Rational design of a CN/CB p-n heterostructure as a promising anode material in Li-ion batteries.

It is urgent to develop high-performance anode materials for lithium-ion batteries. In this work, a CN/CB p-n heterostructure was systematically investigated by first-principles calculations. The bonding strength of Li in CN is relatively low (-0.53 eV), whereas the CN/CB heterostructure (-1.64 eV to -2.84 eV) can greatly improve the bonding strength without compromising the Li migration capability. The good bonding strength and Li mobility in the CN/CB heterostructure are mainly caused by the synergy effect and internal electric field of the p-n heterostructure. Moreover, the electronic structures indicate that the CN/CB heterostructure has good conductivity with a tiny bandgap of 0.09 eV. Compared to pristine CN, the stiffness of the CN/CB heterostructure improved significantly (549.35 N m). Besides, the CN/CB heterostructure presents a high lithium-ion storage capacity (986.61 mA h g). The ultrahigh stiffness, good conductivities of electrons and ions, high bonding strength of Li, and high capacity show that the CN/CB heterostructure is a prospective anode material for lithium-ion batteries.