arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2107.01289cond-mat.mtrl-sciphysics.chem-ph
收藏

CFx电池边缘传播放电机理--第一性原理与实验研究

Edge-Propagation Discharge Mechanism in CFx Batteries -- a First Principles and Experimental Study

Kevin Leung, Noah B. Schorr, Matthew Mayer, Timothy N. Lambert, Y. Shirley Meng, K. L. Harrison

摘要:

与锂阳极耦合的氟化石墨(CFx)阴极在原电池中产生最高的理论能量密度(>860 Wh/g)之一。在实践中,观察到的放电电压(~ 2.5V)显著低于热力学极限(> 4.5V),放电速率低,并且到目前为止Li/CFx仅用于原电池。理解原子长度尺度下的放电机制将提高CFx的实际能量密度、倍率性能和可再充电性。到目前为止,纯实验技术还没有确定正确的放电机制或解释放电电压。我们应用密度泛函理论计算证明,在部分放电的CFx的CF/C边界的锂插入的基础上的CFx边缘传播放电机制表现出的电压范围为2.5至2.9 V -取决于是否涉及溶剂分子。电压和溶剂依赖性同意我们的放电和恒电流间歇滴定技术测量。预测的放电动力学与CFx操作一致。最后,我们预测Li/CFx的可再充电性下的应用高电位,沿充电途径不同的放电。我们的工作代表了一个通用的,准动力学框架来理解转换阴极的放电,规避了广泛使用的相图方法,该方法很可能不适用于Li/CFx,因为在该系统中没有达到平衡条件。

英文摘要:

Graphite fluoride (CFx) cathodes coupled with lithium anodes yield one of the highest theoretical energy densities (>860 Wh/g) among primary batteries. In practice, the observed discharge voltage (~2.5 V) is significantly lower than thermodynamic limits (>4.5 V), the discharge rate is low, and so far Li/CFx has only been used in primary batteries. Understanding the discharge mechanism at atomic length scales will improve practical CFx energy density, rate capability, and rechargeability. So far, purely experimental techniques have not identified the correct discharge mechanism or explained the discharge voltage. We apply Density Functional Theory calculations to demonstrate that a CFx-edge propagation discharge mechanism based on lithium insertion at the CF/C boundary in partially discharged CFx exhibits a voltage range of 2.5 to 2.9 V -- depending on whether solvent molecules are involved. The voltages and solvent dependence agrees with our discharge and galvanostatic intermittent titration technique measurements. The predicted discharge kinetics are consistent with CFx operations. Finally, we predict Li/CFx rechargeability under the application of high potentials, along a charging pathway different from that of discharge. Our work represents a general, quasi-kinetic framework to understand the discharge of conversion cathodes, circumventing the widely used phase diagram approach which most likely does not apply to Li/CFx because equilibrium conditions are not attained in this system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑