Figure 9 (a) Schematic representation for improving the contact
between garnet and Li metal by engineering the surface of the garnet
with a thin Ge layer. The Ge layer, evaporated onto garnet, can alloy
with Li metal, which leads to more continuous interfaces between the
garnet and Li metal and results in a small interfacial resistance. (b)
Schematic of the full cell structure, where a gel membrane was used
between garnet and LFP cathode. (c) Cycling performance of the
Li/Ge-modified-garnet/LFP cell and Li/liquid-electrolyte/LFP cell at 1
C. (d) Coulombic efficiencies of Li/Ge-modified-garnet/LFP cell and
Li/liquid-electrolyte/LFP cell at 1 C. (Reproduced from ref.[126],
with permission from Copyright © 2017 Wiley-VCH.)
Since then, the Li-Zn, Li-Sn and Li-Mg alloy modified garnet solid
electrolytes have subsequently developed[123-125]. Such a facile
surface treatment on garnet electrolyte with forming lithium alloys
method offered a simple strategy to solve the interface problem in
solid-state lithium metal batteries.
3.5 | Lithium Alloys modified
separators
A multifunctional separator through coating a thin electronic conductive
film on one side of the conventional polymer separator facing the Li
anode could contribute to Li dendrite suppression and cycling stability
improvement[127]. Recently, Li and his co-workers developed a
multifunctional lithium alloys coating separator by reducing the
PbZr0.52Ti0.48O3 (PZT)
coating layer on polypropylene (PP) separator[128]. The produced
Li-Pb alloy armor between the separator and Li anode, not only uniformed
the electric field across the interface but also mitigated the Li metal
nucleation, and therefore suppressed the dendrite growth during plating.
As a result, the Li/Li symmetric cells and LiFePO4/Li
cells with this such PZT-pretreated PP separators exhibit significantly
improved Coulombic efficiency and cycling life as shown in Figure 10a
and 10b.