Solid-state lithium-based batteries offer higher energy density than their Li-ion counterparts. Yet they are limited in terms of negative electrode discharge performance and require high stack pressure during operation. To circumvent these issues, we propose the use of lithium-rich magnesium alloys as suitable negative electrodes in combination with Li₆PS₅Cl solid-state electrolyte. We synthesise and characterise lithium-rich magnesium alloys, quantifying the changes in mechanical properties, transport, and surface chemistry that impact electrochemical performance. Increases in hardness, stiffness, adhesion, and resistance to creep are quantified by nanoindentation as a function of magnesium content. A decrease in diffusivity is quantified with ⁶Li pulsed field gradient nuclear magnetic resonance, and only a small increase in interfacial impedance due to the presence of magnesium is identified by electrochemical impedance spectroscopy which is correlated with x-ray photoelectron spectroscopy. The addition of magnesium aids contact retention on discharge, but this must be balanced against a decrease in lithium diffusivity. We demonstrate via electrochemical testing of symmetric cells at 2.5 MPa and 30^∘C that 1% magnesium content in the alloy increases the stripping capacity compared to both pure lithium and higher magnesium content alloys by balancing these effects.

固态锂电池提供比锂离子电池更高的能量密度。然而，它们在负极放电性能方面受到限制，并且在运行期间需要高堆栈压力。为了规避这些问题，我们建议将富锂镁合金作为合适的负极与 Li₆PS₅Cl 固态电解质结合使用。我们合成和表征富锂镁合金，量化影响电化学性能的机械性能、传输和表面化学的变化。硬度、刚度、粘附力和抗蠕变性的增加通过纳米压痕作为镁含量的函数进行量化。用 ⁶Li 脉冲场梯度核磁共振量化扩散率的降低，并且通过与 X 射线光电子能谱相关的电化学阻抗谱确定由于镁的存在而导致的界面阻抗仅略有增加。镁的添加有助于放电时的触点保持，但这必须与锂扩散率的降低相平衡。我们通过在 2.5 MPa 和 30^∘C 下对称电池的电化学测试证明，与纯锂和更高镁含量的合金相比，合金中 1% 的镁含量通过平衡这些效应提高了剥离能力。