Analysis Of Solid Polymer Electrolyte

Solid polymer electrolyte is gradually the research focus of lithium ion battery electrolyte. It can take into account the conductivity of traditional liquid electrolyte and the easy processing and easy forming characteristics of solid resin compound, which can effectively improve the electrochemical performance and safety performance of lithium ion. Solid polymer electrolytes are widely used in electronics, medical, space technology, electrochromism, optoelectronics, sensors, etc.

The study of solid polymer electrolytes began in 1973 with the discovery of the conductivity of polyethylene oxide (PEO) and alkali metal ion complexes by Wright et al. In 1979, French Armand reported that the PEO alkali metal salt complex has an ion conductivity of 10-5S / cm at 40-60 ℃, and has good film-forming properties, and can be used as a lithium ion battery electrolyte.

 The solid polymer electrolyte is composed of two parts, a polymer main body and a metal salt. The principle of conducting electricity is to introduce an inorganic salt with electrical conductivity into the traditional resin material. In the process of charging and discharging, the conductive ions in the inorganic salt achieve ion migration through the adsorption and analysis of the functional groups on the polymer chain.

In recent years, great progress has been made in the research of solid polymer electrolytes, and researchers have developed a variety of new solid polymer electrolytes. 

Professor Yi Cui from Stanford University ^[1] filled PEO / LiTFSI into a porous polyimide (PI) membrane with a thickness of only 8.6 μm, and designed an ultra-thin 8.6-micron-thick nanoporous “PI / PEO / LiTFSI "Structured solid electrolytes give the electrolyte better flexibility and safety, and provide new ideas for solving the problem of ultra-thin electrolyte membranes that are easy to short-circuit. All-solid-state lithium ion batteries assembled with this electrolyte have very good cycle stability and safety.

The team of Professor Fang Lian ^[2] of Beijing University of Science and Technology designed and synthesized a new type of "Salt-with-Salt" double lithium salt type flexible solid polymer electrolyte, using their boron-based single ion conductor polymer in polyvinyl acetal (PVFM) Based on the research accumulation of electrolyte (LiPVFM for short), high-concentration lithium salt (LiTFSI) is dissolved in LiPVFM matrix. The double lithium salt type solid electrolyte has significantly improved room temperature ion conductivity of 5.7 × 10-4 S cm-1, high lithium ion migration number of 0.79, excellent tensile strength and plastic deformation ability, and the performance of the solid metal lithium battery using the electrolyte Out of high security.

references:

1.Yi Cui, Jian Qin, etal.Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries.Nature Nanotechnology volume [J] .https: //www.nature.com/articles/s41565-019- 0465-3

2.Fang Lian *, Hong-yan Guan, Yan Wen, Xiao-rong Pan, Polyvinyl formal based single-ion conductor membranes as polymer electrolyte for lithium ion batteries, Journal of Membrane Science, 2014, 469: 67-72.