The nonaqueous electrolyte energy storage device according to an aspect of the present invention includes a negative electrode, a positive electrode, and a nonaqueous electrolyte, and in the nonaqueous electrolyte energy storage device, the negative electrode includes a negative active material layer containing lithium metal, the nonaqueous electrolyte contains a fluorinated cyclic carbonate, a chain carbonate, and a sulfur-based cyclic compound, and the content of the fluorinated cyclic carbonate in the entire solvent of the nonaqueous electrolyte exceeds 20% by volume.

A rechargeable calcium battery formed from a calcium metal anode, a cathode formed from a composite carbon/sulfur (C/S), a metal oxide, or a metal sulfide, and a multi-component electrolyte containing a mixture of different salts. The calcium anode is formed as a thin, pure calcium metal foil that is polished and combined with a copper collector for redox activity. The cathode may be formed from a carbon-sulfur (CS) composite or metal oxide/sulfide, such as CaM.sub.xO.sub.y or CaM.sub.xS.sub.y, or formed from binary and ternary metals, such as CaM1aM2bO.sub.y/S.sub.y and CaM.sub.1aM.sub.2bM.sub.3cO.sub.y/S.sub.y. The battery also includes a multi-component electrolyte including calcium salts, such as Ca(TSFI).sub.2, Ca(ClO.sub.4).sub.2, Ca(BF.sub.4).sub.2, and CaPF.sub.6, or the pairing of lithium, sodium and potassium salts with one of the anions, such as Ca(TFSI), NaPF.sub.6, and Li(TFSI).

Electrolytes and electrolyte additives for energy storage devices comprising benzoyl peroxide based compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte comprising at least two electrolyte co-solvents, wherein at least one electrolyte co-solvent comprises a benzoyl peroxide based compound.

This nonaqueous electrolyte secondary battery is provided with: an electrode body that comprises a positive electrode and a negative electrode; and a nonaqueous electrolyte solution that contains a nonaqueous solvent. The ratio of the capacity (Qn) of the negative electrode to the capacity (Qp) of the positive electrode, namely Qn/Qp is 1.4 or more; and the nonaqueous electrolyte solution contains, relative to the total volume of the nonaqueous solvent at 25° C., from 0.5% by volume to 10% by volume of methyl acetate and from 0.01 mole/L to 0.05 mole/L of lithium bisoxalato borate.

Provided is a high-capacity cell pack in which cell imbalance is eliminated, precipitation of a poorly soluble redox shuttle can be prevented, deterioration due to overcharging is suppressed, cell yield is improved, and charge/discharge cycling is stable. The cell pack according to the present invention is a cell pack comprising non-aqueous secondary cells each comprising a non-aqueous electrolyte solution containing an electrolyte salt and a non-aqueous solvent, a positive electrode, and a negative electrode, wherein the cell pack is configured with a module in which two or more of the non-aqueous secondary cells are connected in series or with two or more of the modules in parallel, or the cell pack is configured with a module in which two or more of the non-aqueous secondary cells are connected in parallel or with two or more of the modules in series; each of the non-aqueous secondary cells constituting the module has a ratio of maximum capacity (B) to minimum capacity (A) of 1.00<B/A<2.00; and the non-aqueous electrolyte solution contains a redox shuttle having a reversible redox potential at a greater electropositive potential than a positive electrode potential at full charge.

Some aspects of the invention are related to lithium batteries, and more specifically, to in-situ control of solid electrolyte interface for enhanced cycle performance in lithium metal batteries. In some embodiments, the electrochemical cell comprises a solid electrolyte interphase (SEI) layer that is rich in inorganic materials (e.g., LiF, Li.sub.2O, Li.sub.2CO.sub.3) and has various advantageous properties (e.g., improved anode stability, etc.). Some embodiments are directed to methods of electrical energy storage and use of an electrochemical cell. In some cases, the methods comprise applying anisotropic force and/or formation voltage to a cell and forming an inorganic rich SEI layer in-situ.

A lithium secondary battery includes: a positive electrode that includes a positive electrode active material including a compound represented by the following Formula (X) and a binder including a polyvinylidene fluoride having a weight average molecular weight of from 300,000 to 950,000; a negative electrode; and a non-aqueous electrolytic solution that includes at least one of lithium difluorophosphate or lithium monofluorophosphate. In Formula (X), each of a, b, and c is independently more than 0 but less than 1.00, and the sum of a, b, and c is from 0.99 to 1.00.

LiNi.sub.aMn.sub.bCo.sub.cO.sub.2  (X)

Electrolytes and electrolyte additives for energy storage devices comprising dihydrofuranone based compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte comprising at least two electrolyte co-solvents, wherein at least one electrolyte co-solvent comprises a dihydrofuranone based compound.

An electric device that has excellent cycle durability includes: a positive electrode which includes a positive electrode active material layer containing a lithium nickel-based composite oxide and a spinel crystal-type lithium manganese composite oxide; and an electrolyte which contains a compound having an S═O bond in a molecule, in which a content ratio of the lithium nickel-based composite oxide in the positive electrode active material layer is 50% by mass or more with respect to the total mass of the lithium nickel-based composite oxide and the spinel crystal-type lithium manganese composite oxide, and a concentration of the compound having an S═O bond in a molecule in the electrolyte is 0.4 to 2.0% by mass.

An additive for an electrolyte solution improves the electrochemical properties of a lithium secondary battery.