NOVELTY - A lithium-ion battery cell comprises an anode, a cathode, a lithium salt electrolyte in an organic solvent, or carrier and/or polymer, optionally a separator between the anode and the cathode that is porous to the lithium salt electrolyte, and 0.02-20 wt.% polyether functionalized polycarboxylic acid having a polycarboxylic acid portion and a polyether portion. The polycarboxylic acid portion is derived from polymerizing unsaturated monomers having one or more carboxylic acid group through the carbon to carbon unsaturation and having a molecular weight of 700-350,000 g/mole.    USE - Lithium-ion battery cell for use in a portable electronic device such as cell phone and laptop computer, and in electric, hybrid, and plug-in hybrid vehicles.    ADVANTAGE - The lithium-ion battery cell has improved properties such as energy density and cycle durability, and ensures stable cell internal electrical resistance after repeated charge and discharge cycles.    DETAILED DESCRIPTION - A lithium-ion battery cell comprises an anode, a cathode, a lithium salt electrolyte in an organic solvent, or carrier and/or polymer, optionally a separator between the anode and cathode that is porous to the lithium salt electrolyte, and 0.02-20 wt.% polyether functionalized polycarboxylic acid having a polycarboxylic acid portion and a polyether portion. The polycarboxylic acid portion is derived from polymerizing unsaturated monomers having one or more carboxylic acid group through the carbon to carbon unsaturation and having a molecular weight of 700-350,000 g/mole, where 5-75 mol.% of the carboxylic acid groups of the polycarboxylic acid are converted to ester, amide, or imide linkages from reaction of the carboxylic acid groups with hydroxyl or amine terminated polyethers containing 3-80 ether repeat units. The hydroxyl or amine terminated polyethers are used to form the polyether portion of the polyether functionalized polycarboxylic acid when reacted with carboxylic acid groups of the polycarboxylic acid, where the weight percent of the hydroxyl or amine terminated polyethers is based on the weight of the electrolyte. An INDEPENDENT CLAIM is also included for a method for making a lithium-ion battery, which involves forming an anode electrode optionally having a coating made from a paste and an optional solvent, a cathode electrode optionally having a coating made from a paste and an optional solvent, a lithium salt, in an organic solvent, or carrier and/or polymer, and optionally a separator between the anode and cathode that is porous to the lithium salt and solvent, carrier or polymer, where the separator is desirable when the lithium salt is not contained in a polymer or polymer gel, and a polyether functionalized polycarboxylic acid is added during dissolving in the organic solvent or carrier prior to cell fabrication, dissolving in the electrode (preferably the anode) coating solvent prior to electrode paste fabrication and/or dissolving in the electrode (preferably the anode) paste prior to electrode coating.