Intricate ceramic bronze-casting moulds are among the most significant archaeological remains found at Bronze Age metallurgical workshops in China. Firing temperature was presumably one of the most important technical factors in mould making. However, it has proven difficult to determine the firing temperatures of excavated moulds using existing analytical methods. This study establishes an innovative new method for using Fourier-transform infrared spectroscopy (FTIR) to estimate the firing temperature of clay-containing remains. The method is based on the finding that the infrared absorptivity of fired clay minerals, measured at the Si–O–Si stretching resonance band, is negatively correlated with firing temperature. Moulds and mould cores dating to the Early Shang period (sixteenth to fourteenth century BCE) are found to have been fired at extremely low temperatures—as low as 200–300 °C in many instances. These results provide critical new data for understanding the metallurgical technology of ancient China.

Several ionic organic compounds have been employed as additives of the V(V) electrolyte for vanadium redox flow battery (VRB) to improve its stability and electrochemical activity. Stability of the V(V) electrolyte with and without additives was investigated with ex-situ heating/cooling treatment over a wide temperature range of -5 °C to 60 °C. It was found that cationic organic compounds could significantly improve the stability of the V(V) electrolyte at a wide range of temperature. Their electrochemical behavior in the V(V) electrolyte were further studied by cyclic voltammetry (CV) and steady state polarization. The results showed that the electrochemical activity, including the reversibility of electrode reaction, the diffusivity of V(V) species, polarization resistance of V(V) species, the polarization resistance and the flexibility of charge transfer for the V(V) electrolyte with these 2 additives was all improved compared with the pristine solution. The VRB employing positive electrolyte with cationic organic compounds as additive exhibited excellent charge-discharge behavior with an average energy efficiency of more than 80% at a current density of 20 mAcm -2 . XPS spectra illustrated that the addition of CHPTAC introduced more oxygen-containing and nitrogen-containing functional groups, which improved the electrochemical performance and cycling stability of VRB.

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