Robust and flexible bacterial cellulose-based thermogalvanic cells for low-grade heat harvesting in extreme environments

Abstract

Harvesting the ubiquitous low-grade heat based on thermoelectric materials is an effective approach to ensure sustainable development. Quasi-solid thermogalvanic cell based on hydrogel has attracted considerable attention. However, challenge arise from the limited working temperature range and poor mechanical properties, thus severely restrict their long-term stability and application scenarios, especially under harsh environment. Herein, a robust, flexible and eco-friendly quasi-solid thermogalvanic cell is reported based on natural polymer bacterial cellulose confined with Fe(CN)63−/4− redox couple and hygroscopic salts. The as-fabricated bacterial cellulose-based thermogalvanic cell (BC-TGC) possesses excellent mechanical properties, exhibiting a tension strength of 3.4 MPa, a Young's modulus of 2.58 MPa and a high toughness of 644.6 KJ m−3. The introduction of hygroscopic salts (LiBr) endows the BC-TGC with excellent anti-drying and anti-freezing properties. The thermoelectric performance of BC-TGCs was investigated thoroughly, which could generate steady electricity under a small temperature gradient in a wide working range of −50 to 50 °C. The multifunctional applications of the BC-TGC were demonstrated, indicating that they could adapt to different temperatures and harsh environments, which greatly expanded the application scenarios of TGC. We expect that this study will provide an effective solution for portable, flexible and robust power supplies fabrication for low-grade heat harvesting.