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Wang et al. Energy Mater 2024;4:400031 https://dx.doi.org/10.20517/energymater.2023.103 Page 3 of 11

pores as the sub-skeleton, which can not only confine the Li deposition/dissolution behavior in the limited
space but also tackle the wettability issue of the carbon-based primary framework, leading to the improved
performance of Li composite anodes.

Recently, it has been shown that generating Li-rich Li-X (where X denotes metallic element) alloy by doping
other metals into liquid Li can significantly facilitate rapid spreading of molten Li by reducing surface
tension [53-55] . In addition, the formed Li alloy phase can act as a 3D framework to regulate Li stripping/
plating process for prolonged cyclic lifetime. The geometric structure and physicochemical nature of the Li
alloy framework are critical for advanced performance of Li composite anodes. Our group found that dual-
phase Li-barium (Ba) alloy has a unique micro-sized ordered array of BaLi microchannels, which can
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+
homogenize Li flux and provide active sites for inducing the uniform Li deposition . However, the long-
[56]
term cyclic stability cannot be guaranteed due to the insufficient robustness of the Li-Ba alloy scaffold.
Herein, we infiltrate the molten Li-rich Li-Ba alloy composed of BaLi intermetallic compounds and Li
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metal phases into the CC sheet to fabricate a Li-Ba alloy composite anode (named LBAC). Doping of
metallic Ba can significantly lower the binding force among Li atoms, allowing the molten liquid alloy to
diffuse rapidly into the CC host. In addition, the BaLi alloy scaffold is in situ created by phase separation
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during the cooling process. The porous architecture of BaLi skeleton with strong lithiophilicity is nested in
4
conductive carbon fiber network as the sub-framework, which provides larger surface area for the
nucleation of Li and confines Li stripping/plating in microchannels of BaLi alloy framework, thus
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suppressing the Li dendrite growth efficiently. Moreover, the structural stability of the Li-Ba alloy is
enhanced by the strong flexibility exhibited by the CC. As a result, the LBAC anode displays favorable
cycling performance, achieving ultra-long cycle lifespan (> 1,000 h) at 1 mA cm and 1 mA h cm in a
-2
-2
symmetric cell with carbonate-based electrolyte. The LBAC/LiFePO (LFP) full cell also displays
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outstanding long-term cycling lifespan and rate performance.

EXPERIMENTAL
Fabrication of LBAC electrode
The stainless steel (SS) foil was utilized as a substrate for the combination of metallic Li (99.5%, Chengdu
Denway Newtype Metal Material Co., Ltd) and Ba (99.5%, Aladdin), with a molar ratio of 1:25. Then, the
temperature was raised to 400 °C. A circular CC sheet measuring 12 mm in diameter was placed on the
molten Li-Ba alloy after the complete dissolution of metallic Ba into liquid Li. The liquid Li-Ba alloy was
quickly infiltrated into the CC sheet. Finally, the LBAC electrode was fabricated via a quick cooling
treatment. All the operations were performed in an argon-filled glove box (Mikrouna, O < 0.01 ppm,
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H O < 0.01 ppm). As a reference, except that the temperature was 500 °C, the Li-C anode was prepared by
2
infiltrating the molten Li into the CC sheet.

Materials characterization
The LBAC anode and CC were recorded by X-ray diffraction (XRD) from 10 to 90° at 5° min (Cu Kα,
-1
0.15456 nm). The anode morphology was characterized using field emission scanning electron microscopy
(FE-SEM) with an acceleration voltage of 20 kV.

Electrochemical measurements
The CR2032-type coin cells were utilized for the assembly of all cells, which were subsequently subjected to
testing on a CT2001A battery testing system (LAND Electronic Co. Ltd.) at 25 °C. The working electrodes
of symmetrical cells were LBAC, Li-C, or Li-Ba sheets. To standardize, symmetric cells were prepared using
an electrolyte containing 100 μL of LiPF (1 M) dissolved in a mixture of ethylene carbonate and diethyl
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carbonate (EC/DEC, v:v = 1:1), supplemented with 5% fluoroethylene carbonate (FEC). As a separator,