•The electronic structures of Pillar[5]quinone (P5Q) accepting electrons and binding lithium atoms.•The microstructural evolution of P5Q as cathode active materials for LIBs during charging and discharging processes.•The relationship between structural stability and electrochemical performance of Pillar[n]quinones.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 M06-2X/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 P5Qn− anions can minimize the repulsive interactions as far as possible. The macrocyclic skeletons in P5QLin 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.Download high-res image (123KB)Download full-size image

The applicability of a novel macrocyclic multi-carbonyl compound, pillar[4]quinone (P4Q), as the cathode active material for lithium-ion batteries (LIBs) was assessed theoretically. The molecular geometry, electronic structure, Li-binding thermodynamic properties, and the redox potential of P4Q were obtained using density functional theory (DFT) at the M06-2X/6-31G(d,p) level of theory. The results of the calculations indicated that P4Q interacts with Li atoms via three binding modes: Li–O ionic bonding, O–Li···O bridge bonding, and Li···phenyl noncovalent interactions. Calculations also indicated that, during the LIB discharging process, P4Q could yield a specific capacity of 446 mAh g−1 through the utilization of its many carbonyl groups. Compared with pillar[5]quinone and pillar[6]quinone, the redox potential of P4Q is enhanced by its high structural stability as well as the effect of the solvent. These results should provide the theoretical foundations for the design, synthesis, and application of novel macrocyclic carbonyl compounds as electrode materials in LIBs in the future.

DFT calculations were reported for calix[4]arene derivatives [i.e., formylaminocalix[4]arene (1) and formylaminocalix[4]bis-crown-3 (2)] binding cations M+ (Li+, Na+, and K+) and anions X- (F-, Cl-, and Br-) simultaneously. The B3LYP function together with the LANL2DZp basis set was used in order to obtain insights into the factors determining the nature of the interactions of these compounds with X- and M+. Based on the molecular electrostatic potential (MEP) analysis, the result complexes M+X-/H (H = 1, 2) were investigated. For all the complex structures, the most pronounced changes in geometric parameters upon interaction were observed in the host segment compared with the free receptors. Two main types of driving force, N-H∙∙∙X- hydrogen bonds and electrostatic interactions between M+ and oxygen atoms, were confirmed. The recognition trends for 1 and 2 toward M+X- followed the same order: M+F- > M+Cl- > M+Br- (M+ is same to each other) and Li+X- > Na+X- > K+X- (X- is same to each other). The binding energy, enthalpy change, Gibbs free energy change, and entropy change of complexation formation have been studied by the calculated thermodynamic data. In all cases, the inclusion energy changes with 2 were more negative than those with 1, correlating with the flexible space available by the two crown ether moieties in 2. The calculated results of the model system have been reported and should be useful to the experimental research in this field.