PNNL

Abstract

Lithium batteries with Si, Al or Bi microsized (>10 µm) particle anodes promise high capacity, ease of production, low cost and lesser environmental impact, yet they suffer from fast degradation and low Coulombic efficiency (CE). Here we demonstrate that a rationally designed electrolyte (2 M LiPF6 in 1:1 v/v mixture of tetrahydrofuran and 2-methyl tetrahydrofuran) enables 100 cycles of full cells containing microsized Si, Al and Bi anodes with commercial LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes. Alloy anodes with areal capacities of more than 2.5 mAh cm-2 achieved >300 cycles with high initial CE of >90% and average CE of >99.9%.These improvements are facilitated by the formation of a high modulus LiF|organic bilayer interphase possessing high interfacial energy with the alloy anode to accommodate plastic deformation of the lithiated alloy during cycling. This work provides a simple yet practical solution to current battery technology without any binder modification or special fabrication methods.