High Areal Loading Silicon Nanoparticle-Based Lithium-Ion Batteries

Interfacial mechanical stability between silicon (Si) and the current collector is crucial when high areal-loading of Si is demanded as intense stress develops at the interface due to its extreme volume alteration during the lithiation-delithiation process. Therefore, we propose using a thin, rough, porous, and highly conductive carbon nanotube network (CNT-N) as a buffer layer between the Si and current collector that provides abundant anchor sites for Si nanoparticles. The strong and elastic CNT-N, which is not involved directly in the lithiation process, reduces stress at interfaces between the Si and CNT-N and the CNT-N and current collector. We successfully fabricated a Si anode and NMC cathode with areal loadings of 6.13 mg cm^-2 (7.65 mA h cm^-2 at 1 mA cm^-2) and ∼80 mg cm^-2 (∼17 mA h cm^-2 at 1 mA cm^-2), respectively. Besides, a full cell composed of the Si anode (W_Si+CNTs = 6.13 mg cm^-2) and NMC cathode (W_NMC = 35 mg cm^-2) at 1 mA cm^-2 exhibited an initial Coulombic efficiency (ICE) and capacity of 85.1% and 7.14 mA h cm^-2, respectively. Despite the cell's continuous capacity fade (∼4 mA h cm^-2 at 100th cycle), the bilayer design may pave the way for achieving high areal-loading Si-based anodes for high-energy-density lithium-ion batteries.