Abstract: The invention provides a rechargeable electrochemical cell comprising a cell housing 10 divided by a separator 20 into a pair of electrode compartments, one of which contains an anode substance and the other of which contains an active cathode substance and an electrolyte. The anode and electrolyte are liquid at the operating temperature of the cell and the electrode compartments are each divided into a gas chamber communicating with an electrode chamber. The gas chamber contains an inert gas under pressure and the electrode chamber contains a liquid, namely the anode material or the liquid electrolyte. A wall of each electrode chamber is provided by the separator and each electrode chamber has a closeable bleed outlet 74, 80.

Abstract: The invention provides a method of protecting an electrochemical cell which has a molten sodium anode, a chloride-ion containing sodium aluminum halide molten salt electrolyte, an iron-containing cathode in contact with the electrolyte and a solid conductor of sodium ions which separates the anode from the electrolyte, from the adverse effects of overcharging. The method comprises operating the cell, to prevent oxidation of iron to FeCl.sub.3 in the cathode, by connecting it in parallel with a protective cell having an open circuit charging plateau at a voltage less than the open circuit voltage of the Fe/FeCl.sub.3 //Na plateau of the cell being protected, and greater than the open circuit voltage, in its fully charged state, of the cell being protected. The invention also provides a cell of this type protected in this fashion, a battery including one or more such protected cells, and a cathode for such cells.

Abstract: The invention relates to a rechargeable high temperature electrochemical cell having a molten sodium anode, a molten halide salt liquid electrolyte, a compatible cathode in contact with the liquid electrolyte, and a beta-alumina solid electrolyte between the anode and liquid electrolyte and isolating them from each other. The liquid electrolyte is non-acidic and contains sodium cations as its only alkali metal cations, aluminum cations and chloride anions and is doped with fluoride anions to combat progressively increasing internal resistance of the cell associated with cyclic charging and discharging thereof.

Abstract: The invention provides a method of protecting an electrochemical cell which has a molten sodium anode, a chloride-ion containing sodium aluminum halide molten salt electrolyte, an iron-containing cathode in contact with the electrolyte and a solid conductor of sodium ions which separates the anode from the electrolyte, from the adverse effects of overcharging. The method comprises operating the cell, to prevent oxidation of iron to FeCl.sub.3 in the cathode, by connecting it in parallel with a protective cell having an open circuit charging plateau at a voltage less than the open circuit voltage of the Fe/FeCl.sub.3 //Na plateau of the cell being protected, and greater than the open circuit voltage, in its fully charged state, of the cell being protected. The invention also provides a cell of this type protected in this fashion, a battery including one or more such protected cells, and a cathode for such cells.

Abstract: An electrochemical cell is provided with a molten sodium anode and a molten sodium aluminium halide salt electrolyte. The cathode comprises FeCl.sub.2, NiCl.sub.2, CoCl.sub.2 or CrCl.sub.2 as active cathode substance dispersed in an electronically conductive electrolyte-permeable matrix which is impregnated by the electrolyte. Between the anode and the electrolyte, and isolating them from each other, is a solid conductor of sodium ions or a micromolecular sieve which contains sodium sorbed therein. The proportions of sodium and aluminium ions in the electrolyte are selected so that the solubility of the active cathode substance in the electrolyte is at or near its minimum.

Abstract: The invention provides an electrochemical cell and an anode structure for an electrochemical cell. The anode structure comprises a substantially non-electronically conductive micromolecular sieve carrier wherein electrochemically active anode material in the form of an electronically conductive electropositive substance is sorbed and held in dispersed form, and a reservoir or source of the electropositive substance in contact with the carrier. The electropositive substance is liquid at the operating temperature of the cell.

Abstract: A method of making a cathode for a secondary electrochemical cell is disclosed. The method involves activating or preconditioning an oxide which has a spinel-type or oxo-spinel type structure of the formula AB.sub.2 O.sub.4 with at least one of A or B being a transition metal, and A and B being di-, tri-, or tetravalent cations selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg and Al. The method provides a cathode, which is in the form of a stable three-dimensional framework structure. In a secondary electrochemical cell the structure of the cathode is capable of reversible charge/discharge reactions while being stable with regard to other physical or chemical changes in structure.

Abstract: A cathode for an electrochemical cell is disclosed, and a cell including it, together with an active cathode current collector for use in an electrochemical cell and methods of forming such a cathode.The cathode in its discharged state comprises an intermediate refractory hard metal compound of at least one metal selected from:chromium, iron, manganese, cobalt and nickelwith at least one non-metal selected from:carbon, boron, nitrogen, silicon and phosphorous.The cathode is halogenated in its charged state.To form the cathode, the intermediate refractory hard metal is formed and then activated to make it capable of reacting electrochemically with halide ions in use in a cell.The active cathode current collector comprises a core of electroconductive material protected by said intermediate refractory hard metal compound as a surface layer thereon, activated to react electrochemically with halide ions in a cell.

Abstract: An electrolyte for use in an electrochemical cell is disclosed of the alkali metal-aluminium-halide type. The electrolyte has a melting point below 140.degree. C. at atmospheric pressure and conforms with the stoichiometric productMAlX.sub.4whereinM represents lithium cations, a mixture of lithium and potassium cations or a mixture of sodium and potassium cations; andX represents a mixture of chloride and fluoride anions.A method of reducing the melting point of a sodium-aluminium-chloride or lithium-aluminium-chloride electrolyte by doping it with a potassium fluoride, sodium fluoride, or lithium fluoride, to obtain said electrolyte with a melting point below 140.degree. C. is disclosed, as are various electrochemical cells employing the product electrolyte.

Abstract: An electrode for an electrochemical cell, the electrode comprising an electrochemically active substance selected from:(a) the group comprising or including the halogens, the alkali metals, the alkaline earth metals the first and second series of transition elements, lead, phosphorus, arsenic, antimony, bismuth, and aluminium;(b) an oxygen, sulphur or selenium composition; or(c) a composition containing carbon, baron, silicon or nitrogen with any of the substances of (a) or (b);and a zeolite molecular sieve carrier wherein the electrochemically active substance is sorbed and is held in dispersed form for effective use in a cell. An electrochemical cell including a pair of electrodes and an electrolyte, at least one electrode comprising an electrode as defined above.

Abstract: An electrochemical cell and an anode for use in an electrochemical cell are disclosed. The cell in its charged state comprises an anode, a cathode and an electrolyte. The anode comprises a polysulphide or a polyselenide of an alkali metal such as sodium, potassium, or lithium sorbed into a zeolite molecular sieve carrier.

Abstract: An electrochemical cell comprising an anode, a cathode and a solid electrolyte, and a battery made up of a plurality of such cells. The anode comprises silver or copper or alloys or amalgams thereof. The cathode is a molecular sieve carrier having a pore size of less than 1 micron and having a halogen, a chalcogen or phosphorous sorbed therein. The electrolyte is a multiple salt system having a silver or copper halogenide as a component thereof.

Abstract: A cathode for a high temperature cell, the cathode comprising an electronegative element selected from the group consisting of sulphur and selenium, and a molecular sieve carrier wherein the electronegative element is sorbed and wherein the electronegative element is held captive during use of the cathode in a cell. The molecular sieve carrier conveniently comprises dehydrated zeolite crystals. A high temperature cell comprising a cathode as described, a lithium alloy anode and an electrolyte comprising an eutectic mixture of potassium iodide-lithium iodide, or potassium chloride-lithium chloride.