Journal
JOURNAL OF POWER SOURCES
Volume 349, Issue -, Pages 1-10Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2017.03.025
Keywords
Mechanics; Si microwires; FFT-impedance spectroscopy; Cyclic voltammetry; Charge transfer
Funding
- German Research Foundation as part of the project Elektrochemische und mikrostrukturelle Untersuchung der Prozesse in Anoden fur Hochkapazitats-Lithium-Ionen-Batterien basierend auf Si-Mikrodrahtanordnungen [FO 258/17-1]
Ask authors/readers for more resources
Perfectly aligned silicon microwire arrays show exceptionally high cycling stability with record setting (high) areal capacities of 4.25 mAh cm(-2). Those wires have a special, modified length and thickness in order to perform this good. Geometry and sizes are the most important parameters of an anode to obtain batteries with high cycling stability without irreversible losses. The wires are prepared with a unique etching fabrication method, which allows to fabricate wires of very precise sizes. In order to investigate how good randomly oriented silicon wires perform in contrast to the perfect order of the array, the wires are embedded in a paste. This study reveals the fundamental correlation between geometry, mechanics and charge transfer kinetics of silicon electrodes. Using a suitable RC equivalent circuit allows to evaluate data from cyclic voltammetry and simultaneous FFT-Impedance Spectroscopy (FFT-IS), yielding in time resolved resistances, time constants, and their direct correlation to the phase transformations. The change of the resistances during lithiation and delithiation correlates to kinetics and charge transfer mechanisms. This study demonstrates how the mechanical and physiochemical interactions at the silicon/paste interface inside the paste electrodes lead to void formation around silicon and with it to material loss and capacity fading.(C) 2017 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available