Rectifying interphases for preventing Li dendrite propagation in solid-state electrolytes

Solid-state electrolytes have emerged as the grail for safe and energy-dense Li metal batteries but still face significant challenges of Li dendrite propagation and interfacial incompatibility. In this work, an interface engineering approach is applied to introduce an electronic rectifying interphase between the solid-state electrolyte and Li metal anode. The rectifying behaviour restrains electron infiltration into the electrolyte, resulting in effective dendrite reduction. This interphase consists of a p-Si/n-TiO2 junction and an external Al layer, created using a multi-step sputter deposition technique on the surface of garnet pellets. The electronic rectifying behaviour is investigated via the asymmetric I-V responses of on-chip devices and further confirmed via the one-order of magnitude lower current response by electronic conductivity measurements on the pellets. The Al layer contributes to interface compatibility, which is verified from the lithiophilic surface and reduced interfacial impedance. Electrochemical measurements via Li symmetric cells show a significantly improved lifetime from dozens of hours to over two months. The reduction of the Li dendrite propagation behaviour is observed through 3D reconstructed morphologies of the solid-state electrolyte by X-ray computed tomography.

Automated summary

In this study, an interface engineering approach is used to address the challenges of Li dendrite propagation and interfacial incompatibility in solid-state electrolytes for Li metal batteries. By introducing an electronic rectifying interphase consisting of a p-Si/n-TiO2 junction and an external Al layer, electron infiltration into the electrolyte is effectively restrained, leading to dendrite reduction. Experimental results confirm the electronic rectifying behavior of the interphase, as well as improved interface compatibility and battery lifetime. X-ray computed tomography observation confirms the reduction of Li dendrite propagation behavior.