Reaction mechanisms for the limited reversibility of Li–O2 chemistry in organic carbonate electrolytes
| Autor: | Kang Xu, Vilayanur V. Viswanathan, Jie Xiao, Silas A. Towne, Deyu Wang, Ji-Guang Zhang, Dehong Hu, Wu Xu, Zimin Nie, John S. Hardy |
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| Rok vydání: | 2011 |
| Předmět: |
Reaction mechanism
Renewable Energy Sustainability and the Environment Lithium carbonate Inorganic chemistry Energy Engineering and Power Technology chemistry.chemical_element Electrolyte chemistry.chemical_compound chemistry X-ray crystallography Carbonate Lithium Lithium oxide Electrical and Electronic Engineering Physical and Theoretical Chemistry Lithium peroxide |
| Zdroj: | Journal of Power Sources. 196:9631-9639 |
| ISSN: | 0378-7753 |
| Popis: | The Li–O 2 chemistry in nonaqueous liquid carbonate electrolytes and the underlying reason for its limited reversibility was systematically investigated. X-ray diffraction data showed that regardless of discharge depth lithium alkylcarbonates (lithium propylenedicarbonate (LPDC), or lithium ethylenedicarbonate (LEDC), with other related derivatives) and lithium carbonate (Li 2 CO 3 ) are constantly the main discharge products, while lithium peroxide (Li 2 O 2 ) or lithium oxide (Li 2 O) is hardly detected. These lithium alkylcarbonates are generated from the reductive decomposition of the corresponding carbonate solvents initiated by the attack of superoxide radical anions. More significantly, in situ gas chromatography/mass spectroscopy analysis revealed that Li 2 CO 3 and Li 2 O cannot be oxidized even when charged to 4.6 V vs. Li/Li + , while LPDC, LEDC and Li 2 O 2 are readily oxidized, with CO 2 and CO released from LPDC and LEDC and O 2 evolved from Li 2 O 2 . Therefore, the apparent reversibility of Li–O 2 chemistry in an organic carbonate-based electrolyte is actually an unsustainable process that consists of (1) the formation of lithium alkylcarbonates through the reductive decomposition of carbonate solvents during discharging and (2) the subsequent oxidation of these same alkylcarbonates during charging. Therefore, a stable electrolyte that does not lead to an irreversible by-product formation during discharging and charging is necessary for truly rechargeable Li–O 2 batteries. |
| Databáze: | OpenAIRE |
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