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In order to find out the optimal concentration of ionic liquid to lower the cost of inhibiting coal spontaneous combustion, effects of aliphatic hydrocarbons, hydrogen bonds, and some structural parameters of coal samples treated with low‐concentration ionic liquids were analyzed through Fourier‐transform infrared spectroscopy (FTIR) and temperature‐programmed experiments. Meanwhile, the changes of index gases in the heating process were observed by the temperature‐programmed method. The results show that the contents of aliphatic hydrocarbons in the treated coal samples decrease remarkably, so does the length of aliphatic chain CH2/CH3; besides, the amount of CO produced also decreases to some extent. When the mass concentration ratio is 1:10, HB‐tc, BB‐tc, AC‐tc, and BN‐tc can reduce the spatial structure and enhance the structural stability of aromatic clusters in coal. The CO concentrations of 1:2 HB‐tc and 1:10 AC‐tc are obviously lower than that of raw coal, indicating their better inhibitory effects. The inhibitory effect of HB‐tc decreases with the decrease in concentration. With the rise of temperature, the effect of concentration on the inhibition of CO production gradually weakens at 180°C and 200°C. AC‐tc achieves the optimum inhibitory effect near 1:10 mass concentration ratio.

When a high-water-cut physical inhibitor (HWPI) is sprayed on the coal in goaf, moisture in coal will undergo a substantial reduction under the influence of liquid flow and water evaporation, which severely weakens the inhibitory effect of the HWPI and greatly shortens its inhibitory lifetime. Therefore, this paper proposes a thermoresponsive secundine inhibitor (TSI) to solve the problem of poor water retention and short inhibitory lifetime by sealing the HWPI in thermoresponsive secundine. Before the ambient temperature (30 °C) reaches the trigger temperature, the water retention rate of the TSI is 100%. After the trigger temperature is reached, the TSI will quickly release a large amount of the HWPI to suppress coal spontaneous combustion. The releasing time and trigger temperature of the TSI drop rapidly with the increase of the borehole diameter and borehole number, while its weight loss grows with the increase of the borehole diameter and borehole number. The experimental results reveal that the borehole diameter of 2.5 mm and the borehole number of 12 are the optimal conditions for the TSI to release more HWPI in a relatively short period of time.