Korean researchers at the Center for Self-assembly and Complexity,
Institute for Basic Science (IBS), Department of Chemistry and Division
of Advanced Materials Science at Pohang University, have created a new
LIB made from a porous solid which greatly improves its performance as
well as reducing the risks due to overheating.
2002 there have been over 40 recalls in the US alone due to fire or
explosion risk from LIBs used in consumer electronic devices. These
types of batteries, in all of their different lithium-anode
combinations, continue to be an essential part of modern consumer
electronics despite their poor track record at high temperatures.
Korean team tried a totally new approach in making the batteries.
According to Dr. Kimoon Kim at IBS, "we have already investigated high
and highly anisotropic [directionally dependent] proton conducting
behaviors in porous CB for fuel cell electrolytes. It is possible for
this lithium ion conduction following porous CB to be safer than
existing solid lithium electrolyte -based organic-molecular
porous-materials utilizing the simple soaking method." Current LIB
technology relies on intercalated lithium which functions well, but due
to ever increasing demands from electronic devices to be lighter and
more powerful, investigation of novel electrolytes is necessary in
new battery is built from pumpkin-shaped molecules called
cucurbituril (CB) which are organized in a honeycomb-like
structure. The molecules have an incredibly thin 1D-channel, only
averaging 7.5 Å [a single lithium ion is 0.76 Å, or .76 x 10-10 m] that
runs through them. The physical structure of the porous CB enables
the lithium ions to battery to diffuse more freely than in conventional
LIBs and exist without the separators found in other batteries.
tests, the porous CB solid electrolytes showed impressive lithium
ion conductivity. To compare this to existing battery electrolytes, the
team used a measurement of the lithium transference number (tLi+) which
was recorded at 0.7-0.8 compared to 0.2-0.5 of existing electrolytes.
They also subjected the batteries to extreme temperatures of up to 373 K
(99.85° C), well above the 80° C typical upper temperature window for
exiting LIBs. In the tests, the batteries were cycled at temperatures
between 298 K and 373 K ( 24.85° C and 99.85° C) for a duration of four
days and after each cycle the results showed no thermal runaway and
hardly any change in conductivity.
conventional liquid electrolytes can incorporate in a porous CB
framework and converted to safer solid lithium electrolytes.
Additionally, electrolyte usage is not limited to use only in LIBs, but a
lithium air battery potentially feasible. What makes this new technique
most exciting is that it is a new method of preparing a solid lithium
electrolyte which starts as a liquid but no post-synthetic modification
or chemical treatment is needed.