Si-aonde Lithium ion battery
Silicon anode LIB advantages:
- High theoretical gravimetric capacity of ~4,200 mAh g−1
- Better lithium plating protection and better safety, due to 140-mV higher lithiation potential (ref)
- Relatively low discharge potential (~0.5 V versus Li/Li+)
- Natural abundance of elemental Si
Silicon anode major challenges
- Fracture and loss of electrical contact. Large volumetric fluctuations during lithiation and delithiation-> Anode pulverization. The volume change is up to 320%.
- Unstable solid electrolyte interphase (SEI) growth on the Si surface. SEI formation (volumetric expansion during lithiation ->break during delithiation (Si shrinking)->SEI reformation (Si expansion), during cycling.
- Drastic irreversible capacity loss and low coulombic efficiency is caused by mechanical fracture of Si anodes during the alloying/dealloying process.
- Low electrical conductivity for pure Si anode
- Lithium trapping at formation. “pre-lithiation” process during manufacturing to insert additional lithium to top-off lithium trapped at formation (ref)
Solutions
Confine Si nanoparticle (SiNP) with conductive polymer network
PANi in-situ synthesized on the surface of SiOx-Si to have at least two functions:
- Form a conformable coating on the surface of SiNP to absorb the volumetric deformation during litigation/delithiation.
- Confine SiNP within the network of PANi, a conductive polymer.
Confine Si particles within carbon or between graphite sheets
Example of Silicon Battery
