Boron-, nitrogen-, aluminum-, and phosphorus-doped graphite electrodes for non-lithium ion batteries

Abstract

Intercalation of Li+, Na+, K+, Mg2+, Ca2+, Zn2+, and Al3+ ions into B-, N-, Al-, and P-doped graphite has been studied using density functional theory calculations. While the intercalation of Li+, K+, and Ca2+ ions into graphite is thermodynamically favorable, that of Na+, Mg2+, Zn2+, and Al3+ ions into graphite is unfavorable. When doped in the form of graphitic structure, B, Al, and P dopants significantly stabilize the ion-intercalated graphite compounds. As a result, Na+ ions that are unable to intercalate into graphite can intercalate into B-, Al-, and P-doped graphite. The electron transfer from B, Al, and P dopants to host C atoms reinforces the ion-graphene electrostatic interaction, enhancing the thermodynamic driving force for ion intercalation. The catalytic activity of the dopant to promote the ion intercalation increases in the order of N < B < P < Al, which is associated with the electronegativity of the dopant.