Construction of biomass waste derived hierarchical porous biochar framework based lithium hydroxide composites for highly efficient and durable low temperature thermochemical heat storage

Abstract

By virtue of its prominent properties of remarkable storage capability, achievable long-lasting storage period and extraordinary energy retention performance, salt hydrate-based thermochemical heat storage materials have become one of the most viable options for the effective use of renewable energy. Herein, a brand-new LiOH composite is demonstrated by adopting the strategy of compositing LiOH into a biomass waste-derived hierarchical porous biochar matrix and systematically characterized. The as-formed composites have exceptional hydration behavior while demonstrating superb storage capability up to 1865.7 kJ kg −1 attributed to the hierarchically porous framework with a large surface area. Furthermore, the LiOH composite with dramatically boosted thermal conductivity is able to achieve 91% energy retention after 15 cycles, elucidating its terrific cycle reliability as well as distinguished heat transfer properties. This research not only provides a valuable approach to synthesize the superb biochar materials and make the most of low-grade thermal energy, but may also inspire new ideas of turning waste into treasure to solve the predicament of renewable energy storage . • Biomass waste derived biochar framework is fabricated through a two-stage activation. • The biochar host matrix presents ultrahigh surface area with diversified porosity. • Li/BCM1(K4) exhibit remarkable storage capability and hydration performance. • Li/BCM1(K4)-40 shows excellent cycle reliability and heat transfer properties.