LiFePO_(4) as a dual-functional coating for separators in lithium-ion batteries:A new strategy for improving capacity and safety

Lithium-ion batteries(LIBs)require separators with high performance and safety to meet the increasing demands for energy storage applications.Coating electrochemically inert ceramic materials on conventional polyolefin separators can enhance stability but comes at the cost of increased weight and decreased capacity of the battery.Herein,a novel separator coated with lithium iron phosphate(LFP),an active cathode material,is developed via a simple and scalable process.The LFP-coated separator exhibits superior thermal stability,mechanical strength,electrolyte wettability,and ionic conductivity than the conventional polyethylene(PE)separator.Moreover,the LFP coating can actively participate in the electrochemical reaction during the charge-discharge process,thus enhancing the capacity of the battery.The results show that the LFP-coated separator can increase the cell capacity by 26%,and improve the rate capability by 29%at 4 C compared with the conventional PE separator.The LFP-coated separator exhibits only 1.1%thermal shrinkage at 140°C,a temperature even above the melting point of PE.This work introduces a new strategy for designing separators with dual functions for the next-generation LIBs with improved performance and safety.

Cu-Promoted Cobalt Oxide Film Catalyst for Efficient Gas Emissions Abatement

Thin film catalysts have been recently reported as promising catalysts owing to their good catalytic activity and reduced material amount, leading to low-cost efficient catalysts for gaseous emissions control. Here, we report the slight loading of Cu in cobalt spinel using a one-step pulsed-spray evaporation chemical vapor deposition(PSE-CVD) synthesis technique for efficient short-chain volatile organic compounds(VOCs) emissions treatment. Crystalline structure and morphology analyses revealed nano-crystallite sizes and open-like morphology. The catalytic performance was evaluated through the complete oxidation of C_3H_6, as a short-chain representative model of VOCs, at a high gas hourly space velocity(GHSV). Very good activity was obtained towards the complete abatement of C_3H_6 at low temperature and no carbon monoxide(CO) was formed during the oxidation process. Slightly-promoted Co_3O_4 catalyst with Cu introduction resulted in high catalytic activity comparing to the performance of the catalysts in the literature, due to the high dispersion of Cu and high active surface oxygen amount. Moreover, to evaluate the capability of the used catalysts under near realistic reaction conditions, CO_2 effect on the catalytic activity was performed and the catalyst exhibited very good results. Thus, the adopted slightly-doping strategy to tailor a high active catalyst at low temperature could establish a very promising route to strongly enhance the activity of such other catalysts towards gas emissions abatement at low temperature.

In-process failure analysis of thin-wall structures made by laser powder bed fusion additive manufacturing

Fabrication of thin-wall components using the laser powder bed fusion(LPBF)additive manufacturing(AM)technology was investigated for two“hard-to-weld”high gamma prime Ni-based superalloys RENé65(R65)and RENé108(R108).Simple block parts with wall thicknesses of 0.25 mm,1.00 mm,and5.00 mm are printed using a bidirectional laser scanning strategy without layer-wise rotation.Parts with walls thinner than 5 mm fail before reaching the designated build height.Results indicate that reduction of limiting build height(LBH)corresponds to the reduction of part thickness and is unaffected by alloy composition.On the contrary,the number of internal micro-cracks along columnar grain boundaries in the build direction(BD)increases with part thickness and is significantly higher in R108 than R65.These findings suggest that reduced LBH in parts with thinner walls is not caused by internal micro-crack formation.Fractography and finite element analysis(FEA)of the in-process thermal stresses show that the LBH trend is not explained by the conventional cracking mechanism.Simulations suggest that part thickness affects stress distribution leading to more substantial distortion and consequent failure to add layers for continued fabrication of thinner parts.