A 3D-printed framework with a gradient distributed heterojunction and fast Li+ conductivity interfaces for high-rate lithium metal anodes

Abstract

A bottleneck limiting the practical application of lithium metal anodes is the uncontrolled growth of lithium dendrites caused by gradient distributed Li⁺ from separators to collectors. Herein, 3D-printed frameworks with a gradient distributed heterojunction and fast Li⁺ conductivity interfaces are developed to regulate the Li⁺ distribution and the direction of dendrite growth. More importantly, the effect of different Li⁺ concentration gradient frameworks on Li⁺ deposition behavior was analyzed in detail. Synchrotron X-ray tomography demonstrates that macropores dominate the framework, which effectively suppresses the volume change caused by lithium deposition. DFT calculations confirm the high lithiophilicity of γ-Al₂O₃ and the graphene heterojunction. Synchrotron radiation-based soft X-ray absorption spectroscopy illustrates the fast Li⁺ conductivity Li–Al–O interface resulting from the shortened Al–O bond distance. Benefiting from the higher Li⁺ concentration differences during the dissolution process and Li–Al–O interfaces, the gradient framework can achieve a high rate performance of ∼40 mV overpotential at 10 mA cm⁻² and long cycle stability of ∼1500 h at 1 mA cm⁻².