Bridging Li7La3Zr2O12 Nanofibers with Poly(ethylene oxide) by Coordination Bonds to Enhance the Cycling Stability of All-Solid-State Lithium Metal Batteries

Xuewen Zheng; Jianghai Wei; Weiteng Lin; Kemeng Ji; Chengyang Wang; Mingming Chen

doi:10.1021/acsami.1c21131

Bridging Li₇La₃Zr₂O₁₂ Nanofibers with Poly(ethylene oxide) by Coordination Bonds to Enhance the Cycling Stability of All-Solid-State Lithium Metal Batteries

ACS Appl Mater Interfaces. 2022 Feb 2;14(4):5346-5354. doi: 10.1021/acsami.1c21131. Epub 2022 Jan 19.

Authors

Xuewen Zheng^{1

2}, Jianghai Wei^{1

2}, Weiteng Lin^{1

2}, Kemeng Ji^{1

2}, Chengyang Wang^{1

2}, Mingming Chen^{1

2}

Affiliations

¹ Key Laboratory for Green Chemical Technology of MOE, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China.
² Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, P. R. China.

PMID: 35044148
DOI: 10.1021/acsami.1c21131

Abstract

A solid-state composite polymer electrolyte comprising Li₇La₃Zr₂O₁₂ nanofibers (LLZO NFs) as fillers has the advantages of flexibility, ease of processing, and being low cost, thus being considered to be a promising electrolyte material for use in the next generation of highly safe lithium metal batteries. However, poor compatibility of organic parts and inorganic materials leads to quick capacity decay after long-term charge/discharging running because of inorganic/organic interface deterioration and thus, the related ineffective lithium-ion (Li⁺) conduction. Herein, a "Boston ivy-style" method is proposed to prepare a solid ceramic/polymer hybrid electrolyte that exhibits a dense interface structure. After grafting on Dynasylan IMEO (DI), the modified LLZO NFs are used as ligands to bond with coordinatively unsaturated metal centers of Ca²⁺. Furthermore, these Ca²⁺ bridge the modified LLZO NFs with poly(ethylene oxide) (PEO) via the ether oxygen atoms they possess. The bridges built between the two phases, PEO and LLZO NFs, are effective to interface strengthening and guarantee rapid Li⁺ conduction even after 900 cycles. The PEO/LLZO NFs-DI-Ca²⁺/LiTFSI electrolyte shows a high Li⁺ transference number of 0.72 (60 °C). The Li||LiFePO₄ cell delivers excellent cycling stability (capacity retention of 70.8% after 900 cycles, 0.5 C) and rate performance. The bridge strategy is proved to be effective and probably a promotion to the application of ceramic polymer-based solid-state electrolytes.

Keywords: Li7La3Zr2O12 nanofiber; all-solid-state lithium metal battery; composite electrolyte; interface; ionic conductivity.