DOPANT-FREE MAIN GROUP ELEMENTS SUPPORTED COVALENT ORGANIC–INORGANIC HYBRID CONDUCTING POLYMER FOR SODIUM-ION BATTERY APPLICATION

Abstract

Organic–inorganic hybrid polymeric materials have shown potential applications in various fields. An approach to prepare a new class of a covalent organic–inorganic hybrid polymer (COIHP-1) using tris(2,3,6,7,10,11-hexahydroxytriphenylene) and inorganic heterocycle (hexachlorophosphazene) is developed. The design of COIHP-1 with porous nature has been an important goal as it can fulfill the demands of next-generation batteries and other electrochemical devices. COIHP-1 shows a high electrical conductivity of 9.52 × 10–3 S/cm. For the first time, COIHP-1 is employed as an anode material with maximum capacity in Na+ batteries, and it was characterized by various spectroscopic studies. It delivers a reversible capacity of 310 mAh g–1 at a current density of 0.035 A g–1, retains 65% of initial capacity after 500 cycles, and preserves the mesoporous nature even after prolonged cycling as proved by the post transmission electron microscopy (TEM) analysis. Moreover, COIHP-1 shows an excellent rate capability: it delivers 90 mAh g–1 even at a high current density of 3 A g–1. The enhanced Na+ storage capability, cycling stability, and rate capability are due to the mesoporous scaffold, which offers reversible accommodation for the ions. Mainly, the Na+ storage capability of COIHP-1 arises because of its polymeric −P═N− framework layer, which also provides hosting sites for the ions in the π-bond or lone pair of N. This work opens a door for developing a new kind of hybrid polymeric electrode material for rechargeable Na+ batteries.