Ordered mesogenic units-containing hyperbranched star liquid crystal all-solid-state polymer electrolyte for high-safety lithium-ion batteries

Functional liquid crystal polymers have attracted much attention as new all-solid-state polymer electrolytes due to their ability of orientation. In this paper, a hyperbranched star liquid crystal polymer (HSLCP) electrolyte for lithium-ion batteries (LIBs) is developed for the first time. This type of HSLCP bears a hyperbranched poly(glycidol) (HPG) as core, poly-e-caprolactone (PCL) and poly (4-cyanobiphenyl methylmethacrylate) ((LC)(x)) compose the block arms of the HSLCP. (LC)(x) segments, one part of the arms, are assisted to promote transmission of Li-ion via orientation and PCL segments are used to dissociate lithium salt and efficiently migrate charge carriers. The good self-standing all-solid-state polymer electrolyte film composed of HSLCP and lithium bis(trifluoromethanesulfonimide (LiTFSI) can be formed by solution casting method. It is demonstrated that such a HSLCP exhibits good thermal stability (368 degrees C), the HSLCP-based electrolyte shows high ionic conductivity (5.98 x 10(-5) S cm(-1) at 30 degrees C), outstanding ion transference number (0.63), and wide electrochemical window (5.12 V). In addition, LiFePO4/Li batteries employing the electrolyte deliver good cycling performance and rate capability. Simultaneously, the corresponding half-cell can still power a LED lamp at room temperature. Thus, this is a great progress for liquid crystal-based polymer electrolytes to be applied to high energy LIBs. (c) 2017 Elsevier Ltd. All rights reserved.