Huang An, Liu Haodong, Manor Ofer, Liu Ping, Friend James
Materials Science and Engineering Program and the Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
Materials Science and Engineering Program and the Department of Nanoengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
Adv Mater. 2020 Apr;32(14):e1907516. doi: 10.1002/adma.201907516. Epub 2020 Feb 18.
Both powerful and unstable, practical lithium metal batteries have remained a difficult challenge for over 50 years. With severe ion depletion gradients in the electrolyte during charging, they rapidly develop porosity, dendrites, and dead Li that cause poor performance and, all too often, spectacular failure. Remarkably, incorporating a small, 100 MHz surface acoustic wave device (SAW) solves this problem. Providing acoustic streaming electrolyte flow during charging, the device enables dense Li plating and avoids porosity and dendrites. SAW-integrated Li cells can operate up to 6 mA cm in a commercial carbonate-based electrolyte; omitting the SAW leads to short circuiting at 2 mA cm . The Li deposition is morphologically dendrite-free and close to theoretical density when cycling with the SAW. With a 245 µm thick Li anode in a full Li||LFP (LiFePO ) cell, introducing the SAW increases the uncycled Li from 145 to 225 µm, decreasing Li consumption from 41% to only 8%. A closed-form model is provided to explain the phenomena and serve as a design tool for integrating this chemistry-agnostic approach into batteries whatever the chemistry within.
实用型锂金属电池既强大又不稳定，50多年来一直是一项艰巨的挑战。充电过程中，电解质存在严重的离子耗尽梯度，导致电池迅速出现孔隙、枝晶和锂金属死区，进而性能不佳，而且往往会引发严重故障。值得注意的是，加入一个小型的100兆赫表面声波装置（SAW）就能解决这个问题。该装置在充电时能提供声流电解质流，实现密集的锂镀层，避免孔隙和枝晶的形成。集成SAW的锂电池在商用碳酸盐基电解质中可运行至6毫安/平方厘米；若不使用SAW，则在2毫安/平方厘米时就会短路。在使用SAW进行循环时，锂沉积在形态上无枝晶，且接近理论密度。在全Li||LFP（磷酸铁锂）电池中，采用245微米厚的锂阳极，引入SAW后，未循环的锂从145微米增加到225微米，锂消耗从41%降至仅8%。本文提供了一个封闭形式的模型来解释这些现象，并作为一种设计工具，将这种与化学性质无关的方法集成到任何化学体系的电池中。
