JP-2026076383-A - Non-aqueous secondary battery and non-aqueous electrolyte used therein

Abstract

[Problem] To provide a non-aqueous electrolyte that suppresses the voltage drop of a non-aqueous secondary battery due to the dissolution and extraction reaction of metals. [Solution] The non-aqueous electrolyte for a non-aqueous secondary battery comprises a non-aqueous solvent, an electrolyte salt, an isocyanate compound, and a nitrile compound having two or more nitrile groups, wherein the content of the isocyanate compound ( C₁NCO) is greater by mass than the content of the nitrile compound ( C₁CN) . [Selection Diagram] Figure 1

Inventors

• 佐藤 貴夫

Assignees

• パナソニックＩＰマネジメント株式会社

Dates

Publication Date

20260511

Application Date

20260224

Priority Date

20201028

Claims (11)

1. Non-aqueous solvents and Electrolyte salts, Isocyanate compounds and, A nitrile compound having two or more nitrile groups, A non-aqueous electrolyte for a non-aqueous secondary battery, wherein the isocyanate compound content C₁NCO is greater by mass than the nitrile compound content C₁CN .
2. The isocyanate compound content C NCO is 0.001% by mass or more and 5% by mass or less. The non-aqueous electrolyte for a non-aqueous secondary battery according to claim 1, wherein the content of the nitrile compound C CN is 0.001% by mass or more and 5% by mass or less.
3. The isocyanate compound content C NCO is less than 4% by mass. The non-aqueous electrolyte for a non-aqueous secondary battery according to claim 2, wherein the content of the nitrile compound C CN is less than 1.6% by mass.
4. A non-aqueous electrolyte for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the ratio of the isocyanate compound content C₁NCO₃ to the nitrile compound content C₂CN₃ ( C₁NCO₃ / C₂CN₃) is in the range of 70/30 to 99/1.
5. The isocyanate compound has two or more isocyanate groups, and is a non-aqueous electrolyte for a non-aqueous secondary battery according to any one of claims 1 to 4.
6. The non-aqueous electrolyte for a non-aqueous secondary battery according to claim 5, wherein the isocyanate compound is a diisocyanate compound.
7. The non-aqueous electrolyte for a non-aqueous secondary battery according to claim 5, wherein the diisocyanate compound comprises at least one selected from the group consisting of hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo[2.2.1]heptane-2,5-diirbis(methylisocyanate), bicyclo[2.2.1]heptane-2,6-diirbis(methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.
8. The non-aqueous electrolyte for a non-aqueous secondary battery according to any one of claims 1 to 7, wherein the nitrile compound is a dinitrile compound.
9. The non-aqueous electrolyte for a non-aqueous secondary battery according to claim 8, wherein the dinitrile compound comprises at least one selected from the group consisting of succinonitrile, glutalonitrile, adiponitrile, pimeronitrile, and suberonitrile.
10. The device comprises a positive electrode containing a positive electrode active material, a separator, a negative electrode facing the positive electrode via the separator, and a non-aqueous electrolyte. The non-aqueous electrolyte comprises a non-aqueous solvent, an electrolyte salt, an isocyanate compound, and a nitrile compound having two or more nitrile groups. A non-aqueous secondary battery wherein the non-aqueous electrolyte contains more of the isocyanate compound C₁NCO by mass than the nitrile compound C₁CN .
11. The positive electrode active material has a layered rock salt type structure and includes a lithium transition metal composite oxide comprising Ni and at least one selected from the group consisting of Co, Mn, and Al. The non-aqueous secondary battery according to claim 10, wherein the proportion of Ni among the metal elements other than Li contained in the lithium transition metal composite oxide is 80 atomic percent or more.

Description

This disclosure primarily relates to non-aqueous electrolytes for non-aqueous secondary batteries. Patent Document 1 proposes a non-aqueous electrolyte comprising a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent, characterized by comprising: (A) at least one compound selected from the group consisting of unsaturated carbonates and specific cyclic compounds; (B) a fluorine-containing ethylene carbonate derivative; and (C) a specific CN compound. Patent Document 2 proposes a non-aqueous electrolyte for lithium batteries, characterized in that the electrolyte is dissolved in a non-aqueous solvent, and the non-aqueous electrolyte further contains a nitrile compound and an S=O group-containing compound. Patent Document 3 proposes a non-aqueous electrolyte for a non-aqueous electrolyte battery equipped with a positive electrode and a negative electrode capable of intercalating and releasing metal ions, characterized in that the non-aqueous electrolyte, along with the electrolyte and a non-aqueous solvent, contains (A) a compound having at least two isocyanate groups in its molecule and a compound having at least two cyano groups in its molecule, and (B) the content ratio (mass ratio) of the compound having at least two isocyanate groups in its molecule to the compound having at least two cyano groups in its molecule is 50:50 to 1:99. Japanese Patent Publication No. 2013-51202Japanese Patent Publication No. 2004-179146Japanese Patent Publication No. 2013-65540 Non-aqueous secondary batteries, such as lithium-ion batteries, consist of a positive electrode, a negative electrode, and a non-aqueous electrolyte. When metals such as copper and iron are present in a non-aqueous secondary battery that utilizes electrochemical oxidation-reduction reactions, a metal leaching reaction occurs, causing a decrease in the voltage of the non-aqueous secondary battery. One aspect of this disclosure relates to a non-aqueous electrolyte for a non-aqueous secondary battery, comprising a non-aqueous solvent, an electrolyte salt, an isocyanate compound, and a nitrile compound having two or more nitrile groups, wherein the content of the isocyanate compound C₁NCO is greater by mass than the content of the nitrile compound C₁CN . Another aspect of this disclosure relates to a non-aqueous secondary battery comprising a positive electrode containing a positive electrode active material, a separator, a negative electrode facing the positive electrode via the separator, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises a non-aqueous solvent, an electrolyte salt, an isocyanate compound, and a nitrile compound having two or more nitrile groups, and in the non-aqueous electrolyte, the content of the isocyanate compound C₁NCO is greater by mass than the content of the nitrile compound C₂CN . According to this disclosure, it is possible to suppress the voltage drop of a non-aqueous secondary battery due to the dissolution and extraction reaction of metals. Figure 1 is a cutaway perspective view of a non-aqueous secondary battery according to one embodiment of the present disclosure. The non-aqueous electrolyte for non-aqueous secondary batteries according to this disclosure comprises a non-aqueous solvent, an electrolyte salt, an isocyanate compound, and a nitrile compound having two or more nitrile groups (hereinafter also referred to as "nitrile compound P"). However, the isocyanate compound content C₁NCO₃ is greater by mass than the nitrile compound P content C₁CN₂ ( C₁NCO₃ > C₁CN₂ ). Furthermore, the non-aqueous secondary battery according to this disclosure comprises a positive electrode containing a positive electrode active material, a separator, a negative electrode facing the positive electrode via the separator, and the non-aqueous electrolyte. When a metal is exposed to the positive electrode potential, metal ions may leach from the metal into the non-aqueous electrolyte. Metal ions may also leach from the positive electrode active material. For example, the positive electrode of a non-aqueous secondary battery contains a positive electrode active material, which has a high potential and contains metallic components (often transition metals). Metal ions leached into the non-aqueous electrolyte migrate from the positive electrode to the negative electrode and precipitate there. As such leaching reactions proceed, the voltage of the non-aqueous secondary battery decreases. Suppressing metal dissolution and precipitation is important in non-aqueous secondary batteries. In contrast, when the isocyanate compound content (mass%) and nitrile compound P content (mass%) in the non-aqueous electrolyte satisfy the condition C NCO > C CN , the metal dissolution reaction is significantly suppressed, and the decrease in battery voltage is suppressed. Adding isocyanate compounds or nitrile compounds P to a non-aqueous electrolyte alone can suppress the metal leaching reaction, but the effect of