UC Riverside

This work is an investigation of lithium sulfide carbon (Li2S@C) composites synthesis via Aerosol Spray Pyrolysis (ASP). These composites comprise the active portion of a cathode for a Li-Li2S battery, designed to outperform state of the art Li-ion cells in specific capacity (mAh/g). Producing these composites with ASP taps into the flexibility, product homogeneity and scalability of the system. This project hopes to bridge the gap between promising laboratory scale demonstrations and a commercially viable product.

The key concept of this project is the rationally designed Li2S@C composite microstructure, which consists of nano-scale Li2S particles uniformly encapsulated in a carbon matrix. We propose ASP as the synthesis method due to its unique operational mechanism: reactant precursors are atomized as aerosol so that each reactant particle is an individual micro-reactor. Operation in micro-reactor scale offers negligible heat and mass transport lags, dramatically improving kinetics and microstructure control.

Three different Li2S precursors are investigated; lithium nitrate, lithium carbonate and lithium acetate, respectively with sucrose as the carbon precursor. Effective Li2S-C cathodes have been produced from these three systems and each system delivers subtle microstructure and compositional differences, performing differently as a result. Lithium nitrate and sucrose derived particles appear to perform better in C/5 charging, with a specific capacity of 424 mAh/g after 40 cycles, with a capacity degradation of 0.00156. Whereas lithium carbonate and sucrose derived particles perform better in C/10 charging, with a specific capacity of 438 after 40 cycles, with a capacity degradation of 0.000612. Suggesting differences in architecture, such as porosity, particle size and particle size distribution play a role in affecting performance at different charge rates.