Insights into solid electrolyte interphase formation on alternative anode materials in lithium-ion batteries

Abstract

To gain new insights into the formation of the solid electrolyte interphase (SEI), as a basis for the safe and efficient use of new anode materials, we studied SEI formation on silicon and lithium titanate (LTO) anodes by electrochemical impedance spectroscopy (EIS) and ex situ X-ray photoelectron spectroscopy (XPS) measurements. While EIS measurements performed at equidistant voltage intervals provided insights into the SEI formation process, ex situ X-ray photoelectron spectroscopy (XPS) measurements supplied data on the chemical composition of the SEI layer. On silicon anodes we observed that resistance decreases in the second cycle which suggests the formation of a stable SEI with SiO 2 , Li 4 SiO 4 , LiF and different carbonates as its main components. On LTO anodes, however, resistance increases by a factor of two indicating incomplete SEI formation. Here LiF and different carbonates were identified as the SEI's main components.

Highly efficient poly(fluorene phenylene) copolymer as a new class of binder for high-capacity silicon anode in lithium-ion batteries

“…These peaks are related to aliphatic and aromatic hydrocarbons in the polymer binder. 62 After 5 cycles, new peaks are also seen in the F1s spectrum at 686 eV and P2p spectrum at 134.5 eV which indicates characteristic of Li x PF y , Li x PF y O z , and LiF. 63 These new peaks demonstrate the changes of the elemental concentrations.…”

Comprehensive Aging Analysis of Volumetric Constrained Lithium-Ion Pouch Cells with High Concentration Silicon-Alloy Anodes

“…It is widely reported in the literature that silicon anodes endure substantial volumetric expansion/contraction (280-400%) due to repeated (de-)lithiation, giving rise to high internal stresses within the anode, which lead to continuous repair of the damaged SEI and ultimately result in the consumption of cyclable lithium and capacity fade [3,[5][6][7][8][9][10][11][12][13][14]. In an initial effort to monitor this characteristic behavior, it was observed that applying external pressure perpendicular to the cell's electrodes by constraining it volumetrically improved both its energy and power capabilities, as reported in our previous work [21].…”

“…Silicon (Si) presents an attractive alternative to the graphite anode material currently used in conventional Li-ion batteries owing to its natural abundance, significantly higher volumetric capacity and specific capacity (2194 Ah/l vs. 719 Ah/l for Li 15 Si 4 and LiC 6 ; 3579 mAh/g vs. 372 mAh/g for Si and graphite) [3,4]. However, Si anodes have shown poor cyclability as a result of substantial volumetric expansion/contraction (280-400%) [3,[5][6][7][8][9][10][11][12][13][14] due to repeated (de-)lithiation, giving rise to high internal stresses within the anode. Plenty of research [5][6][7][8][9][10][11][12][13][15][16][17] is available in the literature, identifying the aging mechanisms induced by electrochemical cycling of Si anode half-cells as: (1) deterioration of the electrode's structural integrity due to pulverization; (2) disconnection between the current collector and electrode due to (de-)lithiation-induced stress; (3) consumption of cyclable lithium in the reformation process of the damaged Solid Electrolyte Interface (SEI).…”

High-throughput battery materials testing based on test cell arrays and dispense/jet printed electrodes

“…Thus, until now the great majority of battery experiments is conducted based on single cell preparation. Coin cells and pouch packaged cells are used for two-electrode measurements while three-electrode measurements are carried out with sophisticated mechanical constructions like T-cells (Garcia et al 2016;Loveridge et al 2016) or El-cells (Steinhauer et al 2017).…”