Silicon-Based Composite Anodes for All-Solid-State Lithium-Ion Batteries Conceived by a Mixture Design Approach.

Silicon-based anodes composed of micrometric Si, graphite (MAG), LiI-Li3 PS4 solid electrolyte (LPSI), and carbon nanofiber (CNF), which can be prepared by straightforward manual grinding, are proposed in this study. The relation between composition and performance of the anodes is investigated through the mixture design approach, which allows discrimination of the effect of each component and also the combined effect of the components on the end performance. By increasing the fraction of LPSI in the anode, the capacity of the electrode is improved, and the best performance is obtained when the Si/MAG/LPSI ratio is 15 : 15 : 70. This composite integrated with 5 wt % CNF exhibits a capacity above 1200 mAh g-1 throughout 50 cycles in a bulk-type all-solid-state battery with LPSI as the electrolyte. Scanning electron microscopy (SEM) confirms that the presence of LPSI suppresses the aggregation of Si and improves the ratio of Si available for lithiation/delithiation.

Silicon-Carbon composite anodes from industrial battery grade silicon.

In this work, silicon/carbon composites for anode electrodes of Li-ion batteries are prepared from Elkem's Silgrain® line. Gentle ball milling is used to reduce particle size of Silgrain, and the resulting Si powder consists of micrometic Si with some impurities. Silicon/carbon composite with CMC/SBR as a dual binder can achieve more than 1200 cycles with a capacity of 1000 mAh g-1 of Si. This excellent electrochemical performance can be attributed to the use of a buffer as a solvent to control the pH of the electrode slurry, and hence the bonding properties of the binder to the silicon particles. In addition, the use of FEC as an electrolyte additive is greatly contributing to a stabilized cycling by creating a more robust SEI layer. This work clearly demonstrates the potential of industrial battery grade silicon from Elkem.