We report an in situ scanning tunneling microscopic study of surface morphology changes in Au（111） electrode in 1-ethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide （EMITFSI） ionic liq- uid containing L...We report an in situ scanning tunneling microscopic study of surface morphology changes in Au（111） electrode in 1-ethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide （EMITFSI） ionic liq- uid containing LiTFSI salt. The surface processes can be divided into three stages： In the first stage, a re- duction wave of dissolved oxygen in the ionic liquid appears at approximately 2.0 V and a network structure covers the surface afterward; in the second stage at around 1.5 V, reduction of trace water is initiated and a surface film containing lithium hydroxide is formed; in the third stage, as potential is further decreased to 0.85 V, decomposition of the EMITFSI ionic liquid occurs, which is accompanied by lithium underpotential deposition and Au-Li alloying. In this stage, the surface experiences significant morphological changes with formation of many clusters on the surface, and even- tually becomes electronically less conductive. This unique surface film is understood to be the initial stage formation of a solid electrolyte interphase on gold, which may be a common feature in ionic liquids in the presence of lithium salt.展开更多
基金supported by the National Basic Research Program of China(2012CB932902)the National Natural Science Foundation of China(21033007,20973144,21321062)
文摘We report an in situ scanning tunneling microscopic study of surface morphology changes in Au（111） electrode in 1-ethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide （EMITFSI） ionic liq- uid containing LiTFSI salt. The surface processes can be divided into three stages： In the first stage, a re- duction wave of dissolved oxygen in the ionic liquid appears at approximately 2.0 V and a network structure covers the surface afterward; in the second stage at around 1.5 V, reduction of trace water is initiated and a surface film containing lithium hydroxide is formed; in the third stage, as potential is further decreased to 0.85 V, decomposition of the EMITFSI ionic liquid occurs, which is accompanied by lithium underpotential deposition and Au-Li alloying. In this stage, the surface experiences significant morphological changes with formation of many clusters on the surface, and even- tually becomes electronically less conductive. This unique surface film is understood to be the initial stage formation of a solid electrolyte interphase on gold, which may be a common feature in ionic liquids in the presence of lithium salt.
