Researchers have developed a molecularly engineered interlayer that tackles one of the biggest barriers to commercial lithium-sulfur batteries, allowing the cells to retain capacity over 1,000 charge-discharge cycles while delivering high energy density.
The team, led by researchers at Tohoku University and collaborating institutions, created a covalent organic framework (COF)-graphene interface that prevents the movement of lithium polysulfides inside the battery. The unwanted migration, known as the polysulfide shuttle effect, has long reduced the lifespan and efficiency of lithium-sulfur batteries.
Lithium-sulfur batteries are considered a promising alternative to today’s lithium-ion technology because sulfur is abundant, inexpensive, and capable of storing much more energy. However, dissolved lithium polysulfides formed during charging and discharging can migrate between the battery’s electrodes, triggering side reactions and causing rapid capacity loss.
Instead of relying on a physical barrier, the researchers designed an interlayer that chemically captures polysulfides while also helping them continue participating in the battery’s electrochemical reactions.
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