Aea Technology Inc.

United Kingdom Atomic Energy Authority

Nexeon Limited

Accentus Plc

Absl Power Solutions Ltd.

Sumitomo Chemical Company, Limited

Esam Kronfli

Neville John Mattingley

Christine Ruth Jarvis

Michael Jonathan Lain

Melanie J Loveridge

Alan Hooper

Robin J Neat

Keith V Lovell

An electrode for lithium ion recharged battery cell includes current collectors, a cathode layer, a separator and a cohesive anode mass. The cohesive anode mass includes silicon as an active material and a polymeric binder. The polymeric binder is a homo-polymer or copolymer of one or more monomers selected from the group consisting of acrylic acid, 3-butenoic acid, 2-methacrylic acid, 2-pentenoic acid, 2,3-dimethylacrylic acid, 3,3-dymethylacrylic acid, trans-butenedioc acid, cis-butenedioc acid and itaconic acid and optionally an alkali metal salt thereof. The silicon can include 20 to 100% of the active material in the cohesive mass. The binder is mixed with the silicon to form the cohesive mass that adheres to the current collector and maintains the cohesive mass in electrical contact with the current collector.

Binder for lithium ion rechargeable battery cells

A process for producing a porous polymeric structure which process comprises preparing a solution comprising a polymer which comprises vinylidene fluoride in a solvent/non-solvent mixture; holding the solution at an elevated temperature until the polymer is completely solvated; casting the solution to form a thin layer; and drying the thin layer to form a membrane. The polymer is dispersed in the non-solvent before addition of the solvent, when preparing the solution, to prevent microgel formation. The prolonged solvation at elevated temperature provides a stable solution, and enables membranes of controlled porosity to be formed.

Porous polymeric membrane comprising vinylidene fluoride

A method of making a cell component containing a polymer, the polymer consisting primarily of vinylidene fluoride, in which the polymer is mixed with at least one other ingredient, such as an organic plasticiser, and extruded at a temperature above its melting point. The method can be used to make electrolyte layers in which case the polymer would be mixed with at least a salt, and to make layers of composite material for use as anodes or cathodes, in which case the polymer would be mixed with at least a particulate insertion material. No solvents are required.

Extrusion of polymer-based cell components

A polymeric chain consisting primarily of vinylidene fluoride, onto which is grafted a mono-unsaturated carboxylic acid, ester, or amide, for example acrylic acid, may be combined with a lithium salt and a solvent to form an electrolyte material. This may be used as electrolyte in a lithium cell, or may be combined with an insertion material to make a composite electrode for such a cell. The electrolyte, and so also the composite electrode incorporating this electrolyte, adheres well to a metal current collector.

Organic electrolyte composition

A polymer electrolyte suitable for use in a lithium ion cell comprises polyvinylidene fluoride (PVdF) combined with a solution of a salt such as lithium perchlorate, in a compatible solvent such as an ethylene carbonate/N-methyl-pyrrolidone mixture. The PVdF is a homopolymer of high molecular weight, with a melt flow index at 230.degree. C. and 10 kg of less than 1.O g/10 min.

Polymer electrolyte

A solid polymer electrolyte is in the form of a gel comprising a complex of a solid polymer (e.g. poly(ethene oxide) and an alkali metal salt (e.g. LiClO.sub.4), the polymer being cross-linked to inhibit its transformation from an amorphous form to a crystalline form thereby to improve the alkali metal ion conductivity of the electrolyte at lower temperatures. The electrolyte may be made by irradiating (e.g. by gamma radiation or an electron beam) a solution, preferably aqueous, of the complex to cause the polymer to cross-link and form a gel. The electrolyte may be used as a component in a solid state electrochemical cell (e.g. for a rechargeable lithium battery), where the gel form of the electrolyte assists fabrication.

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Esam Kronfli