Identifying Capacity Limitations in the Li/Oxygen Battery Using Experiments and Modeling
Identifying Capacity Limitations in the Li/Oxygen Battery Using Experiments and Modeling
复制标题
DOI：
10.1149/1.3527055
复制
发表时间：
2011-01-01
影响因子：
3.9
通讯作者：
Luntz, A. C.
中科院分区：
文献类型：
--
作者：
Albertus, Paul;Girishkumar, G.;Luntz, A. C.
假设锂氧电池为Li2O2，其理论比能量为11,400 Wh/kg Li，可以实现较高的实际比能量。为了帮助理解锂/氧电池的物理特性，我们提出了第一个基于物理的模型，该模型包含了主要的热力学、输运和动力学过程。通过使用从平面电极实验中获得的放电产物（使用碳酸盐溶剂时包括碳酸盐和氧化物）的电阻作为厚度的函数的经验拟合，我们获得了多孔电极实验和模拟之间的良好匹配。实验和模型表明，放电产物具有电阻性，其厚度限制在几十纳米，其在放电多孔电极中的体积分数限制在几个百分点。平面电极实验，孔堵塞是不可能的，显示钝化类似于多孔电极实验，并允许我们得出结论，电钝化是我们细胞中主要的容量限制机制。虽然在碳酸盐溶剂中，Li2O2不是主要的放电产物，但我们认为，如果Li2O2是放电产物，则该模型的含义（即放电产物的电钝化限制了容量）也适用，因为它是一种固有的电子绝缘体。(C) 2011电化学学会。[DOI:10.1149/1.3527055]版权所有。
The Li/oxygen battery may achieve a high practical specific energy as its theoretical specific energy is 11,400 Wh/kg Li assuming Li2O2 is the product. To help understand the physics of the Li/oxygen battery we present the first physics-based model that incorporates the major thermodynamic, transport, and kinetic processes. We obtain a good match between porous-electrode experiments and simulations by using an empirical fit to the resistance of the discharge products (which include carbonates and oxides when using carbonate solvents) as a function of thickness that is obtained from flat-electrode experiments. The experiments and model indicate that the discharge products are electronically resistive, limiting their thickness to tens of nanometers and their volume fraction in one of our discharged porous electrodes to a few percent. Flat-electrode experiments, where pore clogging is impossible, show passivation similar to porous-electrode experiments and allow us to conclude that electrical passivation is the dominant capacity-limiting mechanism in our cells. Although in carbonate solvents Li2O2 is not the dominant discharge product, we argue that the implications of this model, (i.e., electrical passivation by the discharge products limits the capacity) also apply if Li2O2 is the discharge product, as it is an intrinsic electronic insulator. (C) 2011 The Electrochemical Society. [DOI:10.1149/1.3527055] All rights reserved.