Until now, a key barrier toward realizing a high energy density Mg²⁺ battery has been the limited understanding of mechanisms governing multivalent metal electrodeposition. This, compounded with recent observations of Mg dendrites, highlights the need for better fundamental insight into multivalent systems. We present a comprehensive study of electrodeposition in practical coin-cell configurations to evaluate the mechanisms of growth from common Mg(TFSI)₂-based electrolytes. Our findings indicate a transition from charge-transfer-limited to diffusion-limited electrodeposition processes that govern the morphological evolution of Mg deposits. We observe the signature of cell shorting under a wide range of current densities that we attribute to 3D hemispherical growth of Mg deposits that form under mixed diffusion and kinetic control and are distinguished from traditional fractal dendrites. Our results highlight synergy with classical electrochemical theories for growth and lay groundwork for future approaches to achieve stable electroplated multivalent metal electrodes.

到目前为止，实现高能量密度Mg ²⁺电池的关键障碍是对控制多价金属电沉积机理的有限理解。这与最近对Mg树枝状晶体的观察相结合，突显了对多价系统有更好的基础洞察力的需要。我们提出了一种在实际纽扣电池配置中进行电沉积的综合研究，以评估普通Mg（TFSI）₂的生长机理基电解质。我们的研究结果表明，从电荷转移受限到扩散受限的电沉积过程的转变决定了镁沉积物的形态演变。我们在广泛的电流密度下观察到细胞短路的信号，我们将其归因于Mg沉积物的3D半球形生长，该沉积物是在混合扩散和动力学控制下形成的，与传统的分形树突相区别。我们的研究结果突出了与经典电化学理论的协同作用，为增长提供了基础，并为实现稳定的电镀多价金属电极的未来方法奠定了基础。