Carbon Spherogel Monoliths for Electrochemical Applications

Carbon materials featuring very high porosity are very important for applications as electrodes in energy storage devices, as support material in catalysis, or as effective separation medium or filtration. They reach porosity values up to 99%, specific surface areas of up to 2500 m 2/g, they are chemical predominantly inert and additionally electrical conductive. The density and porosity characteristics of carbon aerogels can be tailored very precisely by adjusting the synthesis parameters or supercritical drying conditions of the organic precursors. In 2019, we established a new class of carbon aerogels: carbon spherogels. These spherogels consist of interconnected carbon hollow spheres derived from a polymer templating process. Typically, the hollow spheres have an interior diameter of 250 nm and a carbon shell thickness of around 20 nm. The thickness of the shell and the sphere diameter can be controlled and varied very well. Also, the porosity of the sphere shell, containing pores in the micropore range (<2 nm), can be easily adjusted. These pores allow access to the sphere interior. Such hollow sphere systems are promising since the interior void space can be loaded with additional, for instance, inorganic guest species. Thus, we can benefit by encapsulating catalytically active materials or high-performance battery species or by using the interior space as a microreactor. In this way, we can combine an electrochemical function of the loaded species with the high electrical conductivity of the carbon sphere scaffold. Compared to other strategies for hybrid carbon materials, we can solely deposit the loading within the enclosed, protected sphere interior. Our project deals with a profound investigation of the synthesis and related properties of such hybrid carbon spherogels. We will use different species (metal oxides, noble metals, silicon) for encapsulation and concomitantly vary the carbon pore structure. This will allow us to gain deep insights into optimized synthesis conditions on important structure properties relations for applications in energy storage systems (supercapacitors, lithium-ion batteries). For such energy storage applications, additional factors may play an important role: cycle stability and mechanical and chemical stability of the material.