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Page 6 of 14 Chen et al. Energy Mater. 2025, 5, 500064 https://dx.doi.org/10.20517/energymater.2024.163

Figure 1. Structure of the proposed dual interface design in ASSBs. (A) Schematic representation of a “sandwich” dual protection on
LMA and NCM811 cathode. (B) SEM image of the alucone coated NCM811 cathode. (C) SEM image (i) and EDS mapping of the alucone
coating on LMA: Al element (ii) and O element (iii). (D) Schematics of LLZO/PEO/ LiTFSI film made of PEO, LLZO and LiTFSI. (E)
Fabricated LLZO/PEO/LiTFSI film with a diameter of 18 mm.

does not much alter the ionic conductivity. As shown in Supplementary Figure 3, the ionic conductivity (σ)
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of the LLZO/PEO/LiTFSI film is 1.28 × 10 S cm through the ionic conductivity test at 50 °C. Therefore,
the balance between electrochemical performance and interfacial protection can be maintained when
performing with this ALD coating strategy.
Electrochemical performance of lithium metal anode
Initially, the Li-Li symmetric cells were assembled to illustrate the impact of the alucone coating layer on the
interface stability between LMA and LLZO/PEO/LiTFSI films. Figure 3A shows the cyclic testing on the
cells of LMA|PEO/LITFSI|LMA, LMA| LLZO/PEO/LiTFSI|LMA, and LMA-Alucone|LLZO/PEO/LiTFSI|
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Alucone-LMA under a current density of 0.1 mA cm and a surface capacity of 0.1 mAh cm . The results
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reveal that the originally assembled LMA|PEO/LITFSI|LMA cell exhibits a significant interface resistance
due to the inadequate interface contact which results in considerable polarization voltage and unstable
performance during cycling. The LMA|LLZO/PEO/LiTFSI|LMA cell can improve interface contact a bit,
but the non-uniform deposition sites can lead to premature core short-circuit, indicating that enhancing
[44]
stability of the interface solely through composite electrolyte construction is insufficient . In comparison,
the LMA-Alucone|LLZO/PEO/LiTFSI|Alucone-LMA cell demonstrates a consistent cycling performance,
validating that the alucone coating layer can not only enhance the electrode/electrolyte interface but also
promote uniform lithium deposition. Additionally, as illustrated by the magnified view at the end of cycling
in Figure 3B, alucone coating layers on the electrode interface can also reduce the polarization voltage
(< 50 mV) during cycling. These results above suggest that integrating an alucone coating layer onto a
LLZO/PEO/LiTFSI film can optimize interface contact and enhance the stability of the interface as well.