/npsi/ctrl?action=rtdoc&an=9064981&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=9064981&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en
NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.jpowsour. 2007.06.103 Journal of Power Sources, 174, 2, pp. 883-888, 2007 Investigation of Li salt doped succinonitrile as potential solid electrolytes for lithium batteries Abouimrane, A.; Whitfield, Pamela; Niketic, Svetlana; Davidson, Isobel
AbstractSolid ionic conductors with good conductivity at room temperature and mechanical flexibility are very attractive candidates for application as electrolytes for secondary lithium batteries. Plastic crystal electrolytes formed by doping succinonitrile with lithium salts can potentially meet these requirements. In this study, succinonitrile doped with various lithium salts were characterized by differential scanning calorimetry, powder X-ray diffraction, conductivity measurements and in electrochemical studies. The much better conductivities and electrochemical performance of certain lithium salts in comparison to the others studied has been found to be correlated to their propensity to form crystalline adducts with succinonitrile at low molar concentrations. Of the lithium salts studied, only two which did not form crystalline adducts at low concentrations: lithium bistrifluoromethanesulphonylimide (Li[CF 3 SO 2 ] 2 N) and lithium tetrafluorborate (LiBF 4 ) had high enough conductivities at ambient temperature for evaluation in lithium cells. Contrary to prior predictions, both showed reasonable capacities, high coulombic efficiencies, and good capacity retention even with metallic lithium as the anode. Crown
Increasing the energy density of Li-ion batteries is very crucial for the success of electric vehicles, grid-scale energy storage, and nextgeneration consumer electronics. One popular approach is to incrementally increase the capacity of the graphite anode by integrating silicon into composites with capacities between 500 and 1000 mAh/g as a transient and practical alternative to the more-challenging, silicon-only anodes. In this work, we have calculated the percentage of improvement in the capacity of silicon:graphite composites and their impact on energy density of Li-ion full cell. We have used the Design of Experiment method to optimize composites using data from half cells, and it is found that 16% improvements in practical energy density of Li-ion full cells can be achieved using 15 to 25 wt% of silicon. However, full-cell assembly and testing of these composites using LiNi 0.5 Mn 0.5 Co 0.5 O 2 cathode have proven to be challenging and composites with no more than 10 wt% silicon were tested giving 63% capacity retention of 95 mAh/g at only 50 cycles. The work demonstrates that introducing even the smallest amount of silicon into graphite anodes is still a challenge and to overcome that improvements to the different components of the Li-ion battery are required.
The
conventional polyvinylidene fluoride (PVDF) binder works well
with the graphite anode, but when combined with silicon in composites
to increase the energy density of Li-ion batteries, it results in
severe capacity fade. Herein, by using scanning electron microscopy
and energy-dispersive X-ray spectroscopy analyses, we reveal that
this failure stems from the loss of connectivity between the silicon
(or its agglomerates), graphite, and PVDF binder because of the mechanical
stresses experienced during battery cycling. More importantly, we
reveal for the first time that the PVDF binder undergoes chemical
decomposition during the cycling of not only the composite but also
the Si-only or even graphite-only electrodes despite the excellent
battery performance of the latter. Through X-ray photoemission electron
microscopy and X-ray photoelectron spectroscopy techniques, LiF was
identified as the predominant decomposition product. We show that
the distribution of LiF in the electrodes due to the differences in
the interactions between PVDF and either Si or graphite could correlate
with the performance of the battery. This study shows that the most
suitable binder for the composite electrode is a polymer with a good
chemical interaction with both graphite and silicon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.