화학공학소재연구정보센터
Journal of Power Sources, Vol.338, 103-107, 2017
Influence of the structure of the anion in an ionic liquid electrolyte on the electrochemical performance of a silicon negative electrode for a lithium-ion battery
We investigated the influence of the anions in ionic liquid electrolytes on the electrochemical performance of a silicon (Si) negative electrode for a lithium-ion battery. While the electrode exhibited poor cycle stability in tetrafluoroborate-based and propylene carbonate-based electrolytes, better cycle performance was achieved in bis(fluorosulfonyl)amide (FSA(-))- and bis(trifluoromethanesulfonyl)amide (TFSA-)-based electrolytes, in which the discharge capacity of a Si electrode was more than 1000 mA h g(-1) at the 100th cycle. It is considered that a surface film derived from FSA(-)- and TFSA(-)-based electrolytes effectively suppressed continuous decomposition of the electrolyte. In a capacity limitation test, a discharge capacity of 1000 mA h g(-1) was maintained even after about the 1600th cycle in the FSA(-)-based electrolyte, which corresponds to a cycle life almost twice as long as that in Mir-based electrolyte. This result should be explained by the high structural stability of FSA(-)-derived surface film. In addition, better rate capability with a discharge capacity of 700 mA h g(-1) was obtained at a high current rate of 6 C (21 A g(-1)) in FSA(-)-based electrolyte, which was 7-fold higher than that in TFSA(-)-based electrolyte. These results clarified that FSA(-)-based ionic liquid electrolyte is the most promising candidate for Si-based negative electrodes. (C) 2016 Published by Elsevier B.V.