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Combining in situ electrochemistry, operando FTIR and post-mortem analyses to understand Co-Mn-Al spinels on mitigating shuttle effect in lithium-sulfur battery

2023; Elsevier BV; Volume: 116; Linguagem: Inglês

10.1016/j.nanoen.2023.108809

2211-3282

Érick A. Santos, Chayene G. Anchieta, Rodolfo Castanho Fernandes, Manuel Jonathan Pinzón Cárdenas, André N. Miranda, Isabela Galantini, Francisco C. B. Maia, Gustavo Doubek, Cristiane B. Rodella, Leonardo M. Da Silva, Hudson Zanin,

Thermal Expansion and Ionic Conductivity

The spinel oxide Co2Mn0.5Al0.5O4 (CMA) was investigated as an additive onto the cathode of lithium-sulfur batteries. We demonstrate the polysulfide adsorption onto CMA, mitigating the shuttle effect, a well-known failure mechanism. The in situ electrochemical impedance spectroscopy and cyclic voltammetry tests evidenced that CMA facilitates the conversion of short-chain lithium polysulfides (LPS). The CMA reduced the maximum voltammetric current by approximately 20% compared to the AC/S cathode and facilitates the conversion of LPS into solid-liquid-solid species. High conversion efficiencies were verified after 315 cycles, resulting in 89% of capacity retention. Low CMA concentrations of up to 10 wt.% increased battery capacity and showed that CMA has high ionic conductivity, while moderate concentrations of approximately 50 wt.% improved cyclability but increased cell's resistivity. This improvement in cyclability is related to LPS trapped at CMA which is demonstrated by micrographs, X-ray energy dispersive and photoelectron spectra of post-mortem samples. The byproducts formed after cycling until failure, were identified by Raman spectra and diffraction patterns. Fourier transform infrared spectroscopy operando analyses suggested electrolyte decomposition as a relevant cell failure mechanism. In conclusion, we demonstrated how CMA can trap LPS and enhanced initial capacity to 1000 mA h g-1sulfur cm-2 and improved cyclability for more than ∼360 cycles.