單晶高鎳陰極的動力學限制
作者：
小柯機器人發布時間：2020/11/25 13:15:23
美國布魯克海文國家實驗室Feng Wang團隊揭示了單晶高鎳陰極的動力學限制。 該研究成果發表在2020年11月20日出版的國際學術期刊《德國應用化學》。
高鎳陰極在提高鋰離子電池容量的同時降低成本方面引起了人們的極大興趣。為了克服多晶中的晶間裂紋問題，單晶被認為是一種很有吸引力的替代方案，但也加劇了人們對其離子傳輸和動力學性質的擔憂。
研究人員使用硬X射線顯微鏡/光譜對LiNi0.8Mn0.1Co0.8O2單晶中電化學反應的定量分析，揭示了氧化還原動力學對充電狀態（SOC）有很強的依賴性——氧化還原反應在低SOC下緩慢，而隨著體電極和單個粒子中SOC的增加而迅速增加。傳輸特性測試和有限元模擬證實了這一觀察結果，表明在低SOC下，單晶中的動力學限制受離子運輸的控制，並且可以通過與集成在同一電極中的多晶或小晶體的協同作用來緩解。
通過闡明單晶高鎳陰極動力學限制的機理起源和緩解方案，該項工作在實現其實際應用方面向前邁進了一步。
附：英文原文
Title: Kinetic Limitations in Single‐Crystal High‐Nickel Cathodes
Author: Feng Wang, Mingyuan Ge, Sungun Wi, Xiang Liu, Jianming Bai, Steven Ehrlich, Deyu Lu, Wah-Keat Lee, Zonghai Chen
Issue&Volume: 20 November 2020
Abstract: High‐nickel cathodes attract immense interest for use in lithium‐ion batteries, to boost Li‐storage capacity while reducing cost. For overcoming the intergranular‐cracking issue in polycrystals, single‐crystals are considered an appealing alternative, but aggravating concerns on compromising the electrochemical kinetics of electrodes. We report here a quantitative assessment of electrochemical reaction in single‐crystal LiNi0.8Mn0.1Co0.8O2 using operando hard X‐ray microscopy/spectroscopy, revealing a strong dependence of redox kinetics on the state of charge (SOC) ‐ being sluggish at low SOC while increasing rapidly as SOC increases both in the bulk electrode and individual particles. The observation is corroborated by transport measurements and finite‐element simulation, indicating that the sluggish kinetics in single‐crystals is governed by ionic transport at low SOC and may be alleviated through synergistic interaction with polycrystals integrated into a same electrode. With the elucidated mechanistic origin and alleviation solution of kinetic limitations in single‐crystal high‐Ni cathodes, this work constitutes a step forward in enabling their practical deployment.
DOI: 10.1002/anie.202012773
Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202012773