Toyota develops new nano-sulfur cathode material to improve cr2032 button battery charging and discharging efficiency

Recently, a research team at Toyota Research Institute of North America (TRINA) has developed a new lithium-ion battery nano-sulfur cathode material that uses a truffle-like structure, including sulfur particles embedded in hollow carbon nanospheres and sealed flexible laminated (LBL) nanofilm carbon conductors.

TRINA has published a paper in the Royal Society of Chemistry (RSC) journal Energy and Environmental Science. In the paper, the researchers pointed out that the new nano-sulfur cathode material (65% final sulfur loading) can work under 2C high rate conditions (1C corresponds to 1 hour of full charge or discharge) and can complete more than 500 charge and discharge cycles, with a Coulomb efficiency (i.e., charge and discharge efficiency) of almost 100%.

During the entire chemical reaction process, since the laminated nanofilm carbon conductor can self-assemble, the formation of an orderly supramolecular structure for the surface characteristics of the nano-sulfur cathode material will be greatly affected. Any material with adhesion and capable of reacting with solvents (ionic or hydrogen bonds) can be converted into a multi-molecular layer structure by lamination. The above results suggest that this new nano-sulfur cathode material will be an ideal solution for other low-conductivity battery cathodes in the future.

The nano-sulfur cathode material can bring a theoretical capacity of up to 1672 mAh/g, which is very attractive for next-generation batteries. However, in practical applications, problems such as high resistance, low loading of active materials, and decomposition of polysulfides in the electrolyte during charge and discharge still pose considerable challenges, which can lead to reduced Coulombic efficiency, accelerated battery capacity loss, and self-discharge.

Previously, many research groups have been exploring the use of polymer electrolytes, nano-coatings and nano-membranes to prevent polysulfide decomposition to improve the performance of lithium-sulfur batteries. After many experiments, TRINA researchers found that although polymer-based electrolytes can be used to prevent polysulfide decomposition, their conductivity is significantly lower than that of ordinary liquid-based electrolytes, which makes it more difficult to achieve efficient discharge rates.

When polymers are used in composite materials or nano-coatings, the cycling characteristics of sulfur cathodes are improved. In addition, polymers can provide sulfur cathodes with an elastic framework to freely adjust the capacity between charge and discharge. At the same time, the new structure used by the TRINA research team in the nanosulfur cathode material of lithium-ion batteries can also inhibit the decomposition of intermediate polysulfides and reduce the generation of carbon conductors.

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