Highly Pseudocapacitive Storage Design Principles of Heteroatom-Doped Graphene Anode in Calcium-Ion Batteries

Pseudocapacitive storage of multivalent ions, especially Ca2+, in heteroatom-doped carbon nanomaterials is promising to achieve both high energy and power densities, but there is the lack of pseudocapacitive theories that enable rational design of the materials for calcium-ion batteries. Herein, the general design principles are established for the anode materials of the batteries via density functional theory calculations and experimental verifications of a series of heteroatom-doped graphene as an efficient pseudocapacitive anode. A novel descriptor & phi; is proposed to correlate the intrinsic properties of dopants with the pseudocapacitive storage properties of the carbon-based anode. The design principle and descriptor have the predictive ability to screen out the best dual-doped graphene anode with 10 times higher Ca2+ storage capability than that of sole-doped one, and exceed the current best Ca2+ storage anode materials.