Hjelm, Johan

Højberg, Jonathan

Knudsen, Kristian Bastholm

Mekonnen, Yedilfana Setarge

Mýrdal, Jón Steinar Garðarsson

Norby, Poul

Vegge, Tejs

Younesi, Reza

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 19, 2017The Influence of CO2 Poisoning on Overvoltages and Discharge Capacity in Non-aqueous Li-Air BatteriesMekonnen, Yedilfana Setarge; Knudsen, Kristian Bastholm; Mýrdal, Jón Steinar Garðarsson; Younesi,Reza; Højberg, Jonathan; Hjelm, Johan; Norby, Poul; Vegge, TejsPublication date:2013Link back to DTU OrbitCitation (APA):Mekonnen, Y. S., Knudsen, K. B., Mýrdal, J. S. G., Younesi, R., Højberg, J., Hjelm, J., ... Vegge, T. (2013). TheInfluence of CO2 Poisoning on Overvoltages and Discharge Capacity in Non-aqueous Li-Air Batteries. Postersession presented at Nordisk Batterikonferens 2013 (NORDBATT), Uppsala, Sweden.The Influence of CO2 Poisoning on Overvoltages and Discharge Capacity in Non-aqueous Li-Air Batteries Yedilfana S. Mekonnen1,2, Kristian B. Knudsen1, Jon S. G. Mýrdal1,2, Reza Younesi1, Jonathan Højberg1, Johan Hjelm1, Poul Norby1, Tejs Vegge1,2   1Department of Energy Conversion , Technical University of Denmark, Frederiksborgvej 399 Building 238, DK-4000 Roskilde, Denmark. 2Center for Atomic-scale Materials Design and Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.     References  1. McCloskey et al (2012).  J. Phys. Chem. Lett., 3, 997−1001. 2. Abraham, K. M.; Jiang, Z., J. Electrochem. Soc. 1996, 143, 1-5. 3. Gowda et al (2013). Phys. Chem. Lett., 4, 276−279. 4. Enkovaara et al (2010). J. Phys. Condens. Matter, 253202, 253202 5. Hummelshøj et al (2010). J. of Chem. Phys., 132, 071101. Fig3: a) Stepped Li2O2 surface. b) CO2 adsorbs at step. c) 1st LiO2 binds. d) 2nd LiO2 binds. e) 1st Li binds. f) 2nd Li binds to the surface; end up with 2 Li2O2  growth. Fig1. Energy densities of M-air wrt Gasoline.  Fig4: Free energy diagrams for discharge mechanism of Li2O2 on            Cathode surface with and without CO2.. Fig2: a) Discharge, b) Charge curves for pure & CO2 contaminated cells.  Introduction The Li-O2 couple is particularly attractive due to its high specific energy , ~5-10 times greater than currently available Li-ion batteries and mainly intended for onboard storage in vehicles.1 As first reported by Abraham et al. in 1996, the Li-O2 cell with aprotic solvent is shown to be rechargeable, when Li2O2 is formed during discharge.2 However, Li2CO3 is also formed from the parasitic reactions between the Li2O2 and aprotic electrolytes, air impurities (e.g. CO2) and the graphite.1 Both Li2O2 and Li2CO3 are insulating materials with wide band gap of 4.9 and 8.8 eV, respectively. Hence, these materials deposit (5-10 nm) limit the conductivity and lead to sudden death.3  Funded by ReLiable Project  a)  b)  Conclusions  CO2 is the most critical due to its high solubility in aprotic electrolytes & high reactivity with Li2O2 to form Li2CO3.   CO2 binds favorably at steps sites on Li2O2 surface and once it is adsorbed at the step site, it is unlikely to diffuse elsewhere.  The recharging process is strongly influenced by CO2, and exhibits  higher charging overvoltage, which is observed already at 1 % CO2 while at 50 % CO2 a large capacity loss is seen. Results  CO2 binds preferentially at step sites on the 11 00  Li2O2 surface and blocks the active nucleation sites.  Both DFT and experimental results show that, CO2 contamination strongly affects the recharging process.  Higher overvoltages and large capacity losses are observed at 50 % CO2. Methods  Li-air cells were constructed using a Swagelok design. Each cell contained LiTFSI, DME and P50 cathodes. Experiments were performed using a galvanostat.  DFT as implemented in GPAW code4 via ASE. RPBE approximation is used. The stepped 11 00  Li2O2 surface  with a super cell consisting of a 56-60 atoms slab with 18 Å vacuum layer and (4,4,1) kpoints are used. 

The Influence of CO2 Poisoning on Overvoltages and Discharge Capacity in Non-aqueous Li-Air Batteries

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The Influence of CO2 Poisoning on Overvoltages and Discharge Capacity in Non-aqueous Li-Air Batteries

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