Anodes for Lithium Ion Batteries Produced from Recovered Silicon Powders

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
T. Mokkelbost, N. P. Wagner, E. Sheridan, J. R. Tolchard (SINTEF Materials and Chemistry), G. Noja (Garbo S.r.l.), and M. Bellmann (SINTEF Materials and Chemistry)
Lithium Ion Batteries (LIB) offers the highest energy density among rechargeable batteries technologies. However, improvement in materials are needed for LIB in order to increase energy density, safety, durability, decrease cost and allow the further deployment of technologies like electric vehicles and energy storage. One way to improve these batteries is to develop new electrodes, both cathode and anode, resulting in higher energy density. Graphite is today used as anode materials, but Silicon has been extensive studied due to their approximately 10 times higher gravimetrical capacity. However, it is well known that silicon has challenges related to volume expansion during (de)lithiation upon cycling. Several proposed solutions, like nanostructuring, nanowires, encapsulation etc. have been proposed. Here we present initial work, using Silicon kerf (recovered Silicon powders from cutting of silicon ingots).

Silicon kerf was delivered by the ECOSOLAR partner Garbo S.r.l. and the materials were cleaned to remove most of the impurities. The electrochemical performance of Silicon kerf was investigated in half cells. The silicon was mixed with Super C 65 carbon black as conducting agent and Na CMC as binder. Na CMC was dissolved in an aqueous solution containing KOH and citric acid at pH 3 to facilitate chemical bonding between the binder and the active material. Electrodes were fabricated by tape casting on plain Cu foil as current collector. Casts with varying thickness were produced to investigate the effect of electrode loading. C2016 coin cells was prepared using electrolyte consisted of 1M LiPF6 dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1 by vol) added 5 wt% FEC (fluoroethylene carbonate).

Initial studies for using silicon kerf as a source for high capacity anode materials in lithium ion batteries has demonstrated that kerf should be evaluated further to determine the long time cycling stability of this materials. The materials were evaluated both to determine the maximum capacity and stability using capacity limited cycling. The electrodes using Si kerf were stable for 150 cycles during capacity limited cycling using a loading of 0.6 mg/cm3 and a bit lower cycle stability for electrodes with higher loading. It must be highlighted that the electrode structures and composition, electrolyte composition etc. has not been optimized.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 679692.