All‐Organic Rechargeable Battery with Reversibility Supported by “Water‐in‐Salt” Electrolyte

Abstract

Rechargeable batteries with organic electrodes are preferred to those with transition-metal-containing electrodes for their environmental friendliness, and resource availability, but all such batteries reported to date are based on organic electrolytes, which raise concerns of safety and performance. Here an aqueous-electrolyte all-organic rechargeable battery is reported, with a maximum operating voltage of 2.1 V, in which polytriphenylamine (PTPAn) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA)-derived polyimide (PNTCDA) serve as cathode and anode material, respectively. A key feature of the design is use of a "water-in-salt" electrolyte to bind "free" water; this impedes the side reaction of water oxidation, thereby enabling excellent reversibility in aqueous solution. The battery can deliver a maximum energy density of 52.8 Wh kg , which is close to most of the all-organic batteries with organic electrolytes. The battery exhibits a supercapacitor-like high power of 32 000 W kg and a long cycle life (700 cycles with capacity retention of 85 %), due to the kinetics not being limited by ion diffusion at either electrode.

Sustainable Energy Storage: Recent Trends and Developments toward Fully Organic Batteries

“…Dong et al. used an ethylene‐linked NDI polymer to build an all‐organic cell with a polytriphenylamine counter electrode and a highly concentrated (21 m ) aqueous lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte . The resulting working voltage strongly decreased during the discharge, but the capacity loss was only 15 % over 700 cycles (Figure , right).…”

“… Performance of a poly(perylene diimide)/poly(triphenylamine) cell, in particular voltage profiles (top left) and capacities at different charge/discharge currents (top right), revealing a good rate capability of the system, as well as the capacity development over 2000 cycles (bottom), showing a good long‐term stability. (Reprinted with permission of the Royal Society of Chemistry, Copyright 2018) …”

“…They allow the construction of cells that feature very stable capacities over several hundreds or even thousands of cycles . Furthermore, they were successfully applied in all‐organic cells, in particular in combination with polytriphenylamines . The interesting approach of combining diimides with quinone units in co‐polymers showed, however, no significant improvement.…”

Recent Progress of Rechargeable Batteries Using Mild Aqueous Electrolytes

“…The battery exerts a supercapacitor‐like high power density and 50 000 cycles long life span when operated between 0 and 1.6 V. The application of organic electrodes in aqueous electrolytes is also restricted by the narrow electrochemical stability window of water. Recently, by introducing the “water‐in‐salt” electrolyte, a full aqueous battery with all‐organic electrodes (polyimide as anode, p‐dopable polytriphenylamine (PTPAn) as cathode) was proposed . The full battery can exert a maximum 52.8 Wh kg −1 energy density that is comparable to the aqueous batteries for large‐scale energy storage.…”

Advances in electrode materials for Li-based rechargeable batteries

“…186 An aqueous electrolyte containing lithium bis(triuoromethanesulfonyl)imide (LiTFSI) with a concentration of 21 molarity allows a high redox potential of polytriphenylamine cathode (Fig. 15a), and a low negative potential of 1,4,5,8-naphthalenetetracarboxylic dianhydride-derived polyimide anode (Fig.…”