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Lithium-ion batteries have dominated the field of electrochemical energy storage for years due to their high energy density. Recently, with the rapid development of E-mobility, the quest for high power and high energy batteries with reduced production costs has aroused great interest and is still a huge challenge. The energy density at battery level can be increased by using electrodes with thicknesses > 150 μm. However, capacity fade of thick-film electrodes at C-rates > C/2 is observed. To compensate the capacity loss, 3D architectures with a high aspect ratio are produced using ultrafast laser ablation. In addition, aqueous processing of cathodes using water-based binders can achieve environmentally friendly production and cost reduction by replacing the conventional organic PVDF binder and the toxic and volatile NMP solvent. However, the pH value of aqueous processed cathode slurries increases to 12 due to the reaction between active material and water, which decreases the specific capacity of the cells and on the other side results in chemical corrosion of the current collector during casting. In order to determine the optimal pH range and avoid the damage of the current collector, slurries with pH values ranging from 8 to 12 are manufactured. In this work, thick-film Li(Ni0.6Mn0.2Co0.2)O2 electrodes are manufactured with aqueous binders and acid adjustment, and are subsequently structured using ultrafast laser ablation. This combination is beneficial to achieve green production, low cost, high power, and high energy application of lithium-ion batteries.

The development of high areal energy density electrodes with layered metal oxide cathode materials is currently worldwide a main topic in research and industry. Water-based binders were applied in the presented work for the manufacturing of NMC 622 (Li(Ni0.6Mn0.2Co0.2)O2) cathodes in order to achieve environmental friendly and cost-reduced production, replacing the conventional organic PVDF binder and the toxic and volatile NMP solvent. However, the pH value of aqueous processed cathode slurries increases to over 12 due to the reaction between NMC 622 particles and water, which decreases the specific discharge capacity of the cells and on the other side results in the chemical corrosion of the current collector during casting. In order to avoid the damage of the current collector and protect the cathode material, different acids could be applied during mixing process to adjust the slurry pH value. In addition, the energy density at battery level can be increased with increasing electrode film thickness which corresponds to an enhanced areal capacity. However, capacity fading of thick-film electrodes at C-rates above C/2 is mainly due to a limited lithium-ion diffusion kinetics and crack formation in cathode particles. 3D electrode architectures produced by ultrafast laser ablation are proven to improve the capacity retention at high discharge rates and the electrolyte wettability of electrodes as reported in our previous works. In this work, NMC 622 electrodes with a film thickness of 150 µm (5.8 mAh/cm2) were manufactured with aqueous binders TRD 202A and CMC, and were subsequently laser structured. With increasing film thickness from 70 µm to 150 µm, the mass loading of cathodes increased from 17 mg/cm2 to 36 mg/cm2. The slurry pH values were adjusted between 9 - 10 with citric acid (CA), phosphoric acid (PA), and acetic acid (AC). The dried electrodes were characterized using XPS and SEM. The unstructured and structured electrodes with different thicknesses were afterwards assembled versus lithium in coin cells. Rate capability test and cyclic voltammetry (CV) were performed in order to investigate the electrochemical performance of the electrodes. Cells containing 70 µm cathodes with PA and CA+PA showed about 10 mAh/g higher capacity at C/20 to C/5 compared to cells with PA, while at 1C to 3C cells with CA showed the lowest capacities With increasing electrode film thickness, cells with PA and PA+CA retained 5-10 mAh/g more capacity than cells with CA at C/20 to C/5. The cells with PA maintained about 120 mAh/g discharge capacity at C/2, while cells with PA+CA and CA showed about 80 mAh/g and 45 mAh/g, respectively. In comparison to cells with unstructured electrodes, laser structuring increased the discharge capacity of cells with 70 µm electrodes from 1C to 3C, regardless of the type of added acid. As for cells with thick-film electrodes, the discharge capacity of cells containing structured electrodes with CA+PA increased to 120 mAh/g, which is about 40 mAh/g higher compared to cells with unstructured electrodes. Finally, CV proved that the addition of acids had no effect on the redox reaction of NMC 622.

Lithium-ion batteries have led the revolution in portable electronic devices and electrical vehicles due to their high gravimetric energy density. In particular, layered cathode material Li(Ni0.6Mn0.2Co0.2)O2 (NMC 622) can deliver high specific capacities of about 180 mAh/g. However, traditional cathode manufacturing involves high processing costs and environmental issues due to the use of organic binder polyvinylidenfluoride (PVDF) and highly toxic solvent N-methyl-pyrrolidone (NMP). In order to overcome these drawbacks, aqueous processing of thick-film NMC 622 cathodes was studied using carboxymethyl cellulose and fluorine acrylic hybrid latex as binders. Acetic acid was added during the mixing process to obtain slurries with pH values varying from 7.4 to 12.1. The electrode films could be produced with high homogeneity using slurries with pH values smaller than 10. Cyclic voltammetry measurements showed that the addition of acetic acid did not affect the redox reaction of active material during charging and discharging. Rate capability tests revealed that the specific capacities with higher slurry pH values were increased at C-rates above C/5. Cells with laser structured thick-film electrodes showed an increase in capacity by 40 mAh/g in comparison to cells with unstructured electrodes.

From the perspective of big data such as Baidu heat map and GIS kernel density analysis, this paper analyzed the gathering situation of residents of Dashiyuan at different times and the use of public service facilities, as well as problems existing in the old community of Dashiyuan in Nanchang City, and put forward targeted recommendations.

In recent years, bird damage has become one of the major hidden dangers of power grid security. How to reduce the harm of bird activities to power equipment and promote the harmonious coexistence of human and birds has become a new social topic for power grid enterprises to carry out transmission line operation and maintenance work. Due to the wide distribution area of transmission lines, it is a waste of human and material resources to drive away birds blindly, and it needs a long time to adhere, so it is difficult to effectively prevent bird damage. Therefore, the prediction of the probability of bird damage is a powerful tool which can effectively reduce bird damage. This paper provides an effective method to predict bird damage. Firstly, the effects of topography, surrounding environment, voltage class, tower type, wire arrangement and season on bird damage are analyzed respectively. Then, multiple linear regression is used to establish the model between the occurrence probability and characteristic factors of bird damage, and correlation coefficient is used to evaluate the accuracy of the model. Experimental results show that the proposed model has high accuracy and reliability.

The stability of aluminum (Al) nanoparticles is a key issue that determines the energy performance of solid fuels, Al-based green propellants, and fuel cells. The surface native oxide shell (Al2O3)...