LAUSR

Mesocarbon microbeads (MCMBs) have a unique structure consisting of graphite-like carbon crystallites covered by spherical surfaces. Their potential anode performance for sodium-ion batteries is investigated. The carbon crystallites in the MCMBs being prepared at 800 °C have a wider crystallites’ interlayer spacing (d = 0.347 nm) than graphite and are stacked by 5–6 graphene layers with an average crystal width of 3.18 nm. MCMBs present a reversible capacity of ~ 180 mAh g−1 and a coulombic efficiency of ~ 99% during 100 discharge/charge cycles. Their superior electrochemical performance is attributed to their unique structure. We propose that sodium is stored in MCMBs mainly by an intercalation mechanism. After sodium intercalation in carbon crystallites, the carbon atoms of graphene layers stack in an AABAA… type, and the sodium atoms exist between the layers of AA with a detected expanded interlayer spacing of 0.437 nm.