The present invention may improve the lifetime characteristics of a lithium secondary battery, and particularly, may provide a non-aqueous electrolyte solution or cathode including a phosphate-based compound which may exhibit stable and excellent lifetime characteristics at high temperature and high voltage regardless of the moisture content or the presence of a pressing process of the electrode.

A non-aqueous electrolyte primary battery of the present invention includes: a negative electrode; a positive electrode; a separator; and a non-aqueous electrolyte. The negative electrode contains metallic lithium or a lithium alloy. The positive electrode contains a manganese oxide or a lithium-containing manganese oxide with a lithium content of 3.5% by mass or less. The non-aqueous electrolyte contains a phosphoric acid compound or a boric acid compound having in its molecule a group represented by General Formula (1) below, and the content of the phosphoric acid compound or the boric acid compound in the non-aqueous electrolyte is 8% by mass or less:

##STR00001## where X is Si, Ge or Sn; R.sup.1, R.sup.2 and R.sup.3 independently represent an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; and some or all of hydrogen atoms may be substituted with a fluorine atom.

A lithium ion battery has a flat wound electrode assembly, a nonaqueous electrolyte, and a battery case. The nonaqueous electrolyte contains an electrically insulating inorganic aggregate and is formed of an impregnating electrolyte impregnated into the flat wound electrode assembly and a surplus electrolyte not impregnated into the flat wound electrode assembly. Letting the flat wound electrode assembly be divided into a planar region where the electrode surfaces are planar surfaces and a lower wound curved region which is positioned vertically downward from the planar region and where the electrode surfaces are curved, a boundary plane that includes the boundary between the planar region and the lower wound curved region, the inorganic aggregate amount M.sub.O included in a space which is below the boundary plane and the inorganic aggregate amount M.sub.I included in the impregnating electrolyte within the flat wound electrode assembly satisfy the relationship M.sub.O>M.sub.I.

A non-aqueous electrolytic solution comprising a non-aqueous solvent and an electrolyte, which further contains a combination of a nitrile compound and an SO group-containing compound (or a dinitrile compound) in an amount of 0.001 to 10 wt. % imparts improved cycle performance and storage property to a lithium battery, particularly a lithium secondary battery.

Disclosed is a process for one-step preparing electrolyte used for lithium-iron(II) disulfide batteries. The process includes the following steps of: adding iodine-containing precursors into an organic solvent in an inert atmosphere, homogeneously stirring, then adding lithium-containing precursors, stirring and reacting, separating solids to obtain an electrolyte used for lithium-iron(II) disulfide batteries. The process involves one-step synthesizing electrolyte used for lithium-iron(II) disulfide batteries. The whole procedures do not introduce water and have a lower cost. The lithium-iron(II) disulfide batteries prepared by using the electrolyte prepared by the process of the present invention have better properties.

Electrolyte compositions comprising novel fluorine-containing carboxylic acid ester solvents are described. The fluorine-containing carboxylic acid ester solvents are represented by the formula R.sup.1C(O)OR.sup.2, wherein R.sup.1 is CH.sub.3CH.sub.2 and R.sup.2 is CH.sub.2CHF.sub.2, R.sup.1 is CH.sub.3 and R.sup.2 is CH.sub.2CH.sub.2CHF.sub.2, R.sup.1 is CH.sub.3CH.sub.2 and R.sup.2 is CH.sub.2CH.sub.2CHF.sub.2, R.sup.1 is CHF.sub.2CH.sub.2CH.sub.2 and R.sup.2 is CH.sub.2CH.sub.3, or R.sup.1 is CHF.sub.2CH.sub.2 and R.sup.2 is CH.sub.2CH.sub.3.
The electrolyte compositions are useful in electrochemical cells, such as lithium ion batteries.

A non-aqueous electrolytic solution comprising a non-aqueous solvent and an electrolyte, which further contains a combination of a nitrile compound and an S=O group-containing compound (or a dinitrile compound) in an amount of 0.001 to 10 wt. % imparts improved cycle performance and storage property to a lithium battery, particularly a lithium secondary battery.

Provided are a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, the nonaqueous electrolytic solution containing from 0.001 to 5% by mass of 1,3-dioxane and further containing from 0.001 to 5% by mass of at least one selected from a specified phosphoric acid ester compound, a specified cyclic sulfonic acid ester compound, and a cyclic acid anhydride containing a side chain having allyl hydrogen; and an energy storage device using the same. This nonaqueous electrolytic solution is capable of improving electrochemical characteristics at high temperatures and further capable of not only improving a capacity retention rate after a high-temperature cycle test but also decreasing a rate of increase of an electrode thickness.

Disclosed is an additive for a non-aqueous electrolyte, which is a compound having a double bond and at least two cyano groups, the two cyano groups being in a trans-formation to the double bond. Also, a non-aqueous electrolyte comprising the additive and an electrochemical device comprising the non-aqueous electrolyte are also disclosed. Further, an electrode comprising the cyano group-containing compound and an electrochemical device comprising the electrode are disclosed.

An electrolyte additive for a lithium battery, an electrolyte including the electrolyte additive, and a lithium battery including the electrolyte additive are disclosed. The electrolyte additive for a lithium battery includes a sulfonylmethylisocyanide-based compound. The electrolyte additive including the sulfonylmethylisocyanide-based compound may form a protective layer having improved high-temperature stability on positive and negative electrodes of a lithium battery, thereby improving the safety of the lithium battery.