There is a liquid electrolyte composition comprising: i) a magnesium salt comprising a trifluoromethane sulfonate anion; ii) an additive comprising an organic halide salt, an inorganic halide salt or a mixture thereof; and iii) a solvent comprising one or more ethers, wherein the organic halide salt comprises a halide anion and a cation selected from an optionally substituted quaternary ammonium or a three to nine membered N-heterocyclic cation, and the cation comprises at least one protonated nitrogen capable of dissociating the trifluoromethane sulfonate anion from the magnesium salt, and wherein the total concentration of cations of the inorganic halide salt and magnesium ions of the magnesium salt divided by the concentration of anions of the inorganic halide salt is greater than 1 in the electrolyte composition. There is further provided an electrochemical cell comprising a) a positive electrode; b) a magnesium negative electrode; and c) the electrolyte composition as described herein, wherein the positive electrode and the magnesium negative electrode are in fluid communication with the electrolyte.

Rechargeable batteries include a Ni.sub.yFe.sub.1-y cathode where 0≤y≤1, an anode comprising a current collector, a porous separator positioned between the cathode and the anode, and an electrolyte comprising MAlX.sub.4, wherein M is Na, Li, K, or a combination thereof, and X is Cl, Br, I, or a combination thereof, and wherein the electrolyte is a solid at temperatures less than 50° C. The batteries are temperature activated. The electrolyte temperature is increased above its melting point while charging and reduced below the melting point for energy storage, such as seasonal energy storage. The electrolyte temperature is increased above the melting point again to discharge the battery.

An electrolyte composition and a metal-ion battery employing the same are provided. The electrolyte composition includes a metal chloride, a chlorine-containing ionic liquid, and an additive, wherein the additive has a structure represented by Formula (I)

[M].sub.i[(A(SO.sub.2C.sub.xF.sub.2x+1).sub.y).sup.b−].sub.j  Formula (I) , wherein M can be imidazolium cation, ammonium cation, azaannulenium cation, . . . etc., wherein M has a valence of a; a can be 1, 2, or 3; A can be N, O, Si, or C; x can be 1, 2, 3, 4, 5, or 6; y can be 1, 2, or 3; b can be 1, 2, or 3; i can be 1, 2, or 3; j can be 1, 2, or 3; a/b=j/i; and when y is 2 or 3, the (SO.sub.2C.sub.xF.sub.2x+1) moieties are the same or different.

A thermal battery can include: an anode of lithium alloy; a metal-fluoride cathode having Ni; and an electrolyte composition in contact with the anode and cathode. A thermal battery can also include: an anode of lithium alloy; a metal-fluoride cathode having an oxide selected from V.sub.2O.sub.5 or LiVO.sub.3; and an electrolyte composition in contact with the anode and cathode. In one aspect, a metal of the metal fluoride cathode includes Ni, Fe, V, Cr, Mn, Co, or mixture thereof. In one aspect, the metal-fluoride cathode includes NiF.sub.2, FeF.sub.3, VF.sub.3, CrF.sub.3, MnF.sub.3, CoF.sub.3, or a mixture thereof. A method of providing electricity can include: providing an electronic device having a thermal battery with a metal-fluoride cathode having Ni and/or having an oxide selected from V.sub.2O.sub.5 or LiVO.sub.3; and discharging the thermal battery to provide electricity.

The present disclosure provides an energy storage device comprising at least one electrochemical cell comprising a negative current collector, a negative electrode in electrical communication with the negative current collector, an electrolyte in electrical communication with the negative electrode, a positive current collector, and a positive electrode in electrical communication with the positive current collector and electrolyte. The positive electrode comprises a material that is solid at the operating temperature of the energy storage device.

An aluminum-based cathode (positive electrode) for storage cells formed by deposition of a layer of aluminum metal on a porous conductive substrate. Storage cells and batteries having the cathode. The porous conducting substrate can be metal, conductive carbon or a refractory material, such as a metal boride or metal carbide. The aluminum-deposited porous substrate is in electrical contact with a cathode current collector and a suitable liquid catholyte. The cathode is, for example, combined with a molten alkali metal anode to form a storage cell. The alkali metal and the catholyte are molten or liquid at operating temperatures of the cell. Methods of storing energy and generating energy using cell having the aluminum-based cathode are provided.

A molten sodium-based battery comprises a robust, highly Na-ion conductive, zero-crossover separator and a fully inorganic, fully liquid, highly cyclable molten cathode that operates at low temperatures.

A positive electrode composition is presented. The composition includes granules that comprise an electroactive metal, an alkali metal halide, and a metal sulfide composition that is substantially-free of oxygen. A molar ratio of the electroactive metal to an amount of sulfur in the metal sulfide composition is between about 1.5:1 and about 50:1. The positive electrode composition is substantially free of iron oxide, iron sulfate, cobalt oxide and cobalt sulfate. An energy storage device and a related energy storage system are also described.

An electrochemical cell comprising: a negative electrode comprising lithium and aluminum; a positive electrode, separate from the negative electrode, comprising a liquid phase having zinc; a liquid electrolyte, disposed between the negative electrode and the positive electrode, comprising a salt of lithium and a salt of zinc; and a bipolar faradaic membrane, disposed between the negative electrode and the positive electrode, having a first surface facing the negative electrode and a second surface facing the positive electrode, the bipolar faradaic membrane configured to allow cations of lithium to pass through and configured to impede cations of zinc from transferring from the positive electrode to the negative electrode, the bipolar faradaic membrane at least partially formed from a material having an electronic conductivity sufficient to drive faradaic reactions at the second surface with the cations of the positive electrode.

A process for treating an electrochemical cell is presented. The process includes charging the electrochemical cell in a discharged state to at least 20 percent state-of-charge of an accessible capacity of the electrochemical cell at a first temperature to attain the electrochemical cell in a partial state-of-charge or a full state-of-charge and holding the electrochemical cell in the corresponding partial state-of-charge or full state-of-charge at a second temperature. The first temperature and the second temperature are higher than an operating temperature of the electrochemical cell.