Screening of organic lithium precursors for producing high-performance Li4SiO4-based thermochemical energy storage materials: Experimental and kinetic investigations

Abstract

Thermochemical energy storage by using Li4SiO4 TCES materials has been considered a promising technology for efficient heat storage from high temperature sources (700–900 °C). It has been proven the utilization of organic lithium precursors could effectively improve the heat storage performance of derived Li4SiO4. Hence, in this work, 7 kinds of unreported organic lithium precursors were screened for producing high-performance Li4SiO4 TCES materials. The physicochemical properties, CO2 ad-desorption capacities and the heat storage/releasing performance of as-prepared Li4SiO4 were systematically evaluated by a series of experimental and kinetic investigations, and a dual modification effects of organic lithium precursor were revealed. As a consequence, 3 potential candidates including lithium benzoate, lithium oxalate and lithium citrate were screened out. Li4SiO4 adsorbents derived from these precursors show great heat storage amount promotions of over 50 % in comparison with the average capacity of traditional Li4SiO4 (~ 350 kJ/kg/cycle). Especially, the lithium citrate derived Li4SiO4 exhibits the greatest CO2 adsorption capacity, reaction rate and cyclic stability, leading to a cumulative storage amount of 5.9 MJ/kg within 10 cyclic heat storage/releasing processes. Above findings could provide guidance for the future development of high-performance Li4SiO4 materials and Li4SiO4-CO2 TCES systems.