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Exploiting cationic vacancies for increased energy densities in dual-ion batteries

journal contribution
posted on 10.12.2019 by Toshinari Koketsu, Jiwei Ma, Benjamin J Morgan, Monique Body, Christophe Legein, Pooja Goddard, Olaf J Borkiewicz, Peter Strasser, Damien Dambournet
© 2019 Elsevier B.V. Dual-ion Li–Mg batteries offer a potential route to cells that combine desirable properties of both single-ion species. To maximize the energy density of a dual-ion battery, we propose a strategy for achieving simultaneous intercalation of both ionic species, by chemically modifying the intercalation host material to produce a second, complementary, class of insertion sites. We show that donor-doping of anatase TiO2 to form large numbers of cationic vacancies allows the complementary insertion of Li+ and Mg2+ in a dual-ion cell with a net increase in cell energy density, due to a combination of an increased reversible capacity, an increased operating voltage, and a reduced polarization. By tuning the lithium concentration in the electrolyte, we achieve full utilization of the Ti4+/Ti3+ redox couple with excellent cyclability and rate capability. We conclude that native interstitial sites preferentially accommodate Li+ ions, while Mg2+ ions occupy single-vacancy sites. We also predict a narrow range of electrochemical conditions where adjacent vacancy pairs preferentially accommodate one ion of each species, i.e., a [LiTi ​+ ​MgTi] configuration. These results demonstrate the implementation of additional host sites such as cationic sites as an effective approach to increase the energy density in dual-ion batteries.

Funding

French National Research Agency under Idex@Sorbonne University for the Future Investments program (No. ANR-11-IDEX-0004-02)

Sino German TU9 network for electromobility” under the grant reference number 16N11929.

U.S. DOE under Contract No. DE-AC02-06CH11357

Royal Society (Grant No. UF130329)

Faraday Institution (faraday.ac.uk; EP/S003053/1, grant number FIRG003).

History

School

  • Science

Department

  • Chemistry

Published in

Energy Storage Materials

Volume

25

Pages

154-163

Publisher

Elsevier BV

Version

AM (Accepted Manuscript)

Rights holder

© Elsevier

Publisher statement

This paper was accepted for publication in the journal Energy Storage Materials and the definitive published version is available at https://doi.org/10.1016/j.ensm.2019.10.019

Acceptance date

16/10/2019

Publication date

2019-10-24

Copyright date

2020

ISSN

2405-8297

eISSN

2405-8297

Language

en

Depositor

Dr Pooja Goddard Deposit date: 7 December 2019

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