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CN-116250094-B - Secondary battery

CN116250094BCN 116250094 BCN116250094 BCN 116250094BCN-116250094-B

Abstract

The secondary battery comprises a positive electrode containing a lithium-nickel composite oxide, a negative electrode containing a lithium-titanium composite oxide, and an electrolyte containing a carboxylic acid ester containing at least one of ethyl acetate, propyl acetate, ethyl propionate, and propyl propionate. In surface analysis of a positive electrode using X-ray photoelectron spectroscopy, a first oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV inclusive and a second oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV inclusive are detected, and a ratio of an intensity of the first oxygen spectrum to an intensity of the second oxygen spectrum is 0.30 to 0.80 inclusive. In a surface analysis of a negative electrode using an X-ray photoelectron spectroscopy, a third oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV inclusive and a fourth oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV inclusive are detected, and a ratio of an intensity of the third oxygen spectrum to an intensity of the fourth oxygen spectrum is 0.82 to 1.35 inclusive.

Inventors

  • Zong Ganggaomin
  • KATAYAMA SHINICHI
  • Huang Muchunshi
  • KURATSUKA MASAKI
  • Fujikawa Takashinari
  • Dao Yangfu

Assignees

  • 株式会社村田制作所

Dates

Publication Date
20260512
Application Date
20210913
Priority Date
20200917

Claims (9)

  1. 1. A secondary battery is provided with: A positive electrode containing a lithium nickel composite oxide; a negative electrode comprising a lithium-titanium composite oxide, and An electrolyte containing a carboxylic acid ester, The carboxylic acid ester contains at least one of ethyl acetate, propyl acetate, ethyl propionate and propyl propionate, In the surface analysis of the positive electrode using X-ray photoelectron spectroscopy, a first oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV, and a second oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV were detected, The ratio of the intensity of the first oxygen spectrum to the intensity of the second oxygen spectrum is 0.30 or more and 0.80 or less, In the surface analysis of the negative electrode using the X-ray photoelectron spectroscopy, a third oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV, and a fourth oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV were detected, The ratio of the intensity of the third oxygen spectrum to the intensity of the fourth oxygen spectrum is 0.82 or more and 1.35 or less, The electrolyte contains a solvent and an electrolyte salt, The solvent contains the carboxylic acid ester, The content of the carboxylic acid ester in the solvent is 50% by weight or more and 90% by weight or less.
  2. 2. The secondary battery according to claim 1, wherein, The lithium nickel composite oxide contains a compound represented by the following formula (1), Li x Ni (1-y) M1 y O 2 ...(1), M1 is at least one element belonging to the second group to the fifteenth main group of the long periodic table other than Ni, x and y satisfy 0.8≤x≤1.2 and 0≤y <1.0.
  3. 3. The secondary battery according to claim 2, wherein, The ratio of the number of moles of Ni to the sum of the number of moles of Ni and the number of moles of M1 is 80% or more.
  4. 4. The secondary battery according to claim 1, wherein, The solvent also contains a cyclic carbonate.
  5. 5. The secondary battery according to any one of claims 1 to 4, wherein, The positive electrode includes: a positive electrode active material layer containing the lithium nickel composite oxide, and A positive electrode coating film provided on the surface of the positive electrode active material layer and containing oxygen as a constituent element, In the surface analysis of the positive electrode using the X-ray photoelectron spectroscopy, the positive electrode coating film is analyzed.
  6. 6. The secondary battery according to any one of claims 1 to 4, wherein, The lithium titanium composite oxide contains at least one compound represented by the following formula (2), formula (3) and formula (4), Li[Li x M2 (1-3x)/2 Ti (3+x)/2 ]O 4 ...(2), M2 is at least one of Mg, ca, cu, zn and Sr, x is more than or equal to 0 and less than or equal to 1/3, Li[Li y M3 1-3y Ti 1+2y ]O 4 ...(3), M3 is at least one of Al, sc, cr, mn, fe, ga and Y, Y satisfies 0≤y≤1/3, Li[Li 1/3 M4 z Ti (5/3)-z ]O 4 ...(4), M4 is at least one of V, zr and Nb, and z is more than or equal to 0 and less than or equal to 2/3.
  7. 7. The secondary battery according to any one of claims 1 to 4, wherein, The negative electrode includes: A negative electrode active material layer containing the lithium-titanium composite oxide, and A negative electrode coating film provided on the surface of the negative electrode active material layer and containing oxygen as a constituent element, In the surface analysis of the negative electrode using the X-ray photoelectron spectroscopy, the negative electrode coating film is analyzed.
  8. 8. The secondary battery according to any one of claims 1 to 4, wherein, The secondary battery further includes a flexible exterior cover that houses the positive electrode, the negative electrode, and the electrolyte.
  9. 9. The secondary battery according to any one of claims 1 to 4, wherein, The secondary battery is a lithium ion secondary battery.

Description

Secondary battery Technical Field The present technology relates to a secondary battery. Background Since various electronic devices such as mobile phones are popular, secondary batteries are being developed as small-sized, lightweight power sources capable of achieving high energy density at the same time. The secondary battery includes a positive electrode, a negative electrode, and an electrolyte, and various studies have been made on the structure of the secondary battery. Specifically, in order to obtain excellent cycle characteristics and the like, when a Ni-based compound is used as a positive electrode active material, the surface analysis result (the 1s spectrum intensity ratio of oxygen) of the Ni-based compound by X-ray photoelectron spectroscopy is optimized (for example, see patent literature 1.). In order to prevent occurrence of internal short-circuiting, when a composite oxide containing lithium and a transition metal M is used as a positive electrode active material and a thin film is formed on the surface of the positive electrode, the surface analysis result (intensity ratio of 2p spectrum of the transition metal M) of the positive electrode using X-ray photoelectron spectroscopy is optimized (for example, refer to patent document 2). In order to suppress expansion, in the case where titanium oxide is used as the anode active material and a coating film is formed on the surface of the anode, the analysis result (ratio of oxygen atoms) of the coating film using X-ray photoelectron spectroscopy is optimized (for example, see patent literature 3.). Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2005-251700 Patent document 2 Japanese patent laid-open publication No. 2003-338277 Patent document 3 Japanese patent application laid-open No. 2017-168465 Disclosure of Invention Although various studies have been made on the performance of secondary batteries, expansion characteristics, cycle characteristics, and load characteristics are still insufficient, and thus there is room for improvement. Therefore, a secondary battery capable of obtaining excellent expansion characteristics, excellent cycle characteristics, and excellent load characteristics is required. A secondary battery according to one embodiment of the present technology includes a positive electrode containing a lithium-nickel composite oxide, a negative electrode containing a lithium-titanium composite oxide, and an electrolyte solution containing a carboxylic acid ester containing at least one of ethyl acetate, propyl acetate, ethyl propionate, and propyl propionate. In surface analysis of a positive electrode using X-ray photoelectron spectroscopy, a first oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV inclusive and a second oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV inclusive are detected, and a ratio of an intensity of the first oxygen spectrum to an intensity of the second oxygen spectrum is 0.30 to 0.80 inclusive. In a surface analysis of a negative electrode using an X-ray photoelectron spectroscopy, a third oxygen spectrum having a peak in a range of a binding energy of 528eV to 531eV inclusive and a fourth oxygen spectrum having a peak in a range of a binding energy of more than 531eV to 535eV inclusive are detected, and a ratio of an intensity of the third oxygen spectrum to an intensity of the fourth oxygen spectrum is 0.82 to 1.35 inclusive. Here, "lithium nickel composite oxide" refers to the generic term of oxides containing lithium and nickel as constituent elements, and "lithium titanium composite oxide" refers to the generic term of oxides containing lithium and titanium as constituent elements. Details of each of the lithium nickel composite oxide and the lithium titanium composite oxide will be described later. According to the secondary battery of one embodiment of the present technology, the positive electrode contains a lithium nickel composite oxide, the negative electrode contains a lithium titanium composite oxide, and the electrolyte contains a carboxylic acid ester containing ethyl acetate or the like. The surface analysis result (ratio of the intensity of the first oxygen spectrum to the intensity of the second oxygen spectrum) of the positive electrode using the X-ray photoelectron spectroscopy satisfies the above condition, and the surface analysis result (ratio of the intensity of the third oxygen spectrum to the intensity of the fourth oxygen spectrum) of the negative electrode using the X-ray photoelectron spectroscopy satisfies the above condition. Therefore, excellent expansion characteristics, excellent cycle characteristics, and excellent load characteristics can be obtained. The effects of the present technology are not limited to those described herein, and may be any of a series of effects related to the present technology described below. Drawings Fig. 1 is a persp