Cathode material boosts Li-S battery performance

While lithium-sulphur batteries provide a potential replacement for Li-ion technology, issues with the chemistry mean the battery’s capacity declines over multiple charging cycles as a result of the ‘shuttle effect’. Looking to overcome this problem, researchers are developing cathode materials that can either confine or encapsulate polysulphides.

A team from Helmholtz-Zentrum Berlin, headed by Professor Yan Lu, has fabricated a cathode material that uses Ti4O7 molecules arranged on a porous spherical surface to confine sulphur. According to the team, these porous nanoparticles bind polysulphides more strongly than TiO2 based nanoparticles. “We have developed a special fabrication process to generate this complex, three-dimensionally interconnected pore structure”, said Prof Lu.

Compared with other cathode materials made of titanium oxides, the Ti4O7 nanosphere matrix possesses an extremely large surface area and a specific capacity of 1219mAh/g at 0.1C, where 1C=1675mA/g. The specific capacity is said to decline by 0.094% per charge/discharge cycle. Meanwhile, the specific capacity of cathode materials made of TiO2 nanoparticles is 683mAh/g.