穩定鋰金屬電池用雙氟乙醯胺調節的梯度固體電解質界面和鋰離子溶劑化
作者:
小柯機器人發布時間:2020/12/16 16:01:51
湖南大學馬建民團隊揭示了穩定鋰金屬電池用雙氟乙醯胺調節的梯度固體電解質界面和鋰離子溶劑化。 該研究成果於2020年12月11日發表於國際頂尖學術期刊《德國應用化學》。
固體電解質界面相(SEI)的結構和組分對整個電池的性能有著極其重要的影響,這取決於所用電解質的配方。然而,從結構到構件控制高質量SEI的形成仍然是一個挑戰。
該文中,研究人員採用雙氟乙醯胺(BFA)作為電解質添加劑,用於構建梯度固體電解質界面(SEI)結構,該結構由具有C-F鍵的親石表面組成,可以均勻捕獲鋰離子,具有富LiF底層,可以引導鋰離子快速傳輸,最終實現均勻沉積鋰離子。BFA分子通過減少電解液中的游離溶劑來改變Li+的溶劑化結構,從而提高電解液的抗氧化性能,防止電解液在陰極表面的大量降解,從而獲得高含量LiF的優質陰極電解液界面(CEI)。
此外,當使用NCM622作為陰極時,Li | LiNi0.6Co0.2Mn0.2O2(NCM622)全電池顯示出良好的循環穩定性(在0.5mAcm2下200次循環後容量高達149mAhg‐1)和良好的速率容量(在5mAcm2的高電流密度下,容量為117mAhg‐1)。通過理論計算證明了設計的電解液添加劑有助於構建高質量SEI和CEI結構和成分。
附:英文原文
Title: Gradient Solid Electrolyte Interphase and Lithium ion Solvation Regulated by Bisfluoroacetamide for Stable Lithium Metal Batteries
Author: Jianmin Ma, Fang Li, Jian He, Jiandong Liu, Mingguang Wu, Yuyang Hou, Huaping Wang, Shihan Qi, Quanhui Liu, Jiawen Hu
Issue&Volume: 11 December 2020
Abstract: The structure and components of solid electrolyte interphase (SEI) are extremely important to influence the performance of full cells, which is determined by the formulation of electrolyte used. However, it is still challenging to control the formation of high‐quality SEI from structure to components. Herein, we designed bisfluoroacetamide (BFA) as the electrolyte additive for the construction of a gradient solid electrolyte interphase (SEI) structure that consists of a lithophilic surface with C‐F bonds to uniformly capture Li ions and a LiF‐rich bottom layer to guide the rapid transportation of Li ions, endowing the homogeneous deposition of Li ions. Moreover, the BFA molecule changes the Li + solvation structure by reducing free solvents in electrolyte to improve the antioxidant properties of electrolyte and prevent the extensive degradation of electrolyte on the cathode surface, which can make sure superior cathode electrolyte interphase (CEI) with high‐content LiF. In addition, the Li||LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) full cells show excellent cycling stability (a high capacity of 149 mA h g ‐1 after 200 cycles at 0.5 mA cm ‐2 ) and good rate capability (a capacity of 117 mA h g ‐1 at a high current density of 5 mA cm ‐2 ) when NCM622 was used as the cathode. This work demonstrates that the design of electrolyte additives is powerful to construct the structure and components of high‐quality SEI and CEI through theoretical calculations.
DOI: 10.1002/anie.202013993
Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202013993