Lithium ion mediated competitive mechanism in polymer solution for fast phase-inversion toward advanced porous electrode materials

Abstract

Designing micro- and nanostructures of carbon materials is intriguing from both the aspects of fundamental science and of engineering. The structure of carbon precursors exerts a decisive impact on the structure and performance of carbon materials. When polymers serve as carbon precursors, their aggregated state structures determine the specific surface area and pore structure of porous carbon. This paper presents a brand-new strategy for regulating the aggregated state structure of polyacrylonitrile through solvation of lithium ions and investigates the influence of the strength of solvation on the aggregated state structure and porous carbon structure. This regulation process does not exhibit a linear trend. The prepared porous carbon is applied as electrode materials for the negative electrodes of supercapacitor. It is discovered that during this solvation regulation process, a competitive relationship is formed with the other three forces in the solution, ultimately affecting the solvent bridge structure and phase transformation rate of polyacrylonitrile. When the concentration of lithium chloride reaches a nearly saturated level of 10 %, the capacity of the porous carbon can increase to 322.8 F g^-1, which demonstrates excellent cycling stability. To explore the universality of this strategy in regulating the carbon structure, the material is also employed as the negative electrode of sodium-ion batteries.