The document summarizes research into developing new solid polymer electrolytes (SPEs) for lithium-ion batteries. SPEs offer safety advantages over liquid electrolytes but have lower conductivity at room temperature. The researchers synthesized a new lithium salt called 4mer-O-Li and combined it with polyoctahedral silsesquioxane-ethylene glycol (POSS-PEG8) to create electrolytes. Testing found the conductivity of the 4mer-O-Li/POSS-PEG8 electrolyte was 1.5 x 10-5 S/cm at 60°C and 4.04 x 10-6 S/cm at 25°C. However, the conductivity at room temperature is still too low for

1. The Blends of POSS-PEG and Multi-ionic Janus Lithium Salts as Electrolytes for Lithium-Ion Batteries
Ramya Mantravadi, Cody Lee Goldberg, Parameswara Rao Chinnam and Stephanie L. Wunder
Department of Chemistry, Temple University, Philadelphia, PA 19122
ABSTRACT:
The motivation for the development of solid polymer
electrolytes (SPEs) arises from its safety advantages over
liquid electrolytes. In particular SPEs are non-flammable and
avoid the problem of electrolyte leakage, both of which can
result in fires/explosions. However, SPEs have lower
conductivities at room temperature (RT) compared to those of
liquid electrolytes, so there is a need to develop SPEs with
improved RT conductivity.
In our current work, we have synthesized a new, novel lithium
salt 4mer-O-Li and prepared electrolytes from mixtures of this
salt with another nanomaterial, namely polyoctahedral
silsesquioxane-ethylene glycol (POSS-PEG8). The structures of
these nanomaterials are shown in Figure 1. Temperature
dependent conductivity was measured for these
nanomaterials and compared with the conductivities of POSS-
PEG8 and LiBF4. The ionic conductivity of 4mer-O-Li /POSS-
PEG8 is 1.5 x 10-5 S/cm at 60 0C and 4.04 x 10-6 S/cm at 25 0C.
Fig. 1. Structures of POSS-PEG8, 4mer-O-Li
Fig. 4. DSC scans of POSS-PEG8/ 4mer-O-Li
Compositions at different O/Li ratios
Fig. 6. Conductivity data of 4mer-O-Li in POSS-
PEG8 at various EO:Li ratios. For comparison,
LiBF4 in POSS-PEG8 is also shown.
CONCLUSIONS:
 With an increase in 4mer-O-Li content, Tg
doesn’t increase much but ΔHm is
suppressed.
 In 4mer-O-Li, Li+ dissociation is low
compared with LiBF4.
 Viscosity of 4merLi >> LiBF4
 The ionic conductivity in 4mer-O-Li results
from more Li+ ion transport because of
large anion compared with LiBF4
 The ionic conductivity at RT is low for
practical battery applications
 In order to improve conductivity more
dissociation of Li+ is required -need to
convert Si-O-Li to Si-O-BF3Li
ACKNOWLEDGEMENTS:
DMR-1207221 for the support
Fig. 3. TEM images of 4mer-O-Li DMSO solvate
32.245
8.885
11.812
4.5052.727
1.5
0
5
10
15
20
25
30
35
5 10 15 20 25 30 35 40
Viscosity(cP)
Temperature (oC)
1.5 M 4mer
1.0 M 4mer
0.5 M 4mer
1.5 M LiBF4
1.0 M LiBF4
0.5 M LiBF4
Fig. 5. Viscosity of 4mer-O-Li and LiBF4 in
EC/DEC/DMC (1:1:1 by mass).
Fig. 2. Thermal ellipsoid plot of 4mer-O-Li DMSO solvate