So I made silicon anode from slurry that consists of silicon micro/nanoparticles + binder + conductive carbon. The anode generates high spesific capacity (above 2000 mAh/g) only at very low current density (10-20 mA/g). When tested at higher current density (50-100 mA/g), the anode charged/discharged rapidly and generated very low spesific capacity. Any suggestion for this issue? Thank you in advance.
I used CMC as binder, Super P as conductive agent, and Si particle size of mainly distributed near 3 micrometer. The initial discharge capacity was around 800 mAh/g. Do you have experience in preparing similar silicon anode? Would you mind to share your experience? Thank you.
A Silicon/carbon grain (or/and similar) based strategies might help your next studies[1-3].
1. Review of Nanotechnology for Anode Materials in Batteries https://www.sciencedirect.com/topics/engineering/silicon-anode
2. Silicon-Carbon composite anodes from industrial battery grade silicon https://www.nature.com/articles/s41598-019-51324-4
3. High Energy Density and Specific Energy Silicon Anode-Based Batteries http://powersourcesconference.com/Power%20Sources%202018%20Digest/docs/13-2.pdf
Hello Ansor Prima Yuda
Silicon anode has ability to hold 10 times more the electrical charge per gram as compared to graphite. The theoretical capacity of Si is (4200 mA h g−1 , calculated from the Si weight corresponding to Li4.4Si) which is 10 times higher than the graphite anodes (372 mA h g−1 ). The trouble is that, silicon expands greatly when it encounters with lithium, and this volume expansion results in pulverization of electrode. So to overcome this issue we can use many strategies such as making nano-structured Si materials with various morphologies (e.g., hollow structures, nanowires, and nanotubes) using inactive materials as a buffer layer, and using additional active materials as additives for the primary Si material, like carbon nanotubes, reduced graphene oxides or metal organic framework.
In your case you already mention that your anode is made up of some macroparticles so macroparticles show more expansion that will result in electrode cracking so definitely results in fast charging and discharging. I recommend you to decrease the particle size of your material or make it porous or use any conductive buffer material.
Here I am going to attach two of my papers based on Si anode material. hope so they would be fruitful for you.
Use high molecular weight CMC with SBR, use about 5-10 % Binder in your slurry. Try using more carbon. Addition of carbon fibers (CNF, CNT) might help adhesion and conductivity.
Try thin electrode coatings and also calander your electrodes
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