1,3,5-trioxane (TOX), formaldehyde (FA), and water can form an azeotropic system at atmospheric pressure, which causes the TOX produced by reactive distillation to consume a lot of energy to obtain a high-purity TOX product through the subsequent separation and purification process. Therefore, four inorganic salts (MgSO4, MgCl2, CaCl2, and the mixture of MgCl2 and CaCl2) were selected as extractive distillation agents to investigate the effects of inorganic salts on the azeotropic system of TOX + FA + water. Isobaric vapor–liquid equilibrium data were obtained by the experiments on TOX + FA + water and TOX + FA + water + salt at atmospheric pressure. The experimental results show that the addition of inorganic salts can effectively change the azeotropic composition, so that the mass fraction of TOX in the azeotropic system increases from 70.22% to a maximum of 80.66%, which can significantly reduce the energy consumption required for subsequent the separation and purification process. Finally, the data were fitted and correlated with the extended UNIFAC model. The correlation was very consistent with the experimental results, indicating that the extended UNIFAC model has good applicability to the system.
The practical application of lithium metal batteries is hindered by the heterogeneous solid-electrolyte interphase (SEI), which undergoes repeated cracking and reconstruction during cycling, thereby exacerbating lithium dendrite growth. To address this issue, we propose an in-situ reconstruction strategy for the SEI layer by introducing the functional additive 1,3,5-trioxane (TO), which helps to homogenize lithium transport and enhance mechanical stability. By participating in the Li + solvation structure, TO facilitates the formation of a homogeneous and mechanically robust SEI, which preferentially promotes the formation of a polyoxymethylene (POM) phase and enriches LiF content within the SEI. This tailored interface significantly improves the uniformity of lithium deposition and interfacial compatibility. In coin cells employing a high-loading LiNi 0.90 Co 0.05 Mn 0.05 O 2 cathode (7.37 mg cm − 2 ) and an ultrathin lithium anode (50 μm), the TO-modified electrolyte enables a capacity retention of 73.1% after 200 cycles at 0.5 C, substantially outperforming the conventional electrolyte that retained only 25.9%. These results demonstrate the promising potential of this electrolyte design for high-energy-density lithium metal batteries.
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