Probing Electrolyte Structure at Interfaces: An Example of the Power of Variable Temperature and Pressure Operando MAS NMR

Scientific Achievement

We have developed a robust method to analyze battery systems under finely-controlled environments of specified composition, temperature, and pressure to reveal the interactions of electrolytes with electrode surfaces.

Significance and Impact

Complex surface phenomena that block the ion transport required for electrochemical cycling are known to hinder electrochemical cell performance. These interactions are poorly understood, necessitating detailed studies of the interactions of electrolytes with the electrode surfaces.

Research Details

  • Sealed NMR rotors enable the observation of chemical species at elevated temperatures and pressures
  • Mg-based batteries show promise as a next-generation technology, but the thermal decomposition of electrolytes on the electrode surface has been a relatively unexplored area
  • Operando NMR demonstrated that neat diglyme (G2) decomposes to methoxy species that adsorb onto the MgO passivation layer
  • G2 represents the major MgO-adsorbed species for electrolyte 0.1 M Mg(TFSI)2 in G2, but 1.0 M electrolytes show G2-solvated Mg-TFSI contact ion pairs on the surface which have undergone a desolvation process

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DOI: 10.1021/acs.accounts.9b00557

DOI: 10.1021/acsami.9b11888

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