R. Amin
Oak Ridge National Laboratory,
United States
Keywords: seawater battery, Zn-air battery, Long duration, chalcogel
Summary:
Cost is an important parameter for viable and sustainable industrial deployment of energy storage systems for long duration applications. We focus on developing the cost-effective batteries by utilizing seawater and gel polymer electrolyte for seawater and Zn-air batteries, respectively. The electrolyte membrane and electrocatalyst play a crucial role for the cell performances. We developed polymer and ceramic membranes for these battery systems that can sustain with harsh conditions. We also synthesized cost-effective catalyst materials by easy scale up process which exhibits excellent performance for oxygen evolution and reduction reactions that plays crucial role for cell kinetics at cathode compartment. Also, we present a porous, amorphous, sulfide-based MnxMo3S13 chalcogel, which concurrently offers high capacity and cycle stability. The solution-processable room temperature synthesized MnxMo3S13 (x~0.25) chalcogel exhibits a local structure that resembles the Mo3S13 cluster with Mn2+ distributed across the Mo3S13 matrix, as determined by synchrotron X-ray pair distribution function (PDF) and extended X-ray absorption fine structure (EXAFS). Ab initio molecular dynamic (AIMD) simulations reveal that Mn2+ incorporation shortens the polysulfide chain in the gel matrix compared with Mo3S13 chalcogel while forming a coordination environment with disulfide groups, analogous to the experimental findings. A Li/Mn0.25Mo3S13 half-cell delivers 897 mAh g-1 capacity during the first discharge and retains 571 mAh g-1 capacity after 100 cycles at a C/3 rate. Distribution of relaxation time (DRT) unveils a stable solid-electrolyte interphase (SEI) formation upon cycling that enables charge-discharge reversibility. Here, the enhanced capacity retention and cycle stability compared to Li/Mo3S13 cell are attributed to the reduced dissolution of active mass into the electrolyte, facilitated by the formation of shorter polysulfide chains within the Mn0.25Mo3S13 structure and the strong affinity of Lewis-acidic Mn²⁺ for polysulfide anions generated during the charge-discharge process of the Li/Mn0.25Mo3S13 cell. Thus, this presentation illustrates a design principle of materials for high-capacity and cycle-stable energy storage systems by cost-effective approaches.