Tang Tian, Zheng J X Kent, Archer Lynden A
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
JACS Au. 2024 Mar 15;4(4):1365-1373. doi: 10.1021/jacsau.3c00721. eCollection 2024 Apr 22.
Controlling the morphological evolution of electrochemical crystal growth in battery anodes is of fundamental and practical importance, particularly towards realizing practical, high-energy batteries based on metal electrodes. Such batteries require highly reversible plating/stripping reactions at the anode to achieve a long cycle life. While conformal electrodeposition and electrode reversibility have been demonstrated in numerous proof-of-concept experiments featuring moderate to low areal capacity (≤3 mA h/cm) electrodes, achieving high levels of reversibility is progressively challenging at the higher capacities (e.g., 10 mA h/cm), required in applications. Nonplanar, "3D" electrodes composed of electrically conductive, porous substrates are conventionally thought to overcome trade-offs between reversibility and capacity because they hypothetically "host" the electrodeposits in an electronically conducting framework, providing redundant pathways for electron flow. Here, we challenge this hypothesis and instead show that a nonplanar substrate with moderate electrical conductivity (ideally, with an electrical conductance similar to the ionic conductance of the electrolyte) and composed of a passivated cathode-facing surface efficiently regulates electro-crystallization. In contrast, an architecture with a high intrinsic electrical conductivity or with a high electrical conductivity coating on the front surface results in dominantly out-of-plane growth, making the 3D architecture in effect function as a 2D substrate. Using Zn as an example, we demonstrate that interconnected carbon fiber substrates coated by SiO on the front and Cu on the back successfully ushers electroplated Zn metal into the 3D framework at a macroscopic length scale, maximizing use of the interior space of the framework. The effective integration of electrodeposits into the 3D framework also enables unprecedented plating/stripping reversibility >99.5% at high current density (e.g., 10 mA/cm) and high areal capacities (e.g., 10 mA h/cm). Used in full-cell Zn||NaVO batteries with stringent N/P ratios of 3:1, the substrates are also shown to enhance cycle life.
控制电池阳极中电化学晶体生长的形态演变具有重要的基础和实际意义，特别是对于实现基于金属电极的实用高能电池而言。此类电池要求阳极具有高度可逆的电镀/脱镀反应，以实现长循环寿命。虽然在许多以中低面积容量（≤3 mA h/cm²）电极为主的概念验证实验中已证明了保形电沉积和电极可逆性，但在应用所需的更高容量（例如10 mA h/cm²）下实现高水平的可逆性正变得越来越具有挑战性。由导电多孔基材组成的非平面“三维”电极通常被认为可以克服可逆性和容量之间的权衡，因为它们假设在电子传导框架中“容纳”电沉积物，为电子流动提供冗余路径。在此，我们对这一假设提出质疑，转而表明具有适度电导率（理想情况下，电导类似于电解质的离子电导）且由面向阴极的钝化表面组成的非平面基材可有效调节电结晶。相比之下，具有高本征电导率或前表面有高导电涂层的结构会导致主要的面外生长，使三维结构实际上起到二维基材的作用。以锌为例，我们证明，前后分别涂覆SiO和Cu的相互连接的碳纤维基材成功地在宏观长度尺度上将电镀锌金属引入三维框架，最大限度地利用了框架的内部空间。将电沉积物有效整合到三维框架中还能在高电流密度（例如10 mA/cm²）和高面积容量（例如10 mA h/cm²）下实现前所未有的电镀/脱镀可逆性>99.5%。在严格N/P比为3:1的全电池Zn||NaVO电池中使用这些基材，还显示出可延长循环寿命。
