Zheng Jingxu, Yin Jiefu, Zhang Duhan, Li Gaojin, Bock David C, Tang Tian, Zhao Qing, Liu Xiaotun, Warren Alexander, Deng Yue, Jin Shuo, Marschilok Amy C, Takeuchi Esther S, Takeuchi Kenneth J, Rahn Christopher D, Archer Lynden A
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
Sci Adv. 2020 Jun 17;6(25):eabb1122. doi: 10.1126/sciadv.abb1122. eCollection 2020 Jun.
The propensity of metal anodes of contemporary interest (e.g., Li, Al, Na, and Zn) to form non-planar, dendritic morphologies during battery charging is a fundamental barrier to achievement of full reversibility. We experimentally investigate the origins of dendritic electrodeposition of Zn, Cu, and Li in a three-electrode electrochemical cell bounded at one end by a rotating disc electrode. We find that the classical picture of ion depletion-induced growth of dendrites is valid in dilute electrolytes but is essentially irrelevant in the concentrated (≥1 M) electrolytes typically used in rechargeable batteries. Using Zn as an example, we find that ion depletion at the mass transport limit may be overcome by spontaneous reorientation of Zn crystallites from orientations parallel to the electrode surface to dominantly homeotropic orientations, which appear to facilitate contact with cations outside the depletion layer. This chemotaxis-like process causes obvious texturing and increases the porosity of metal electrodeposits.
当代备受关注的金属阳极（如锂、铝、钠和锌）在电池充电过程中形成非平面树枝状形态的倾向是实现完全可逆性的一个基本障碍。我们在一个三电极电化学池中通过实验研究了锌、铜和锂树枝状电沉积的起源，该电化学池一端由旋转圆盘电极界定。我们发现，离子耗尽诱导树枝状生长的经典图景在稀电解质中是有效的，但在可充电电池通常使用的浓电解质（≥1 M）中基本不相关。以锌为例，我们发现，在传质极限下的离子耗尽可以通过锌微晶从平行于电极表面的取向自发重新定向到主要垂直取向来克服，这种垂直取向似乎有助于与耗尽层外的阳离子接触。这种类似趋化作用的过程会导致明显的织构化，并增加金属电沉积物的孔隙率。
