sp/sp Hybridized Carbon as an Anode with Extra Li-Ion Storage Capacity: Construction and Origin.

Doping in carbon anodes can introduce active sites, usually leading to extra capacity in Li-ion batteries (LIBs), but the underlying reasons have not been uncovered deeply. Herein, the dodecahedral carbon framework (N-DF) with a low nitrogen content (3.06 wt %) is fabricated as the anode material for LIBs, which shows an extra value of 298 mA h g during 250 cycles at 0.1 A g. Various characterizations and theoretical calculations demonstrate that the essence of the extra capacity mainly stems from non-coplanar sp/sp hybridized orbital controlling non-Euclidean geometrical structure, which acts as new Li-ion active sites toward the excess Li adsorption. The electrochemical kinetics and transmission electron microscope further reveal that the positive and negative curvature architectures not only provide supernumerary Li storage sites on the surface but also hold an enhanced (002) spacing for fast Li transport. The sp/sp hybridized orbital design concept will help to develop advanced electrode materials.