Thursday, 23 June 2016
Riverside Center (Hyatt Regency)
J. Maibach (Department of Chemistry - Ångström, Uppsala University), R. Maripuu (Uppsala University), M. Andersson, S. Urpelainen (MAX IV Laboratory, Lund University), J. Schnadt (Lund University), T. Gustafsson, H. Rensmo (Uppsala University), K. Edstrom (Uppsala University, Sweden), H. Siegbahn, and M. Hahlin (Uppsala University)
Despite the large number of studies targeting surfaces, (buried) interfaces and chemical gradients in battery electrodes, the processes leading to the formation of the solid electrolyte interphase (SEI) are not yet fully understood. Fundamental research on the SEI’s formation process is necessary for controlled design of chemistries that lead to long term stable and functional solid/liquid interfaces in Li-ion batteries. Many of the components suggested to form within the SEI are highly reactive, and may directly upon formation further react with the surrounding components. Since most studies are performed post-mortem meaning after the battery has been taken apart, a missing key point is the study of the SEI formation process in real time. Ambient pressure photoelectron spectroscopy (AP-PES) offers the possibility to obtain more realistic information about the formation of these sensitive interfaces as experiments can be conducted at elevated pressures and with liquids present.
We will present results from our recent advances within the field of characterizing battery materials using AP-PES. This includes a new AP-PES instrumentation developed in Uppsala [1] together with a novel methodology for the direct investigation of the interface between the solid electrode and liquid electrolyte [2]. The latter technique was demonstrated with a Li-ion battery and for the first time enabled the study of the SEI in the Si|LiClO4in PC|Li battery system with the electrolyte present. The results show that the SEI composition for the wet electrode is stable within the probing time and generally agrees well with traditional UHV studies.
Using advanced near ambient pressure cell design at the SPECIES beamline at MAX-lab [3], we have studied Li metal in presence of PC vapor and for the first time in contact to a droplet of liquid PC (see Figure 1). The results from these studies concerning PC adsorption, stability during measurement conditions and radiation exposure are the basis for further electrolyte characterizations and the development of an in-situ electrochemistry cell, which will enable battery electrode cycling directly in the AP-PES setup.
References
[1] S. K. Ericsson et al., Rev. Sci. Inst. 85 (2014), 075111/1
[2] J. Maibach et al., Rev. Sci. Inst. 86 (2015), 044101
[3] J. Schnadt et al., J. Synchrotron Rad. 19 (2012), 701-704
