start-ver=1.4
cd-journal=joma
no-vol=8
cd-vols=
no-issue=29
article-no=
start-page=14472
end-page=14481
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200519
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Mechanisms for overcharging of carbon electrodes in lithium-ion/sodium-ion batteries analysed by operando solid-state NMR
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=A precise understanding of the mechanism for metal (Li and Na) plating on negative electrodes that occurs with overcharging is critical to managing the safety of lithium- and sodium-ion batteries. In this work, an in-depth investigation of the overlithiation/oversodiation and subsequent delithiation/desodiation of graphite and hard carbon electrodes in the first cycle was conducted using operando7Li/23Na solid-state NMR. In the 7Li NMR spectra of half cells of carbon electrodes and metal counter electrodes, three types of signals corresponding to Li dendrites that formed on the surface of graphite, hard carbon, and the counter electrode were distinguished from the signal of Li metal foil of the counter electrode by applying an appropriate orientation of the testing cell. For graphite overlithiation, the deposition of Li dendrites started immediately or soon after the minimum electric potential in the lithiation curve. In contrast, the deposition of Li dendrites in hard carbon started after the end of quasimetallic lithium formation for overlithiation at rates below 3.0C. Similar behaviour was also observed for the oversodiation of hard carbon. The formation of quasimetallic Li or Na in the pores of hard carbon serves as a buffer for the metal plating that occurs with overcharging of the batteries. Furthermore, some of the deposited Li/Na dendrites contribute to reversible capacities. A mechanism for the inhomogeneous disappearance of quasimetallic Li during delithiation of hard carbon is also proposed.
en-copyright=
kn-copyright=

en-aut-name=GotohKazuma
en-aut-sei=Gotoh
en-aut-mei=Kazuma
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YamakamiTomu
en-aut-sei=Yamakami
en-aut-mei=Tomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=NishimuraIshin
en-aut-sei=Nishimura
en-aut-mei=Ishin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=KometaniHina
en-aut-sei=Kometani
en-aut-mei=Hina
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=AndoHideka
en-aut-sei=Ando
en-aut-mei=Hideka
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=HashiKenjiro
en-aut-sei=Hashi
en-aut-mei=Kenjiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=ShimizuTadashi
en-aut-sei=Shimizu
en-aut-mei=Tadashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=IshidaHiroyuki
en-aut-sei=Ishida
en-aut-mei=Hiroyuki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

affil-num=1
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=

affil-num=3
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=

affil-num=4
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=

affil-num=5
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=

affil-num=6
en-affil=National Institute for Materials Science
kn-affil=

affil-num=7
en-affil=National Institute for Materials Science
kn-affil=

affil-num=8
en-affil=Graduate School of Natural Science & Technology, Okayama University
kn-affil=
END