Research that could make lithium ion batteries obsolete : Scientists at the University of Waterloo in Ontario
announced this week that they have made a breakthrough in lithium-sulfur battery technology that could increase an EVs
range by 3 times with the same weight and a lower cost. Essentially, sulfur would be a good battery cathode material
because, along with increasing energy density, it is abundant, light, and cheap. So finding materials that make the
battery's construction possible would be a breakthrough.
Lithium-sulfur technology is far from production, but if it lives up to expectations we could see a Model S with a
range of nearly 900 miles or a Nissan Leaf that could go 250 miles on a single charge, without a bigger battery.
The lithium–sulfur battery is receiving intense interest because its theoretical energy density exceeds that of
lithium-ion batteries at much lower cost, but practical applications are still hindered by capacity decay caused by the
polysulfide shuttle. Here we report a strategy to entrap polysulfides in the cathode that relies on a chemical process,
whereby a host—manganese dioxide nanosheets serve as the prototype—reacts with initially formed lithium polysulfides to
form surface-bound intermediates. These function as a redox shuttle to catenate and bind ‘higher’ polysulfides, and
convert them on reduction to insoluble lithium sulfide via disproportionation. The sulfur/manganese dioxide nanosheet
composite with 75?wt% sulfur exhibits a reversible capacity of 1,300?mA?h?g-1 at moderate rates and a fade rate over
2,000 cycles of 0.036%/cycle, among the best reported to date. We furthermore show that this mechanism extends to
graphene oxide and suggest it can be employed more widely.
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A highly efficient polysulfide mediator for lithium–sulfur batteries