Mechanical property-reinforced PEO/PVDF/LiClO4/SN blend all solid polymer electrolyte for lithium ion batteries

The use of all solid polymer electrolyte (ASPE) is an effective way to ensure the safety of lithium ion batteries, however, the low room-temperature conductivity and poor mechanical properties limit its application. The addition of succinonitrile (SN), a solid plasticizer, can improve the ionic conductivity of ASPEs, but the mechanical performance is inevitably sacrificed. To address this issue, a kind of ASPS with PEO/PVDF/LiClO4/SN blend is proposed in this work, which utilizes microporous PVDF film as a support layer. To prepare such membrane, PEO/PVDF/LiClO4/SN solution is uniformly dripped onto PVDF film surface under negative pressure, which in turn infiltrates in and partially dissolves the PVDF film, followed by self-assembly between PVDF within solution and PVDF film, and thus forming the dense membrane with excellent mechanical properties. Taking the sample with 15% LiClO4 and 15% PEO as an example, its maximum stress is 10 times higher than conventional PEO based membrane without PVDF supporting layer. Besides, the prepared ASPF. membrane shows superior ionic conductivity, thermal stability and electrochemical stability window, which in turn leads to good initial discharge capabilities in LiFePO4/ASPE/Li cells at ambient-temperature. (C) 2020 Elsevier B.V. All rights reserved.