRL by absorption retained 78.6% of their initial activity after 7 recycles.