Band-Gap Tuned Dilithium Terephthalate from Environmentally Hazardous Material for Sustainable Lithium Storage Systems with DFT Modelling

Abstract

In the fast-developing world, people must migrate to hybrid electric vehicles with a high energy density of lithium-ion batteries to reduce air and sound pollution primarily. Herein, acid hydrolysis is used to depolymerize vest post-consumer polyethylene terephthalate (PET) bottles, resulting in pure terephthalic acid (TPA). It was used in an acid-base reaction to produce the dilithium terephthalate (Li2TP). By using H-1, (CNMR)-C-13, and FTIR spectroscopy, the obtained TPA and its salt Li2TP are thoroughly studied. In terms of electrochemical properties, TPA has a restricted reversible capacity of 102 mAh g(-1) with dramatic fading and a coulombic efficiency of 98.2 % over the 50th cycle at 1 C. The resulting Li2TP, displays a three-fold higher reversible capacity of 295 mAh g(-1), with 99.8 % capacity retention and stable cycling at a similar rate over the 50th cycle. Moreover, computationally found that the charged state of Li2TP has a highly unstable structure due to a high steric hindrance and strong similar charge repulsion between lithium ions and it shows bandgap energy 0.2318 eV with four ionic bonds (1.7748 angstrom) and two new metallic bonds (3.2114 angstrom), which is 22 times smaller than TPA. Furthermore, Li2TP has a lower dielectric constant/loss and higher dipole movement than TPA, with values of 1.32E+04/1.24E+03, and 5.93E+03 respectively, and it improves Li-ion transportation of Li2TP in organic electrolytes.