Vol.:(0123456789) 1 3 Advanced Fiber Materials https://doi.org/10.1007/s42765-019-00006-x RESEARCH ARTICLE High‑Performance 3‑D Fiber Network Composite Electrolyte Enabled with Li‑Ion Conducting Nanofbers and Amorphous PEO‑Based Cross‑Linked Polymer for Ambient All‑Solid‑State Lithium‑Metal Batteries Chaoyi Yan 1  · Pei Zhu 1  · Hao Jia 1  · Jiadeng Zhu 1  · R. Kalai Selvan 1  · Ya Li 1  · Xia Dong 1  · Zhuang Du 1  · Indunil Angunawela 2  · Nianqiang Wu 3  · Mahmut Dirican 1  · Xiangwu Zhang 1 Received: 1 January 2019 / Accepted: 22 April 2019 © Donghua University, Shanghai, China 2019 Abstract Solid electrolytes have gained attention recently for the development of next-generation Li-ion batteries since they can fun- damentally improve the battery stability and safety. Among various types of solid electrolytes, composite solid electrolytes (CSEs) exhibit both high ionic conductivity and excellent interfacial contact with the electrodes. Incorporating active nanofb- ers into the polymer matrix demonstrates an efective method to fabricate CSEs. However, current CSEs based on traditional poly(ethylene oxide) (PEO) polymer sufer from the poor ionic conductivity of PEO and agglomeration efect of inorganic fllers at high concentrations, which limit further improvements in Li + conductivity and electrochemical stability. Herein, we synthesize a novel PEO based cross-linked polymer (CLP) as the polymer matrix with naturally amorphous structure and high room-temperature ionic conductivity of 2.40 × 10 −4  S cm −1 . Li 0.3 La 0.557 TiO 3 (LLTO) nanofbers are incorporated into the CLP matrix to form composite solid electrolytes, achieving enhanced ionic conductivity without showing fller agglomeration. The high content of Li-conductive nanofbers improves the mechanical strength, ensures the conductive network, and increases the total Li + conductivity to 3.31 × 10 −4  S cm −1 . The all-solid-state Li|LiFePO4 batteries with LLTO nanofber-incorporated CSEs are able to deliver attractive specifc capacity of 147 mAh g −1 at room temperature, and no evident dendrite is found at the anode/electrolyte interface after 100 cycles. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42765-019-00006-x) contains supplementary material, which is available to authorized users. * Mahmut Dirican mdirican@ncsu.edu * Xiangwu Zhang xzhang13@ncsu.edu 1 Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, Wilson College of Textiles, North Carolina State University, Raleigh, NC 27695-8301, USA 2 Department of Physics and Organic and Carbon Electronics Lab, North Carolina State University, Raleigh, NC 27695-8301, USA 3 Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506, USA