Effect of Anion Receptor Additives on Electrochemical Performance of Lithium-Ion Batteries

Four boron-based anion receptors were investigated as electrolyte additives for lithium-ion batteries. The electrochemical performance of lithium-ion cells was found to strongly depend on the structure of the anion receptor added to the electrolyte. The capacity retention of the lithium-ion cell was slightly improved by adding 0.07 M bis(1,1,1,3,3,3-hexafluoroisopropyl)pentafluorophenylboronate additive, whereas the addition of 2,5-bis(trifluoromethylphenyl)tetrafluoro-1,3,2-benzodioxaborole dramatically deteriorated the electrochemical performance. The addition of a certain type of anion receptor can promote the electrochemical decomposition of the electrolyte, resulting in high interfacial impedance and accelerated capacity fading of lithium-ion cells. Ab initio calculations showed that the electrochemical performance of anion receptors had good correlation to the degree of localization of the lowest unoccupied molecular orbital at the boron center of anion receptors, which can potentially be used in the search for new anion receptors for lithium-ion batteries.