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Lv et al. Energy Mater 2024;4:400018 https://dx.doi.org/10.20517/energymater.2023.90 Page 7 of 11

photoelectron spectroscopy (XPS) was used to disclose the chemical state of LM in the composite anode. As
shown in Figure 2C-E, the XPS peak patterns of Ga 3d, Sn 3d and ln 3d in LM-W10/CF and LM/CF are
almost identical; however, some peak positions of LM-W10/CF are shifted by about 0.14 or 0.21 eV towards
the lower binding energy compared to LM/CF (all XPS spectra have been corrected with C1s 284.6 eV). For
the W 4f spectrum in Figure 2F, all peak positions shift more significantly, and the half-peak width is larger;
the peaks at 37.91 and 35.77 eV are shifted towards the low binding energy by about 0.45 and 4.31 eV,
respectively. It indicates that the electronegativity of W increased after composing with LM. Considering the
difference in the electronegativity of W (2.36) > Sn (1.96) > Ga (1.81) > ln (1.78). The charge localization of
GalnSn alloy is weakened after the introduction of strong electronegativity metal W, resulting in the
presence of binding energy shifts. This means that electrons from the GalnSn atoms were transferred to the
W atoms, the electron cloud density around the W atoms will increase when W gets a large number of
electrons, and the binding energy will obviously decrease accordingly. The slight shift of each element in
GalnSn towards the direction of low binding energy may be due to the mixing of W atoms and GalnSn
forming a whole. Although the difference of their electronegativity will lead to charge transfer, the overall
electron cloud density will increase [32-35] .

To evaluate the electrochemical performance of the Li/LM-W10/CF and Li/LM/CF anode, symmetric cells
were assembled to study the reversible Li storage performance. As shown in Figure 3A, both electrodes were
deposited with 1 mAh/cm of Li and assembled into symmetrical cells with two identical electrodes, then
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fixed areal capacity of 0.5 mAh/cm in subsequent repeated cycles. The Li/LM-W10/CF displayed a
relatively low over-potential (~13 mV) and remained stable for more than 8,000 h (4,000 cycles) at a current
density of 0.5 mA/cm . Meanwhile, the Li/LM/CF exhibited an over-potential of ~28 mV, and short-circuit
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occurred after about 3,700 h (~1,850 cycles). Figure 3B shows the performance of samples prestored with
2 mAh/cm of Li and a fixed areal capacity of 1 mAh/cm . The Li/LM-W10/CF showed a low over-potential
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(~27 mV) with a cycle life for more than 8,000 h (4,000 cycles) at 1 mA/cm , while the Li/LM/CF exhibited a
high over-potential of ~39 mV and began to oscillate at 3,400 cycles. This might be caused by non-uniform
lithiation processes and serious SEI accumulation. The Li/LM-W10/CF has a lower lithiation over-potential
(13.4 mV) than that of the Li/LM/CF (20.2 mV) in Figure 3C. And the rate performance of the
Li/LM-W10/CF symmetric battery was further explored [Figure 3D]; the voltage hysteresis increases slightly
from 7 to 30 mV with the increase of the current density from 0.2 to 1 mA/cm . The above results
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demonstrate that the cycling stability and lithiation over-potential of Li/LM-W10/CF is better than that of
Li/LM/CF, which is benefited by the excellent interfacial contact and superior electrochemical kinetics
between CF and Li/LM-W10.

The Li/LM-W10/CF anode was fabricated into full cells coupled with LFP cathodes to investigate its
practical applications. Figure 4A shows the cycling performance of full cells with different anodes at 1C. The
Li/LM-W10/CF||LFP cell presents outstanding stability and maintains at 144 mAh/g with an average
Coulombic Efficiency (CE) of 98.9%. The capacity retention is 95.15% even after 150 cycles with a fading
rate of only 0.032% per cycle. By contrast, the discharge capacities of the Li/LM/CF||LFP and Li/CF||LFP
cells rapidly decayed after 110 and 90 cycles, with relatively low CEs of 94.6% and 92.4%, respectively. The
performance degradation of Li/LM/CF||LFP and Li/CF||LFP full cells is associated with the poor interfacial
contact between originally low content of Li alloy compound and CF surface, which may lead to a "soft
short circuit" within the battery. The poor contact also results in large electrode polarization and Li
consumption in the subsequent cycle, thus deteriorating the life span of the battery.
Supplementary Figure 10 disclosed the corresponding charge/discharge voltage profiles for the Li/LM-W10/
CF||LFP full cell at different cycles. The specific discharge capacities of Li/LM-W10/CF||LFP were 151.8,
141.4, 139.1, and 130.2 mAh/g at 0.2, 0.5, 0.8, and 1C, respectively [Figure 4B], indicating stable charge/