Scientists at the University of Waterloo, Canada, have created a new lithium battery that can store and deliver more than three time the power of conventional batteries. The study demonstrated robust electrochemical performance of a lithium-sulphur battery.
Sulphur is cheaper than many other materials currently used in lithium batteries. It has always showed great promise as the ideal material for a safe, low cost, long lasting rechargeable battery, needed for energy storage and transportation in a low carbon emission energy economy.
During the research, the most difficult part was to enable a reversible electrochemical reaction at high current rates, as the electrically-active sulphur needs to remain in an intimate contact with a conductor, such as carbon. Using a nanoscale method, the team assembled a structure of 6.5 nanometre thick carbon rods separated by some empty channels. To fill the void, heated and melted sulphur was used.
Carbon microfibres spanning the empty channels kept the voids open and prevented collapse of the structure. All the spaces were uniformly filled with sulphur, exposing an enormous surface area of the active element to carbon. This composite material can supply up to nearly 80 percent of the theoretical capacity of sulphur, which is three times the energy density of lithium transition metal oxide cathodes, at reasonable rates with good cycling stability.
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