An electrochemical cell including: a negative electrode including calcium and an alkali metal; a positive electrode including one or more elements selected from the group consisting of Al, Si, Zn, Ga, Ge, Cd, In, Sn, Sb, Hg, Tl, Pb, Bi, Te, Bi, Pb, Sb, Zn, Sn and Mg; and an electrolyte including a salt of calcium and a salt of the alkali metal. The electrolyte is configured to allow the cations of the calcium and alkali metal to be transferred from the negative electrode to the positive electrode during discharging and to be transferred from the positive electrode to the negative electrode during charging. The electrolyte exists as a liquid phase and one or both of the negative electrode and the positive electrode exists as liquid or partially liquid phases at operating temperatures of the electrochemical cell.

Molten lithium electrochemical cells are disclosed. A solid electrolyte separates a molten lithium metal or molten lithium metal alloy from a cathode. The molten lithium cells provide high Coulombic efficiency and energy efficiency at operating temperatures less than 600 C. The cells are useful for stationary energy storage in power grids.

A electrochemical storage device, referred to herein as a radical-ion battery, is described. The radical-ion battery includes an electrolyte, first free radicals, and second free radicals, wherein the first free radicals and the second free radicals are different chemical species. The radical-ion battery also includes a separator that allows select ions to pass therethrough, but separates the electrolyte from the second free radicals.

An intermediate temperature sodium-halogen secondary cell that includes a negative electrode compartment housing a negative, molten sodium-based electrode and a positive electrode compartment housing a current collector disposed in a highly conductive molten positive electrolyte. A sodium halide (NaX) positive electrode is disposed in a molten positive electrolyte comprising one or more AlX.sub.3 salts, wherein X may be the same or different halogen selected from Cl, Br, and I, wherein the ratio of NaX to AlX.sub.3 is greater than or equal to one. A sodium ion conductive solid electrolyte membrane separates the molten sodium negative electrode from the molten positive electrolyte. The secondary cell operates at a temperature in the range from about 80 C. to 210 C.

An interfacial additive layer for decreasing the interfacial resistance/impedance of a silicon based electrode-containing device such as, for example, an energy storage device or a micro-resistor, is disclosed. The interfacial additive layer, which is composed of a molten lithium containing salt, is formed between a silicon based electrode and a solid polymer electrolyte layer of the device. The presence of such an interfacial additive layer increases the ion and electron mobile dependent performances at the silicon based electrode interface due to significant decrease in the resistance/impedance that is observed at the respective interface as well as the impedance observed in the bulk of the device.

Provided herein are energy storage devices. In some cases, the energy storage devices are capable of being transported on a vehicle and storing a large amount of energy. An energy storage device is provided comprising at least one liquid metal electrode, an energy storage capacity of at least about 1 MWh and a response time less than or equal to about 100 milliseconds (ms).

The present invention provides a sodium-aluminum secondary cell. The cell includes a sodium metal negative electrode, a positive electrode compartment that includes an aluminum positive electrode disposed in a positive electrolyte mixture of NaAl.sub.2X.sub.7 and NaAlX.sub.4, where X is a halogen atom or mixture of different halogen atoms selected from chlorine, bromine, and iodine, and a sodium ion conductive electrolyte membrane that separates the negative electrode from the positive electrolyte. In such cases, the electrolyte membrane can include any suitable material, including, without limitation, a NaSICON-type membrane. Generally, when the cell functions, both the sodium negative electrode and the positive electrolyte are molten and in contact with the electrolyte membrane. Additionally, the cell is functional at an operating temperature between about 100 C. and about 200 C.

An electrolyte element (10) comprises a perforated sheet (11) of non-reactive metal such as an aluminium-bearing ferritic steel, and a non-permeable ceramic layer (16b) of sodium-ion-conducting ceramic bonded to one face of the perforated sheet (11) by a porous ceramic sub-layer (16a). The perforated sheet (11) may be of thickness in the range 50 m up to 500 m, and the thickness of the non-permeable ceramic layer (16b) may be no more than 50 m, for example 20 m or 10 m. Thus the electrolyte properties are provided by the non-permeable thin layer (16b) of ceramic, while mechanical strength is provided by the perforated sheet (11). The electrolyte element (10) may be used in a rechargeable molten sodium-metal halide cell, in particular a sodium/nickel chloride cell (20). It makes cells with increased power density possible.

Square section liquid metal batteries (LMBs) with a grid device to suppress instabilities of fluids. The LMBs include a shell, negative current collector, negative material, metallic nets/plates, grid device, electrolyte, positive material, rectangular holes on partitions of grid device, and positive current collector. The positive material, electrolyte, and negative material are filled in the shell and automatically stratified from bottom to top according to the density from large to small. The negative current collector is linked with negative material, and the positive current collector is linked with positive material. The grid device is composed of partitions which cross each other and pass through the negative material, the electrolyte vertically in sequence, and extend inside the positive material. There are rectangular holes opened on the grid device, and the vertical height of each rectangular hole is larger than the biggest displacement of electrolyte during charging and discharging processes.

According to one embodiment, a secondary battery includes a positive electrode, a negative electrode and a separator. The positive electrode includes a first electrolyte containing aluminum ions. The negative electrode is capable of allowing lithium ions to be inserted and extracted. The separator is disposed between the positive electrode and the negative electrode. The separator has lithium ion conductivity.