Swedish Researchers use a Graphene Sponge in Lithium Sulfur Batteries to achieve a Significantly Higher Energy Density

Swedish Researchers use a Graphene Sponge in Lithium Sulfur Batteries to achieve a Significantly Higher Energy Density

An all-electric future cannot be imagined without innovating new battery technologies. Lithium sulfur batteries offer five times more energy density than traditional lithium ion batteries. A promising new technology has been developed by researchers from Sweden’s Chalmers University of Technology which uses catholyte with help from a grapheme sponge.

 

The novel idea is to use a sponge-like porous aerogel made out of graphene oxide, which serves as a free standing electrolyte inside the battery cell to allow higher and better utilization of sulfur.

 

A conventional battery has four main parts: first includes two supporting electrodes coated by an active substance called as a cathode and an anode. The electrolyte between both the electrodes is generally a liquid which allows transfer of ions back and forth. The fourth part is a separator acting as a physical barrier which prevents any contact between the two electrodes to allow transfer of ions.

 

The team of researchers experimented by combining an electrolyte and a cathode into one single liquid called ‘catholyte’. Much weight in a battery can be saved by the new concept which offers better power capabilities and a significantly faster charging. The application of the new graphene aerogel has proven a viable and promising option.

 

The researchers inserted a thin layer of graphene aerogel in a standard coil cell battery. The lead researcher of the study from the Chalmer’s Department of physics, Carmen Cavallo said that they took the long thin cylindrical aerogel and sliced them into a slice like a salami and then they compressed it to accommodate in a battery. A sulfur rich solution then added to the battery and the porous aerogel soaks up the solution like a sponge.

 

Carmen Cavallo said that the key element of the graphene aerogel is its porous structure which is capable of soaking large amounts of catholyte giving a high sulfur loading to make the concept viable. The semi liquid catholyte is the most essential part of the technology as it allows for sulfur to cycle circularly without any losses. As it’s already dissolved in the catholyte solution, there is no loss through dissolution.

 

The problem with the current lithium sulfur batteries is the instability and the low cycle life. The degeneration rate of current versions is fat which makes for a limited life span with low cycle numbers. The new prototype developed by the Chalmers team has proven a capacity retention of 85% after 350 cycles.

 

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