A Dual Modification Method to Prepare Carbide Slag into Highly Active CaO-Based Solar Energy Storage Materials

Carbide slag is a solid waste with high calcium content that is generated from acetylene production. To achieve efficient resource utilization of carbide slag, this work mainly adopts a dual modification method that combines the doping of inert substances with wet mixing of acetic acid to convert carbide slag into highly active CaO-based energy storage materials. Because of the addition of acetic acid and inert dopants, the energy storage performance of the composite material is significantly enhanced. After 20 cycles, the carbonization conversion rate and energy storage density of the dual-modified composite material (AC-CMZ75) are 0.79 and 2500 kJ/kg, which are 1.88 and 3.29 times higher than those of the acetic acid single-modified (AC-CS) and pure carbide slag materials (W-CS), respectively. In addition, the average grain size of CaO in the dual-modified composite material increases slowly and has a richer pore structure, which is beneficial for alleviating the sintering phenomenon of CaO in the carbide slag. Therefore, compared to pure carbide slag materials, the dual-modified composite materials are more resistant to sintering during long-term calcium cycling, exhibiting better energy storage performance and cycling stability.