Hongyan Yao

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.

Solid-state electrolytes (SSEs), particularly garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO), offer high stability and a wide electrochemical window. However, their grain boundaries limit ionic conductivity, necessitating high-temperature sintering for improved performance. Yet, this process results in brittle electrolytes prone to fracture during manufacturing. To address these difficulties, solvent-free solid-state electrolytes with a polyacrylonitrile (PAN) coating on LLZTO particles are reported in this work. Most notably, the PAN-coated LLZTO (PAN@LLZTO) electrolyte demonstrates self-supporting characteristics, eliminating the need for high-temperature sintering. Importantly, the homogeneous polymeric PAN coating, synthesized via the described method, facilitates efficient Li⁺ transport between LLZTO particles. This electrolyte not only achieves an ionic conductivity of up to 2.11 × 10⁻³ S cm⁻¹ but also exhibits excellent interfacial compatibility with lithium. Furthermore, a lithium metal battery incorporating 3% PAN@LLZTO-3%PTFE as the solid-state electrolyte and LiFePO₄ as the cathode demonstrates a remarkable specific discharge capacity of 169 mAh g⁻¹ at 0.1 °C. The strategy of organic polymer-coated LLZTO provides the possibility of a green manufacturing process for preparing room-temperature sinter-free solid-state electrolytes, which shows significant cost-effectiveness.