S. Himmelstein | July 05, 2022

Lithium-ion batteries hold great promise for powering electric vehicles and portable electronics — until extremely cold temperatures are encountered. Poor battery performance under subzero temperature conditions is evident as slow charging for most applications and reduced range and energy transfer in vehicular use. Past research has confirmed that the flat orientation of graphite in the anode is responsible for the drop in the energy storage capacity of these batteries under cold conditions, efforts to modify the surface structure of a carbon-based material to improve the anode’s charge transfer process.

Researchers from Tianjin University (China), Karlsruhe Institute of Technology (Germany), Beijing Jiaotong University (China) and the Chinese Academy of Sciences engineered a new anode design by heating a cobalt-containing zeolite imidazolate framework material to form 12-sided carbon nanospheres. These structures sport bumpy surfaces that offer excellent electrical charge transfer abilities, making them suitable for inclusion as an anode material in a coin-shaped battery with a lithium-metal cathode.

Schematic illustration of the synthesis process of the dodecahedral carbon framework. Source: ACS Cent. Sci. 2022/doi.org/10.1021/acscentsci.2c00411Schematic illustration of the synthesis process of the dodecahedral carbon framework. Source: ACS Cent. Sci. 2022/doi.org/10.1021/acscentsci.2c00411

The anode demonstrated stable charging and discharging at temperatures from 77° F to -4° F and maintained 85.9% of the room temperature energy storage capacity just below freezing. In comparison, lithium-ion batteries assembled with other carbon-based anodes, including graphite and carbon nanotubes, held almost no charge at freezing temperatures. When the air temperature was lowered to -31° F, the bumpy anode was still rechargeable, and during discharge released nearly 100% of the charge put into the battery.

The bumpy nanosphere material described in ACS Central Science could expand scope for using lithium-ion batteries at extremely low temperatures.