Gradient Multisite Adsorption of Porous Al-Based Anodes for Fast and Uniform Lithium Kinetic Transport

Metallic Al is an attractive anode material in lithium-ion batteries (LIBs) owing to its relatively high theoretical capacity, low cost, and natural abundance. However, the practical application of Al-based anodes is impeded by issues such as significant volume change, low Coulombic efficiency, growth of dendrites, and sluggish lithium-ion transport during cycling. Herein, we design the inorganic-organic hybrid materials composed of poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with controllable morphologies and porosity to construct a 3D transport channel and gradient multisite adsorption for Li⁺ on the Al anode surface. Benefiting from the uniform porous structure and stronger adsorption effect of the PEO-LiTFSI, Li⁺ is first adsorbed onto PEO-LiTFSI, redistributing Li-ion flux. Second, the adsorbed Li⁺ and Li⁺ in LiTFSI undergo an alloying reaction with the Al anode. The two reaction processes redistribute Li-ion flux and ensure more homogeneous transport properties compared to the direct alloying reaction with Al. As a result, the NCM||Al-PEO-LiTFSI cell delivered stable cycling behavior over 500 cycles under a high 1 C cycling rate, achieving a capacity retention rate of 92.8%. The excellent rate performance was also achieved at 222.4 mA h/g at 5 C, indicating the superior practical application prospect of Al-based batteries. The proposed surface modification strategy furnishes a practicable pathway for the construction of highly stable Al anodes, thereby enabling their potential for practical applications.