Perylene-Tetracarboxylic Diimide (PTCDI) Organic Cathode for Nonflammable K-Ion Batteries

Abstract

3,4,9,10-Perylene-tetracarboxylic diimide (PTCDI) is an advanced and low-cost organic small-molecule electrode with 2-electron reaction (theoretical specific capacity CT=137 mAh g-1) in potassium ion batteries (PIBs). However, K metal anode is exceedingly active and risky. In order to eliminate security risks of K-metal batteries, triethyl phosphate (TEP) as a kind of cheap and nonflammable electrolyte is used for an extinguisher in K-ion batteries. In this paper, using 2 mol L-1 potassium bis(fluoromethanesulfonyl)imide (KFSI)/TEP electrolyte, PTCDI can show a highly stable cycle of 134 mAh g-1 after 100 cycles at 50 mA g-1 with a capacity retention radio of 98% (1.5-3.5 V). At a large current density of 500 mA g-1 (3.65 C), PTCDI also can deliver the capacity of 60 mAh g-1. And the safety of K-metalIIPTCDI PIBs is demonstrated by the fact that the used separator does not produce an open flame after ignition. These results of PTCDI can represent the advanced properties of organic cathode using TEP in PIBs.