Manufacturing method of lithium secondary battery

Patent metadata

Field	Value
Publication number	US-2016254572-A1
Application number	US-201514908883-A
Country	US
Kind code	A1
Filing date	Sep 10, 2015
Priority date	Sep 30, 2014
Publication date	Sep 1, 2016
Grant date	—

Abstract

Provided is a method of preparing a lithium secondary battery which may simultaneously improve output characteristics and lifetime characteristics of the lithium secondary battery by preparing an electrode on which an SEI film is formed through a pretreatment process, putting an electrode assembly including the electrode in a battery case, and injecting an electrolyte thereinto.

First claim

1 . A method of preparing a lithium secondary battery, the method comprising:
performing a pretreatment in which an SEI (solid electrolyte interphase) film is formed on an electrode by impregnating the electrode in a composition for forming an SEI film and applying a voltage to the electrode; and preparing an electrode assembly using the electrode having the SEI film formed thereon, putting the electrode assembly in a battery case, and performing a combination process of electrolyte injection and charging one or more times, wherein the composition for forming an SEI film comprises a lithium salt, a non-aqueous organic solvent, and an SEI film-forming agent forming the SEI film by an electrochemical oxidation or reduction decomposition reaction.

2 . The method of claim 1 , wherein the SEI film-forming agent comprises one selected from the group consisting of a cyclic carbonate-based compound containing an unsaturated bond; a cyclic or chain carbonate-based compound containing a halogen atom; a lithium salt containing an oxalato complex as an anion; an imide-based lithium salt; a fluorophosphate-based lithium salt; a 6-membered aromatic heterocyclic compound containing at least two nitrogen atoms in a molecule; and a sultone-based compound, or a mixture of two or more thereof.

3 . (canceled)

4 . The method of claim 1 , wherein the SEI film-forming agent is included in an amount of 0.1 wt % to 10 wt % based on a total weight of the composition for forming an SEI film.

5 . (canceled)

6 . The method of claim 1 , wherein the forming of the SEI film is performed by applying a voltage of 0.005 V to 4.5 V at a constant current of 0.01 C to 5 C.

7 . (canceled)

8 . (canceled)

9 . (canceled)

10 . The method of claim 1 , wherein the combination process of electrolyte injection and charging comprises:
a first injection step of preparing a battery cell by injecting a first electrolyte into the battery case; and a first charging step of charging the battery cell.

11 . The method of claim 1 , wherein the combination process of electrolyte injection and charging comprises:
a first injection step of preparing a battery cell by injecting a first electrolyte into a battery case; a first charging step of charging the battery cell; a second injection step of injecting a second electrolyte into the charged battery cell; and a second charging step of charging the battery cell into which the second electrolyte is injected.

12 . The method of claim 10 , wherein the first electrolyte comprises at least one lithium salt selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiBF 4 , LiBF 6 , LiSbF 6 , and LiSO 3 CF 3 ,
the electrode comprises an aluminum current collector, and an AlF 3 film is formed on the current collector after the first charging step.

13 . The method of claim 10 , wherein the first electrolyte further comprises a sulfonic acid ester-based additive.

14 . (canceled)

15 . The method of claim 11 , wherein the second electrolyte comprises an imide-based lithium salt.

16 . (canceled)

17 . (canceled)

18 . The method of claim 10 , wherein the first charging step is performed by applying a voltage of 1.0 V to 4.5 Vat a constant current of 0.01 C to 5 C.

19 . (canceled)

20 . The method of claim 11 , wherein the second charging step is performed by applying a voltage of 2.0 V to 4.5 V at a constant current of 0.01 C to 5 C in a state in which the battery case is sealed after the injection of the second electrolyte.

21 . (canceled)

22 . The method of claim 10 , wherein the SEI film-forming agent comprises a cyclic carbonate-based compound containing an unsaturated bond, and
the first electrolyte comprises at least one lithium salt selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiBF 4 , LiBF 6 , LiSbF 6 , and LiSO 3 CF 3 .

23 . The method of claim 22 , wherein the first electrolyte further comprises a sulfonic acid ester-based additive.

24 . The method of claim 11 , wherein the SEI film-forming agent comprises a cyclic carbonate-based compound containing an unsaturated bond,
the first electrolyte comprises at least one lithium salt selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiBF 4 , LiBF 6 , LiSbF 6 , and LiSO 3 CF 3 ; and a sulfonic acid ester-based additive, and the second electrolyte comprises an imide-based lithium salt.

25 . (canceled)

26 . (canceled)

27 . A lithium secondary battery prepared by the method of claim 1 .

28 . The lithium secondary battery of claim 27 , comprising an electrode in which an SEI film-forming agent derived SEI film on a surface of the electrode and at least one layer of film formed by an electrochemical oxidation or reduction reaction of an electrolyte on the SEI film are formed,
wherein the SEI film-forming agent comprises one selected from the group consisting of a cyclic carbonate-based compound containing an unsaturated bond; a cyclic or chain carbonate-based compound containing a halogen atom; a lithium salt containing an oxalato complex as an anion; an imide-based lithium salt; a fluorophosphate-based lithium salt; a 6-membered aromatic heterocyclic compound containing at least two nitrogen atoms in a molecule; and a sultone-based compound, or a mixture of two or more thereof.

29 . The lithium secondary battery of claim 27 , comprising an electrode in which an SEI film derived from a cyclic carbonate-based compound containing an unsaturated bond on a surface of the electrode and a sulfonic acid ester-based additive derived film on the SEI film are formed.

30 . The lithium secondary battery of claim 27 , comprising an electrode in which an SEI film derived from a cyclic carbonate-based compound containing an unsaturated bond on a surface of the electrode, a sulfonic acid ester-based additive derived film on the SEI film, and an imide-based lithium salt derived film on the sulfonic acid ester-based additive derived film are formed.

31 . A battery module comprising the lithium secondary battery of claim 27 as a unit cell.

32 . A battery pack comprising the battery module of claim 31 .

33 . (canceled)

34 . (canceled)

35 . The method of claim 11 , wherein the first electrolyte comprises at least one lithium salt selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiBF 4 , LiBF 6 , LiSbF 6 , and LiSO 3 CF 3 ,
the electrode comprises an aluminum current collector, and an AlF 3 film is formed on the current collector after the first charging step.

36 . The method of claim 11 , wherein the first electrolyte further comprises a sulfonic acid ester-based additive.

37 . The method of claim 11 , wherein the first charging step is performed by applying a voltage of 1.0 V to 4.5 V at a constant current of 0.01 C to 5 C in a state in which the battery case is not sealed after the injection of the first electrolyte.

38 . The method of claim 11 , wherein the SEI film-forming agent comprises a cyclic carbonate-based compound containing an unsaturated bond, and
the first electrolyte comprises at least one lithium salt selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiBF 4 , LiBF

Assignees

• Lg Chemical Ltd

Inventors

• Yu Sung Hoon
• Kang Yoo Sun
• Lee Kyung Mi

Classifications

• H01M10/058 Primary

  Construction or manufacture · CPC title

• H01M2300/0042

  Four or more solvents · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title