Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Hybridizing poly(vinylidene fluoride-co-hexafluoropropylene) with Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 as a lithium-ion electrolyte for solid state lithium metal batteries Juan Lu a,1 , Yanchen Liu a,1 , Penghui Yao a,1 , Zhiyu Ding a , Qiming Tang a , Junwei Wu a, ⁎ , Ziran Ye b , Kevin Huang c, ⁎ , Xingjun Liu a a Shenzhen Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China b Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310014, China c Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States HIGHLIGHTS • Garnet LLZTO electrolyte was compo- site with polymer PVDF-HFP electro- lyte. • Hybrid solid electrolyte exhibited good electrochemical performance. • The Li/LiFePO 4 cell showed superior cycling performance with virtually no capacity loss. GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Solid electrolyte Polymer Ceramic Ionic conductivity Capacity ABSTRACT Polymer/ceramic composite solid electrolyte is an appealing solution for the exploitation of flexible solid-state lithium-metal batteries. Here we report a solid-state Li-ion electrolyte composing of poly(vinylidene fluoride-co- hexafluoro propylene) (PVDF-HFP) polymer, ceramic powder Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO) and lithium salt LiTFSI. The composite electrolyte exhibits a high ionic conductivity of 8.80 × 10 -5 S·cm -1 at room tempera- ture. A coin battery with LiFePO 4 cathode is cycled under 0.5 C at room temperature for long cycles, achieving a Coulombic efficiency of 99.6% without virtually capacity loss (1st: 101.4 mAh·g -1 and 500th: 110.9 mAh·g -1 ). Such excellent performance can be ascribed to the formation of high ionic conductivity by LLZTO active garnet reducing polymer crystallinity. These results show that the developed polymer/ceramic composite has potential to be a high-performance electrolyte for solid-state lithium-metal batteries. 1. Introduction Attributed to the high voltage and long cycle life, rechargeable li- thium-ion batteries (LIBs) have become a primary and indispensable power source for our daily life [1–3]. However, the relatively low en- ergy density, high cost and concern on safety of commercial organic liquid electrolyte based LIBs are major barriers for the modern LIB technology to expand from thinner electronic products such as mobile https://doi.org/10.1016/j.cej.2019.02.148 Received 13 November 2018; Received in revised form 23 January 2019; Accepted 20 February 2019 ⁎ Corresponding authors. E-mail addresses: junwei.wu@hit.edu.cn (J. Wu), huang46@cec.sc.edu (K. Huang). 1 These authors are contributed equally to this work. Chemical Engineering Journal 367 (2019) 230–238 Available online 21 February 2019 1385-8947/ © 2019 Elsevier B.V. All rights reserved. T