A Cryogenic Milling Method to Fabricate Nanostructured Anodes

Cryogenic milling was demonstrated as a new and facile method to fabricate nanostructured battery electrode materials. SnSb anode material with 1.2 wt% graphite was selected as a model system to demonstrate the feasibility and benefits of this method. Ball milling at a cryogenic temperature can suppress cold welding, exfoliate bulk graphite powder into nanoplatelets, and evenly disperse them between the grains. Aberration-corrected scanning transmission electron microscopy and post-cycling scanning electron microscopy showed refined grain sizes and well-dispersed carbon nanoplatelets, which can stabilize the nanostructure and alleviate volume expansion and cracking upon cycling. The cryomilled SnSb-C composite anode showed a reversible volumetric capacity of 1842 Ah/L, average coulombic efficiency of 99.6 ± 0.3%, and capacity retention of 90% over 100 cycles. The cryomilled sample showed improved electrochemical performance compared to the conventional ball milled specimen. This new method of cryogenic milling can produce various other high-performance nanostructured electrode materials.