Fluorine-free "solvent-in-salt" sodium battery electrolytes: solvation structure and dynamics
Artikel i vetenskaplig tidskrift, 2024

The solvation structure, dynamics, and transport properties, as well as thermal and electrochemical stabilities of "solvent-in-salt" (SIS) electrolytes, also known as highly concentrated electrolytes, are far from fully understood. Furthermore, these special types of electrolytes are almost without exception based on fluorinated salts. In contrast, here we report on fluorine-free SIS electrolytes comprising ambient temperature liquid sodium bis(2-(2-ethoxyethoxy)ethyl)phosphate (NaDEEP) salt and tris(2-(2-ethoxyethoxy)ethyl)phosphate (TEOP) solvent, for which the ionic conductivities and ion diffusivities are altered profoundly as the salt concentration is increased. A careful molecular level analysis reveals a microstructure with a "solvent-rich" phase with almost an order of magnitude faster ion diffusion than in a "salt-rich" phase. Aggregated ionic structures in these SIS electrolytes lead to higher ionic conductivities alongside lower glass transition temperatures, <-80 degrees C, but also agreeable thermal stabilities, up to 270 degrees C, and improved anodic stabilities, possibly up to 7.8 V vs. Na/Na+ and at least >5 V vs. Na/Na+. Altogether, this provides a foundation for both better understanding and further development of fluorine-free SIS electrolytes for sodium batteries.

Författare

Yanqi Xu

Luleå tekniska universitet

Andrei Filippov

Luleå tekniska universitet

Sourav Bhowmick

Luleå tekniska universitet

Patrik Johansson

Chalmers, Fysik, Materialfysik

Faiz Ullah Shah

Luleå tekniska universitet

Energy Advances

27531457 (eISSN)

Vol. 3 3 564-573

Biomassbaserade fluorfria jonvätskeelektrolyter för möjliggörandet av hållbara batterier

Formas (2020-00969), 2021-01-01 -- 2024-12-31.

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Materialkemi

DOI

10.1039/d4ya00002a

Mer information

Senast uppdaterat

2024-04-02