首页|The initial stages of Li2O2 formation during oxygen reduction reaction in Li-O2 batteries:The significance of Li2O2 in charge-transfer reactions within devices

The initial stages of Li2O2 formation during oxygen reduction reaction in Li-O2 batteries:The significance of Li2O2 in charge-transfer reactions within devices

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Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device with high cyclability.Problems with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowl-edge of its mechanisms,especially when devices are concerned,hinders further development.From this perspective,the present work uses operando Raman experiments and electrochemical impedance spec-troscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product sig-nal(Li2O2)was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic model.The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants.While the time constant for the anode interface reveals to remain rel-atively constant after the first discharge,its surface seemed to be more non-uniform.The model indicated that the reaction occurs at the Li2O2 surface,decreasing the associated resistance during the initial dis-charge phase.Furthermore,the growth of Li2O2 forms a hetero-phase between Li2O2/electrolyte,while creating a more compact and homogeneous on the Li2O2/cathode surface.The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

Li-O2 batteryOperando Raman analysisEquivalent circuit modelingTime-constant distribution

Daniela M.Josepetti、Bianca P.Sousa、Simone A.J.Rodrigues、Renato G.Freitas、Gustavo Doubek

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Advanced Energy Storage Division,LAB,Center for Innovation on New Energies,School of Chemical Engineering,University of Campinas,Av Albert Einstein 500 13083-852,Campinas,SP,Brazil

Institute of Physics & Department of Chemistry,Laboratory of Computational Materials,Federal University of Mato Grosso,78060-900,Cuiabá,MT,Brazil

S?o Paulo Research Foundation(FAPESP)ShellANP(Brazil's National Oil,Natural Gas and Biofuels Agency)support from the Brazilian Coordination for the Improvement of Higher Education and Personnel(CAPES)CNPq(PQ-2)UFMT STI-Server

2017/11958-1Process 304442/2019-4

2024

10.1016/j.jechem.2023.09.034

能源化学
中国科学院大连化学物理研究所 中国科学院成都有机化学研究所

能源化学

CSTPCDEI
影响因子：0.654
ISSN：2095-4956
年,卷(期)：2024.88(1)
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