Lithium attachment to C60 and nitrogen- and boron-doped C60: a mechanistic study

TL;DR

This study uses ab initio calculations to analyze lithium attachment to C60 and doped C60, revealing how doping affects electronic structure and voltage, with implications for battery anode design.

Contribution

It provides a detailed mechanistic understanding of lithium attachment and doping effects on C60-based materials using ab initio methods.

Findings

Doping alters electronic structure and voltage profiles.

Single atom doping does not significantly modulate voltage beyond initial lithiation.

GGA and hybrid functionals show semi-quantitative agreement but qualitative differences.

Abstract

Fullerene-based materials including C60 and doped C60 have previously been proposed as anodes for lithium ion batteries. It was also shown earlier that n- and p-doping of small molecules can substantially increase voltages and specific capacities. Here, we study ab initio the attachment of multiple lithium atoms to C60, nitrogen-doped C60 (n-type), and boron doped C60 (p-type). We relate the observed attachment energies (which determine the voltage) to changes in the electronic structure induced by Li attachment and by doping. We compare results with a GGA functional and a hybrid functional and show that while they agree semi-quantitatively with respect to the expected voltages, there are qualitative differences in the electronic structure. We show that, contrary to small molecules, single atom n- and p-doping will not lead to practically useful modulation of the voltage-capacity curve beyond the initial stages of lithiation.