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Lithium–sulfur batteries are among the promising high‐capacity candidates owing to the superior theoretical capacity of sulfur, when compared with conventional cathodes such as LiCoO₂. However, several issues must be addressed before these batteries can be considered fully operational. Major issues regard the insulating nature of sulfur and the so‐called shuttle effect of soluble polysulfides, which dramatically reduces the cathode capacity upon cycling. Herein, three carbon‐containing polymer‐derived ceramic aerogels are characterized belonging to the Si‐C‐O and Si‐C‐N systems, infiltrated with sulfur to work as cathodes for Li‐S batteries. The electrochemical performances are evaluated in relation to the microstructural and chemical features of such materials. In particular, the effect of the pore size of the ceramic matrices on the shuttling behavior of polysulfides is investigated. Despite the high initial specific capacities exceeding hundreds of mAh g⁻¹, all types of cathodes show stable capacities in the 60–120 mAh g⁻¹ range after 100 cycles.

As one of the promising candidates for future energy storage, lithium sulfur batteries have attracted much attention due to their superior energy density and low production cost as compared with that of conventional Li ion batteries. However, the obstacles such as insulated nature, volume expansion and “shuttle effect” significantly hamper the practical commercial application of lithium sulfur batteries. Designing and building novel sulfur cathodes with conductive micro-nanostructure is one of the potential ways to solve the issues of lithium sulfur batteries. C-rich ceramic matrices provide an ideal conductive skeleton for the sulfur host due to their electronic conductivity and robust, stress accommodating mechanical properties. This dissertation presents facile and cost-effective methods for the preparation of C-rich silicon carbonitride (SiCN) ceramics, Silicon oxycarbide (SiOC) ceramics and SiCN-boron nitride (SiCN-BN) composites to be utilized as sulfur host materials for the cathode in lithium sulfur batteries to enhance their electrochemical performance. First of all, porous C-rich SiCN ceramic matrices were synthesized by crosslinking of silicon-based polymers and subsequent pyrolysis in a temperature range between 1000 ℃ and 1600 ℃ under argon. Through the melting-diffusion technique at 155 ℃, sulfur was successfully embedded in the obtained porous ceramic matrices. After the characterization and performance testing, the impact of the initial porosity and elemental composition of the SiCN ceramics on the electrochemical performance of SiCN-S composites is addressed. It is shown that the material pyrolyzed at 1000 °C reveals a mesoporous character in line with the presence of a free carbon phase dispersed in the SiCN matrix and demonstrates the best electrochemical stability and the highest capacity (more than 310 mAh/g over 40 cycles) at a high sulfur content of 66 wt.%. To investigate the electrochemical performance of the C-rich SiCN ceramics pyrolyzed a

As a promising matrix material for anchoring sulfur in the cathode for lithium-sulfur (Li-S) batteries, porous conducting supports have gained much attention. In this work, sulfur-containing C-rich SiCN composites are processed from silicon carbonitride (SiCN) ceramics, synthesized at temperatures from 800 to 1100 °C. To embed sulfur in the porous SiCN matrix, an easy and scalable procedure, denoted as melting-diffusion method, is applied. Accordingly, sulfur is infiltrated under solvothermal conditions at 155 °C into pores of carbon-rich silicon carbonitride (C-rich SiCN). The impact of the initial porosity and microstructure of the SiCN ceramics on the electrochemical performance of the synthesized SiCN-sulfur (SiCN-S) composites is analysed and discussed. A combination of the mesoporous character of SiCN and presence of a disordered free carbon phase makes the electrochemical performance of the SiCN matrix obtained at 900 °C superior to that of SiCN synthesized at lower and higher temperatures. A capacity value of more than 195 mAh/g over 50 cycles at a high sulfur content of 66 wt.% is achieved.