To summary, table 1 has make conclusions about the various kinds of
binary and multi-component Li-containing alloys anodes as well as their
advantages and disadvantages. As can be seen, there are not perfect
lithium alloys used as the anodes. It is impossible to solve the problem
simply by replacing lithium metal with lithium alloys. Thus, combining
the lithium alloys with other materials, such as graphene, polymers,
etc., to overcome the weak links of lithium alloys have been proposed.
In order to solve some of the lithium alloys instability in air, Cui’s
group developed densely packed Lix M (M=Si, Sn, or
Al) nanoparticles encapsulated by large graphene sheets as shown in
Figure 3a[39]. With the
protection of graphene sheets, the large and freestanding
Lix M/graphene foils are stable in different air
conditions. Among the representative
Lix Si/graphene foil maintained a stable structure
and cyclability in half cells (400 cycles with 98% capacity retention).
And when paired with high-capacity Li-free
V2O5 and sulfur cathodes, stable
full-cell cycling could also achieve. And the alloy electrodes have a
high reduction potential, leading to low energy density. To overcome
drastic volume variation during Li insertion/extraction cycles, except
to prepare superfine alloy particles that have small absolute volume
variation or constructing ternary alloy that contain an inactive metal
to inhibit the great volume expansion, but also can encapsulate the
lithium alloys in the flexible and elastic polymer matrix. For example,
Cui’s group reported a polymer supported Li-Zn alloy structure as shown
in Figure 3b[100]. They used the ALD method to deposit the ZnO on
the polymide (PI) fiber. The core-shell PI-ZnO matrix was put into
contact with molten Li, ZnO reacted with molten Li to form Li-Zn alloy
and simultaneously extra Li can be drawn into the polymer matrix,
affording a Li-coated PI electrode. Thanks to the polymer shell, the
lithium alloys crack and pulverization can be alleviated.