Correlating Li-Ion Solvation Structures and Electrode Potential Temperature Coefficients.

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Temperature coefficients (TCs) of electrode potentials are vital for understanding lithium-ion battery thermal safety and material phase transitions.
• The fundamental significance of single electrode potential TCs, particularly for lithium (Li)/Li⁺ electrodes, remains underexplored.

Purpose of the Study:

• To investigate the contribution of Li-ion desolvation entropy to Li/Li⁺ electrode potential TCs.
• To establish correlations between Li/Li⁺ electrode potential TCs and Li-ion solvation structures in various electrolytes.
• To demonstrate the utility of Li/Li⁺ electrode potential TCs as a screening tool for new battery electrolytes.

Main Methods:

• Comparative analysis of Li/Li⁺ electrode potential TCs across diverse electrolyte formulations with varying solvent, anion, and salt concentrations.
• Utilizing *ab initio* molecular dynamics simulations to verify established correlations between TCs and Li-ion solvation structures.

Main Results:

• The Li-ion desolvation process during Li deposition/intercalation is shown to significantly contribute to Li/Li⁺ electrode potential TCs due to substantial entropy changes.
• Direct correlations were established between measured electrode potential TCs and the specific Li-ion solvation structures within different electrolytes.
• The study confirms that TCs provide valuable insights into Li-ion solvation environments.

Conclusions:

• Li/Li⁺ electrode potential TCs are significantly influenced by Li-ion desolvation entropy.
• Electrode potential TCs serve as a valuable indicator of Li-ion solvation environments.
• Measurements of Li/Li⁺ electrode potential TCs can be effectively employed as a screening tool for designing advanced electrolytes for next-generation lithium-ion and lithium metal batteries.