Ab initio study of mechanical strength of solid polymer electrolyte (PEO)5LiClO4

Abstract

Mechanical strength is one of the significant properties of any solid polymer electrolyte of electrochemical devices, therefore; the ab initio study based on density functional theory is performed, and the bond strength of Poly ethylene oxide (PEO)5 polymer without and with Lithium Perchlorate (LiClO4) is investigated. The central oxygen atom of PEO is displaced till to respective bond is broken along X, Y, and Z directions, respectively. The same is simulated in the presence of LiClO4 and the minimum bond breaking energy which is also called the mechanical strength is calculated along three directions. Higher energy is required in compression of (PEO)5 along x and y axes than expansion, and vice versa along z axis. The same is observed for (PEO)5-LiClO4 polymer electrolyte along x and y axes, along z direction; the energy required is nearly same for compression/expansion. Due to this energy, crystalline nature of a polymer is reduced and amorphous nature is increased. In DOS analysis, the forbidden energy gap of (PEO)5-LiClO4 is reduced by 1.0 eV than (PEO)5; it causes to increase the lithium cation concentration and the ionic conductivity.