High‐Performant All‐Organic Aqueous Sodium‐Ion Batteries Enabled by PTCDA Electrodes and a Hybrid Na/Mg Electrolyte

Abstract

Aqueous sodium-ion batteries (ASIBs) are aspiring candidates for low environmental impact energy storage, especially when using organic electrodes.I nt his respect, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is apromising anode active material, but it suffers from extensive dissolution in conventional aqueous electrolytes.Asaremedy, we here present anovel aqueous electrolyte,whichinhibits the PTCDAdissolution and enables their use as all-organic ASIB anodes with high capacity retention and Coulombic efficiencies.F urthermore,t he electrolyte is based on two,h ence "hybrid", inexpensive and non-fluorinated Na/Mg-salts,i t displays favourable physico-chemical properties and an electrochemical stability window > 3V without resorting to the extreme salt concentrations of water-in-salt electrolytes.A ltogether,t his paves the wayf or ASIBs with both relatively high energy densities,i nexpensive total cell chemistries,l ong-term sustainability,a nd improved safety.

Superconcentrated NaFSA–KFSA Aqueous Electrolytes for 2 V-Class Dual-Ion Batteries

“…Not only anionic mixing but also cationic mixing decrease the melting point and increase the solubility − because the larger entropy increase from the solid mixtures to the liquid mixtures at the eutectic mixture makes the liquid phase more stable . In dual-cation electrolytes such as Na–K systems, both cations could be inserted into active materials, realizing a wide variety of positive and negative electrode configurations.…”