Low-Cost and Sustainable Aqueous Lithium-Ion Batteries by All-Organic PTCDI Anodes

Abstract

Electrolyte engineering has been key to the advancement of aqueous lithium-ion batteries (ALIBs), for example, the introduction of water-in-salt electrolytes (WiSEs) has enabled ALIBs to cycle well and to operate at potentials far beyond the electrochemical stability window of water. WiSEs are, however, intrinsically based on high concentrations of salt(s) which furthermore often are expensive and fluorinated, and therefore defeats the aim of ALIBs being low-cost and sustainable. Strategies to circumvent this issue have been to add co-solvents and/or diluents to decrease the overall electrolyte concentration or customize the anion and salt concentration to each battery chemistry. The clean and green ethos of ALIBs can be enhanced by using organic active materials (AMs), but these are unfortunately often water soluble and therefore requires an electrolyte designed to mitigate dissolution/electrode de-attachment.Herein, we for the first time implement perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) as the anode AM for ALIBs. We demonstrate that by appropriate aqueous electrolyte selection we can truly mitigate electrode de-attachment, leading to excellent properties in terms of capacity, rate capability, cycling stability, and Coulombic efficiency. All things considered, this endeavour intends to further reduce the kWh/€ and thereby reinforcing the feasibility of more cost-effective large-scale battery energy storage solutions Fig 1. Long term galvanostatic cycling of an all-organic PTCDI electrode in a PTCDI/low conc. aqueous el./LFP cell set-up. Inset shows the chemical structure of PTCDI and the corresponding charge/discharge voltage curves. Figure 1