Computational electrochemistry of Pillar[5]quinone cathode material for lithium-ion batteries

Multi-carbonyl macrocyclic compounds have recently attracted much attention due to their high performance relative to some short chain carbonyl compounds as the cathode active constituents for lithium ion batteries (LIBs). However, little is known about the evolution mechanism of their electrochemical properties during charging and discharging processes. In this paper, the application of density functional calculations at the MO6-2X/6-31G(d,p) level of theory is presented to study systematically the electrochemical properties of pillar[5]quinone (P5Q) as a cathode active material for LIBs. The optimized structures of P5Q accepting different number of electrons and binding different number of lithium atoms are obtained, respectively. The geometry structure, thermodynamics property, electronic structural property, solvent effect and redox potential are discussed in detail. The uneven-distribution of extra electrons in several P5Q(n-) anions can minimize the repulsive interactions as far as possible. The macrocyclic skeletons in P5QLi(n) structures are distorted to different extents by the binding interactions between Li atoms and P5Q More than eight intercalated lithium atoms into per P5Q molecule are confirmed in this work, indicating a high utilization ratio of carbonyl groups of P5Q as a cathode material. Compared with pillar [4]quinone and pillar[6]quinone, P5Q is predicted to have better cycling performance due to its higher structural stability. (C) 2017 Elsevier B.V. All rights reserved.