Pengcheng Zhu,Xuepeng Luo,Xinran Lin,Zhichong Qiu,Rongrui Chen,Xiangcheng Wang,Yaling Wang,Yuan Deng,Yanchao Mao
Flexible thermoelectric devices (f-TEDs) can realize direct energy conversion between heat and electricity, which hold great prospects in wearable power source and personal thermal management. However, conventional f-TEDs made from intrinsically flexible thermoelectric materials have low power density, and elastomer sealed bulk thermoelectric materials-based f-TEDs can hardly achieve active cooling. Additionally, these f-TEDs usually are not self-healable and recyclable, which easily occur fractures in wearable applications. Here, we developed a self-healable and recyclable f-TED by integrating dynamic covalent thermoset polyimine with liquid metal and thermoelectric legs. This f-TED achieves a normalized power density of 1.54 μW·cm −2 ·K −2 , and can deliver a record 13.8 °C on-body cooling effect with a high coefficient of performance (COP) at 3.91 under 7 °C temperature difference, which leads to a low power consumption of ∼ 38 W for the cooling of regular human body. Based on the f-TED, we further developed a personal thermal management system, which can keep body within comfort zone at different surrounding temperatures, also realize healthcare function for fever or sprained ankle. Compared with conventional thermoelectric devices, this f-TED can simultaneously achieve self-healability, recyclability, flexibility, large normalized power density, and high on-body cooling effect with low power consumption. Such f-TED could open up new opportunities to develop devices for wearable energy harvesting and personal thermal management.
Herein, nitrogen-doped carbon (NC) encapsulated CoP hollow spheres are designed and prepared through a sodium L-aspartate assisted carbonization-oxidation-phosphorization route. Experimental and theoretical analysis unveil that the encapsulating of NC results in improved electric conductivity and enhanced electrolyte wettability. Particularly, an interfacial charge redistribution induces the establishment of local electric field at the CoP/NC interface, which leads to a decrease in surface OH – adsorption energies, an enhancement in charge transfer efficiency between OH – and active materials, and a reduction in OH – diffusion energy barriers. Thus, the CoP@NC electrode materials demonstrate enhanced capacity values (998C g −1 at 2 A g −1 and 640C g −1 at 20 A g −1 ) and cyclic stability (a capacity retention of 92.7 % after 5000 cycles). Moreover, three-dimensional macroporous N-doped carbon foams (MNCFs) are prepared through a facile and eco-friendly strategy using sodium L-aspartate as N-containing carbon source. Such MNCFs possess large surface area, enhanced electrical conductivity, and high-efficiency mass and ion transport, thus achieving specific capacitances of up to 426F g −1 at 1 A g −1 and 325F g −1 at 10 A g −1 . Furthermore, the fabricated CoP@NC||MNCFs hybrid supercapacitor device delivers an energy density of up to 75.1 Wh kg −1 at 800 W kg −1 , and demonstrates a capacity retention of 93.8 % after 5000 cycles. Our work not only provides valuable insights but also opens new avenues for designing and constructing advanced electrode materials for high-efficiency energy storage applications.
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