高温太阳能两步热化学循环分解H2O/CO2制备H2/CO是重要的太阳能热化学储能方式，但系统能量传输和转换过程的热损失和不可逆损失太大，导致太阳能到燃料实际转换效率低于6%，难以广泛应用。本研究涉及工程热物理和材料学等多学科领域交叉，采用理论分析、数值模拟和实验验证相结合的研究方式，基于能的梯级利用原理，从热力学角度揭示高温太阳能热化学循环制备燃料不可逆损失减少和能效提升机理。依次分析微观氧载体层面热力学规律、宏观反应器层面多物理场耦合机理，阐明两步太阳能热化学循环太阳能-热能-化学能高效转换机制；重点关注还原步氧分压降低过程不可逆损失减小机理，基于化学链循环建立“双循环”太阳能-热能-化学能耦合模型，据此提出太阳能热化学循环制备燃料能效提升新方法；研制高温太阳能热化学循环能效提升原理性实验装置，验证高温太阳能热化学循环能效提升机理和方法。研究成果将为太阳能热化学储能提供新的方法和思路。

The production of H2/CO from H2O/CO2 splitting by two-step thermochemical cycle of high-temperature solar energy is an important method for solar thermochemical energy storage. However, the heat loss and irreversible loss of the system's energy transmission and conversion process are too large, resulting in the actual solar-to-fuel conversion efficiency lower than 6% and limiting its wide application. This study involves interdisciplinary fields of engineering thermophysics and materials science, etc. It uses a combination of theoretical analysis, numerical simulation and experimental verification. Based on the principle of energy cascade utilization, the mechanisms of reducing the irreversible loss of fuel production by high-temperature solar thermochemical cycle and improving its solar-to-fuel conversion efficiency are revealed from the perspective of thermodynamics. The thermodynamic laws at the micro-oxygen carrier level and the multi-physics field coupling mechanism at the macro-reactor level will be analyzed in order to clarify the solar-thermal-chemical energy conversion mechanism of the two-step solar thermochemical cycle; Focusing on the irreversible loss reduction mechanism of the reduction step in order to decrease the oxygen partial pressure, a “dual-cycle” solar-thermal-chemical energy coupling model will be established based on chemical-looping cycle, and a new method for improving the energy efficiency of solar thermochemical cycle fuel production will be proposed; This project will develop the principle experimental device of high-temperature solar thermochemical cycle to verify its energy-efficiency improvement mechanism and method. Research results will provide new methods and ideas for solar thermochemical energy storage.