A Sandwich PVDF/HEC/PVDF Gel Polymer Electrolyte for Lithium Ion Battery. (10th August 2017)

• Record Type: Journal Article
• Authors: Zhang, M.Y.; Li, M.X.; Chang, Z.; Wang, Y.F.; Gao, J.; Zhu, Y.S.; Wu, Y.P.; Huang, W.
• Is Part Of: Electrochimica acta. Volume 245(2017)
• Page Start: 752
• Page End: 759
• Publication Date: 2017-08-10
• Subjects: Lithium ion battery -- Polymer electrolyte -- PVDF -- Cellulose -- Safety; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.05.154
• Languages: English
• ISSNs: 0013-4686

Abstract

Graphical abstract: TOC: A composite gel polymer electrolyte based on hydroxyethyl cellulose (HEC) and poly (vinylidene fluoride) (PVDF) with sandwich-like architecture exhibiting high safety, good mechanical property is prepared and characterized. Highlights: A new composite HEC-PVDF gel polymer electrolyte with sandwich-like structure is prepared. Its mechanical strength is largely improved compared with that of hydroxyethyl cellulose. Its ionic conductivity and lithium ion transference number are greatly increased. Li//LiFePO4 cell based this gel polymer electrolyte exhibits excellent performance. Abstract: A sandwich structure-like PVDF/HEC/PVDF polymer membrane is reported as host for matrix of gel polymer electrolytes for lithium ion batteries. The inner HEC (hydroxyethyl cellulose) layer is compact, and can avoid micro short-circuits. The producibility of the composite membrane is guaranteed due to the simple and efficient electro-spinning process for manufacturing the PVDF (poly(vinylidene fluoride)) layer and low-cost and eco-friendly HEC layer. This structure integrates the advantages of the HEC and PVDF, and it presents high uptake of liquid electrolyte (135.4%), excellent retention of liquid electrolyte, high ionic conductivity (0.88 mS cm −1 at ambient temperature), low activation energy for lithium movement (0.016 eV), and high lithium ion transference number ( t + = 0.57), all properties are superior to those of the pure HEC membrane and commercial polyolefin separator (Celgard 2730). With the PVDF/HEC/PVDF gel polymer electrolyte as the electrolyte and separator, the assembled Li//LiFePO4 cell exhibits a notably high discharge capacity (140 mAh g −1 ) over 140 cycles. The PVDF and HEC components are non-combustible, which is in sharp contrast with the combustible polymers for the commercial separators. These results show that this kind of sandwiched gel polymer electrolyte is promising for scale-up of lithium ion batteries especially those needing high safety and reliability.