A new mixed organic acid of citric acid and salicylic acid is proposed to recover valuable Co and Li ions from spent LIBs. Under the optimum leaching conditions, the leaching efficiencies of Co and Li ions can reach 99.5% and 97%.

Propane–1,2,3-triol-loaded polysulfone (PSF) microcapsules were prepared by the solvent evaporation method. The particle size of the microcapsules is about 140 μm. The shell wall thickness is about 17 μm approximately. The microcapsules have high thermal stability and antiwear performance. The self-healing coating was prepared by adding the prepared capsule into the epoxy resin coating. After electrochemical and corrosion immersion experiments, the resistance modulus of the coating added to the microcapsules was higher than the others in a 3.5 wt % NaCl corrosion solution, and it had the lowest corrosion current density, so the self-healing microcapsule coatings showed excellent healing ability and corrosion inhibition function for microcracks. This was attributed to the formation of a hydrophobic film after propane–1,2,3-triol was released from the damaged microcapsules.

PEMFC are considered to be the most promising for automotive energy because of their good working effect, low temperature, high efficiency, and zero pollution. Stainless steel as a PEMFC bipolar plate has unparalleled advantages in strength, cost, and processability, but it is easy to corrode in a PEMFC working environment. In order to improve the corrosion resistance, the surface modification of 316L stainless steel is a feasible solution for PEMFC bipolar plates. In the present study, the plasma-nitrided coating and CrNx coating were prepared by the plasma-enhanced balanced magnetron sputtering technology on the 316L stainless steel surface. The microstructures, phase compositions, and corrosion resistance behavior of the coatings were investigated. The corrosion behavior of the prepared plasma-nitrided coating and CrNx coating was investigated by potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy (EIS) in both cathodic and anodic environments. The experimental results show that corrosion resistance of the CrNx coating was better than the plasma-nitrided coating. It was indicated that the technology process of nitriding first and then depositing Cr was better than nitriding only.

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Many types of hard material are coated on the surface to improve their wear resistance. Addition of vanadium carbide to Co based alloys (stellite no. 21) as a hard material powder is one of the ways to improve the wear resistance characteristics of the surface layer. The plasma transfer arc (PTA) welding process was introduced as a coating technology for elevated temperature surface modification. This process has recently generated interest in the surface modification field owing to its operability, low initial cost of equipment, high deposition rate, and small dilution rate. Coated layers produced by PTA considerably improve the hardness and wear resistance of surface layers for elevated temperature applications. Vanadium carbide (VC) addition into stellite powder showed a significant improvement in wear resistance. However, alloys containing VC showed pronounced sensitivity to hot cracking under repeated heating and cooling environments. This study clarifies the cause of thermal fatigue cracking in Co based alloy deposits with VC powder additions. Cracks result from the difference in thermal expansion coefficient between the matrix and the carbides. Cracks initiate in the central part of the surface region and grow in a perpendicular direction towards the surface. The tendency for thermal fatigue crack initiation seems to increase with increasing carbide volume fraction and decrease as the volume fraction of the dendritic region decreases.