Figure 1 (a) Illustration of the preparation process of
carbon-supported Li-Si alloy electrodes. (Reproduced from ref.[47],
with permission from Copyright © 2018 The Royal Society of Chemistry.)
(b) Scheme illustrating the high-energy ball-milling process using Li
grains and Si powders as precursors. (Reproduced from ref.[49], with
permission from Copyright © 2014 American Chemical Society.) (c) Hybrid
anodes based on facile and fast Sn deposition on reactive metals
produced by ion exchange in a common used aprotic liquid lithium
electrolyte, 1 M LiPF6 in an ethylene carbonate-dimethyl
carbonate (EC/DMC) solvent blend containing a second salt. (Reproduced
from ref.[59], with permission from Copyright © 2019 Elsevier Ltd..)
Surface morphology and elemental distribution of the cycled (d) Li metal
and (e) Li-Mg alloy anode retrieved from the cells after 100 cycles.
(Reproduced from ref.[76], with permission from Copyright © 2019
WILEY-VCH.)
Even the theoretical of Li-Zn alloy is not as high as Li-Si, Li-Sn,
Li-Ge, Li-Sb alloys, etc., the volume expansion of Li-Zn alloys is not
obvious when used in Li storage[82]. Chen et al. reported a Li-Zn
alloy synthesized by depositing Li on the Zn substrate precursor at a
constant current density of 0.05 mA·cm−2 until the
potential reached 0 V (vs. Li/Li+)[82]. The
efficiency of Li deposition/stripping on the Li-Zn alloy anode remained
high at 96.7% after 400 cycles at a current density of 0.1
mA·cm−2 and 250 cycles at the current density of 0.2
mA·cm−2.
Different from the Si and Sn that experienced reconstitution reaction
with lithium to form alloys, Au and Ag, as two typical noble metals,
involve solid-solution reaction with Li to form
LiAux and LiAgxalloys[83, 84]. The solid-solution reaction involves much less
structure change than its counterpart (e.g. Si and Sn) in the
lithiation-delithiation process, therefore can take place with a low
charge-discharge voltage hysteresis at a potential that is very close to
that of Li/Li+ redox couple and eliminate the
nucleation barriers[83]. For example, in 2016, Cui’s group has found
Au, Ag, Zn and Mg with good solubility in Li, once fully lithiated,
exhibited zero overpotential during deposition of Li as shown in Figure
2a[84]. For materials Al and Pt have relatively small solubility in
Li metal and show small but observable overpotential for Li nucleation
(5 mV for Al, 8 mV for Pt); For materials showing no solubility (Cu, Ni,
C, Sn, Si) in lithium were also tested, as shown in Figure 2b, all five
materials show a clear overpotential for Li metal nucleation. According
to this vital findings, they designed Au nano particles distributed
inside the hollow carbon spheres to selectively nucleate and grow Li
metal inside carbon nanoshells during electrochemical deposition, as
shown in Figure 2c.