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

Abstract

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.

Electrolytes and Interphases in Li-Ion Batteries and Beyond

“…111 Using ab initio calculations Amine and co-workers systematically studied the structure−property relationships for a series of anion receptors based on borates, boroles, boranes, and boronates (Table 10), and concluded that there was an obvious correlation between the LUMO localization and electrochemical performance. 112,113 It is obvious from the table that the general ability for anion receptors to compete with PF 5 in coordinating F − increases with number of F on the delocalized substituents and decreases with the oxygens connected to boron center.…”

High Performance Lithium-Ion Batteries Using Fluorinated Compounds

“…Therefore, the addition of a small amount of anion receptor to the nonaqueous electrolyte can improve both the rate capabilities [28] and the capacity retention [28][29][30][31] of lithium-ion cells.…”

“…Based on the results of the DFT calculations, a group of highly fluorinated boron-based anion receptors was selected for detailed electrochemical characterization. It turned out that the fluorine affinity of the anion receptors has a strong effect, but not monotonic, on the electrochemical performance of lithium-ion cells [30]. Some strong anion receptors even lead to a decrease in reversible capacity of the cells, which was attributed to the difficulty in controlling the amount of anion receptor in the electrolyte; excess strong anion receptors can also promote the decomposition of LiPF 6 into LiF and PF 5 .…”

Additives for Functional Electrolytes of Li-Ion Batteries

“…Furthermore, anion receptors have been known to stabilize the metallic lithium anode in lithium metal batteries [31,173]. They have also been reported to increase the thermal stability of the SEI layer [50], increase the power capability of batteries [24], and improve the overall performance of the cell [104]. Some anion receptors can also act as redox shuttles because of their reversible redox reaction at suitable potential ranges [25,137].…”