Strontium chloride nanofiber composites for ammonia storage and delivery

Abstract

Solid-state ammonia storage supports the transition towards safe and efficient low-carbon energy storage and transportation. Alkaline earth metals halides (AEMHs) based materials, such as strontium chloride (SrCl₂), can be utilized to efficiently store ammonia with high capacity and mitigate ammonia toxicity but suffer from large volume expansion during ammonia absorption and slow thermal desorption kinetics. Here, SrCl₂ was structured into SrCl₂-carbon nanofiber composites (SrCs) by electrospinning and a subsequent three-step carbonization process. Polyvinylpyrrolidone (PVP) was used as a carrier polymer in water/ethanol solution in electrospinning and as a carbon source for stabilizing SrCs with high SrCl₂ loadings. Chemical and structural changes of the nanofiber structures during carbonization were investigated with different surface characterization techniques, including XRD, SEM, and FTIR. The SrCs could be loaded with up to 90 wt% of SrCl₂ salt, resulting in remarkable high, and stable ammonia sorption uptake capacity of 671 mg/g over four cycles, mechanical integrity and more than 4 times faster desorption kinetics compared to SrCl₂ powder.