Sustainable all-solid elastocaloric cooler enabled by non-reciprocal heat transfer

Non-reciprocal heat transfer has the potential to shape the landscape of high-performance solid-state elastocaloric cooling technology as an eco-friendly alternative of traditional vapour-compression refrigeration with environmental issues. However, neither the working principle nor the technical route of combining non-reciprocal heat transfer with solid-state caloric cooling system is clear. Here we establish a framework for the development of non-reciprocal heat-transfer-enabled solid-state elastocaloric devices. We first illustrate theoretically that the thermal rectification ratio of non-reciprocal heat transfer unit is strongly correlated with the elastocaloric cooling performance. We further build an all-solid-state elastocaloric cooler prototype incorporated with a meta-material designed non-reciprocal heat transfer unit for efficient heat transfer and stable operations. With a thermal rectification ratio of 6.5, the cooler exhibits cooling power of 174.8 mW corresponding to a cooling heat flux of 242.8 mW cm−2. The cooler with non-reciprocal heat transfer units survives a long device-level operational fatigue life of over 2 million cycles without failure under the buckling-resistant compressive loading. Our work suggests new space for the design of next-generation cooling systems embracing sustainability. Elastocaloric cooling has emerged as an eco-friendly technology with low greenhouse gas emissions and high energy efficiency. Here the all-solid-state elastocaloric cooler shows a long operational life of over 2 million cycles.