Hybrid electrodes for batteries are disclosed having a protective electrochemically active layer on a metal layer. Other hybrid electrodes include a silicon salt on a metal electrode. The protective layer can be formed directly from the reaction between the metal electrode and a metal salt in a pre-treatment solution and/or from a reaction of the metal salt added in an electrolyte so that the protective layer can be formed in situ during battery formation cycles.

Positive electrode active material particles that inhibit a decrease in capacity due to charge and discharge cycles are provided. A high-capacity secondary battery, a secondary battery with excellent charge and discharge characteristics, or a highly-safe or highly-reliable secondary battery is provided. A novel material, active material particles, and a storage device are provided. The positive electrode active material particle includes a first region and a second region in contact with the outside of the first region. The first region contains lithium, oxygen, and an element M that is one or more elements selected from cobalt, manganese, and nickel. The second region contains the element M, oxygen, magnesium, and fluorine. The atomic ratio of lithium to the element M (Li/M) measured by X-ray photoelectron spectroscopy is 0.5 or more and 0.85 or less. The atomic ratio of magnesium to the element M (Mg/M) is 0.2 or more and 0.5 or less.

An additive for a non-aqueous electrolyte solution that can suppress the initial gas generation amount when used in a non-aqueous electrolyte solution battery. The additive for a non-aqueous electrolyte solution is represented by any one of formulae [1] to [4]: ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, X.sup.1, X.sup.2 and Y are as defined in the specification.

This invention provides nonaqueous electrolyte solutions for lithium batteries. The nonaqueous electrolyte solutions comprise a liquid electrolyte medium; a lithium-containing salt; and at least one oxygen-containing brominated flame retardant.

This invention provides nonaqueous electrolyte solutions for lithium batteries which contain one or more brominated flame retardants. The nonaqueous electrolyte solutions comprise i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) at least one brominated flame retardant. The brominated flame retardant is present in the electrolyte solution in a flame retardant amount, has a boiling point of about 60° C. or higher, and has a bromine content of about 55 wt % or more based on the weight of the brominated flame retardant.

A secondary battery that can withstand at least high temperature is achieved by designing the structure of the secondary battery. The secondary battery uses: a positive electrode active material obtained by a formation method including a first step of forming a first mixture by pulverizing magnesium fluoride, lithium fluoride, a nickel source, and an aluminum source and then mixing the pulverized materials with powder of lithium cobalt oxide, and a second step of forming a second mixture by heating the first mixture at a temperature lower than an upper temperature limit of the lithium cobalt oxide; and an electrolyte solution to which LiBOB is added.

An electrolyte solution includes an electrolyte salt and an organic solvent, wherein the electrolyte salt includes lithium bis(fluorosulfonyl)imide (LiFSI), and the percentage mass content of the lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte solution is 4.5%-11%; the organic solvent includes ethylene carbonate, and the percentage mass contents of the ethylene carbonate and the lithium bis(fluorosulfonyl)imide satisfy: 0.9≤W.sub.LiFSI/(16.77%−W.sub.EC)≤2.9. The electrolyte solution of the present disclosure can make the battery take lower cell internal resistance, excellent high temperature storage performance and high temperature cycling performance into account at the same time.

The invention provides a method of recovering a lithium electrolyte salt from a used electrolyte, the method comprising: contacting a used electrolyte comprising a lithium electrolyte salt and electrolyte solvent with a polar aprotic solvent to produce a solution comprising the lithium electrolyte salt, the electrolyte solvent and the polar aprotic solvent, wherein at least one of the electrolyte solvent and the polar aprotic solvent comprises carbonate solvent, combining the solution with a precipitation solvent in which the lithium electrolyte salt is poorly soluble; precipitating a precipitated composition comprising the lithium electrolyte salt solvated by the carbonate solvent from a solvent mixture comprising the polar aprotic solvent, the precipitation solvent and the electrolyte solvent, wherein the precipitated composition precipitates as a solid or as a liquid; and separating the precipitated composition from the solvent mixture.

A fluid delivery system can include a spray gun. The spray gun can include a mix chamber assembly having at least two bores configured to receive a first fluid and a second fluid, and a chamber fluidly coupled to the at least two bores, the chamber configured to mix the first and the second fluid. The spray gun can include a handle and a winged extension disposed to contact at least a portion of an operator's back hand when the operator holds the spray gun via the handle.

Provided is a non-aqueous electrolyte solution that achieves a favorable balance between suppressing an increase in resistance and improving metallic Li precipitation resistance in an embodiment that contains LiPO.sub.2F.sub.2. The non-aqueous electrolyte solution disclosed here is used in a non-aqueous electrolyte secondary battery, and contains lithium difluorophosphate and a Cs cation-containing compound. When the total amount of the non-aqueous electrolyte solution is taken to be 100 mass %, the content of the lithium difluorophosphate is 1.0 mass % or less and the content of the Cs cation-containing compound is 0.1 to 0.5 mass %.