J. Saunier

Thin and flexible lithium-ion batteries: investigation of polymer electrolytes

Lithium-ion polymer batteries were investigated. These batteries used microporous PVdF filled by the liquid electrolyte as polymer electrolyte. It has been shown that the conductivity only depends on PVdF porosity, as the contribution of the swollen PVdF structure may be neglected. The loss in conductivity induced by the microporous PVdF is limited while the tortuosity is equal to 1. A shut down effect was demonstrated. Thin and flexible batteries based on this polymer electrolyte meet the specifications of GSM application.

Electrochemical and spectroscopic studies of polymethacrylonitrile based electrolytes

Abstract Polymethacrylontrile (PMAN)-based electrolytes were recently proposed as polymer matrix for ambient temperature applications. The living anionic polymerization of methacrylonitrile allowed PMAN–POE–PMAN triblock copolymers to be prepared from different starting PEGs. In order to appreciate the salt/polymer interactions, solvent-free polymer electrolytes were prepared by dissolution of lithium imide (LiTFSI) in PMAN homopolymer and copolymers. Despite the high T g of PMAN host polymer, conductivities as high as 10 −4 S cm −1 were obtained around 90°C. Infra-red spectroscopy allowed the nitrile/salt interaction to be characterized. In particular, PMAN solvation number was determined from the homopolymer complexes. The investigation on the triblock copolymer complexes allowed the solvating competition between nitrile and ether functions to be highlighted.

Electrochemical study of polymethacrylonitrile electrolytes comparative investigation of polynitriles electrochemical stability through model molecules. Part II

The replacement of polyacrylonitrile by polymethacrylonitrile is expected to provide an improvement of the electrochemical stability in reduction of the plasticized polymer electrolytes. In addition to the investigation on the polymer electrolyte, a comparative study of polymethacrylonitrile and polyacrylonitrile, performed through their respective model repeat unit, i.e. trimethylacetonitrile and isobutyronitrile confirms the stability improvement obtained by replacing polyacrylonitrile tertiary hydrogen by a methyl in polymethacrylonitrile.

Electrochemical study of polymethacrylonitrile electrolytes: Conductivity study of polymer/salt complexes and plasticized polymer electrolytes. Part I

In order to increase the stability in reduction with respect to polyacrylonitrile (PAN), polymethacrylonitrile (PMAN), is proposed as a matrix for plasticized polymer electrolytes, useable in lithium batteries. Highly concentrated complexes of lithium salt in PMAN homopolymer were prepared using lithium perchlorate, lithium triflate or lithium imide salts, ionic conductivities as well as spectroscopic data showing the solvating ability of PMAN. In order to prevent PMAN dissolution in usual liquid electrolytes, UV curing was carried out. Although, non-optimized, the resulting plasticized PMAN electrolytes exhibit appreciable conductivities.

Swollen Polymethacrylonitrile Urethane Networks for Lithium Batteries

Copolymers of methacrylonitrile are reported. Surprisingly, their curing through urethane cross-links acts as an internal plasticization. This cross-linking prevents any dissolution or leakage, up to 90°C, when the networks are swollen by liquid organic electrolytes. These provide high conductivities, and the increase in resistivity with respect to pure liquid electrolytes remains ≤2. The electrochemical investigation shows a clear improvement of stability in reduction as compared to polyacrylonitrile. The first evaluations of lithium insertion in graphite are encouraging.

PVdF-based polymers for lithium batteries

Publisher Summary This chapter focuses attention on attention polyvinylidene fluoride (PVdF)-based polymer electrolytes, in the frame of lithium batteries. It first provides an overview of the different options involving polymers as electrolyte components of lithium batteries. Electrolyte components of lithium batteries are discussed first including information on polymer electrolytes, set liquid electrolyte — separator vs. gelled polymer electrolytes and gelled polymer electrolyte. It provides information on the morphology of VdF polymers including VdF homopolymers, VdF copolymers, and crystallinity. The next section describes non-porous-gelled polymer electrolytes based on PVdF copolymers. Macroporous PVdF membranes are discussed next. The next section details the electrochemical behavior of VdF-based separators. Battery performances are discussed finally. The chapter concludes that PVdF-based copolymers would be useful in the production of large lithium-ion batteries intended for electric or hybrid vehicles where safety is a deciding criterion. It adds that polymer electrolytes should be designed to be used both in lithium batteries and in fuel cells, thus expanding the market and lowering the production costs.