离子热合成锰基氧化物及其可逆储热性能

Ionic Thermal Synthesis and Reversible Heat Storage Performance of Manganese-based Oxides

光热电站需要配备大规模高温储热模块,金属氧化物可以通过可逆氧化还原反应实现热量的存储与释放。其中锰基氧化物无毒、廉价,极具潜力,但可逆性较差。为此,本研究采用深共溶溶剂离子热合成了锰基氧化物,探索了合成参数和铁掺杂对其储热性能的影响。离子热合成的MnCO_(3)前驱体在高温下分解释放CO_(2),使锰基氧化物具有丰富的孔隙结构,为氧气的传输与扩散提供通道,有利于氧化还原反应。离子热合成的Mn_(2)O_(3)比商业Mn_(2)O_(3)反应性能好,但其氧化反应速度较慢;合成温度150℃、掺杂20%Fe的锰铁氧化物的氧化速率快,储热密度高达300.66 J/g,反应可逆性最佳,可实现长期稳定循环。离子热合成策略可以增加锰氧化物中晶格氧占比,促进氧空位的迁移,从而提高可逆性和循环稳定性。

Concentrated solar power plant needs to be equipped with large-scale high-temperature heat storage module.Metal oxides can store and release heat through reversible redox reaction.Manganese oxides is non-toxic and cheap,showing great potential for applying in solar power plant,but it displays poor reversibility.Here,a manganese-based oxides with high reversibility by deep eutectic solvent(DES)ionic thermal synthesis was proposed,and effects of synthesis parameters and iron doping on heat storage performance were studied.MnCO_(3),as the raw material,was used to produce manganese oxides by ionic thermal decomposition at high temperature and released CO_(2),which could also form abundant pore structure,providing great channels for oxygen transmission and diffusionfor redox.Although this Mn_(2)O_(3)synthesis method showed better reactivity than commercial Mn_(2)O_(3),its oxidation rate was low.It is worth noting that oxidation rate of manganese iron oxide doped with 20%Fe,synthesized at 150℃,was fast.Its heat storage density reached 300.66 J/g,and reversibility of the reaction was the best,which could realize long-term stable cycle.Our results demonstrated that ionic thermal synthesis can increase the lattice oxygen ratio in manganese oxides,promoting migration of oxygen vacancies,and further improving reversibility and cyclic stability.