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KR-102962184-B1 - ANODE FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102962184B1KR 102962184 B1KR102962184 B1KR 102962184B1KR-102962184-B1

Abstract

The present invention relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the same. More specifically, the invention relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the same, wherein a fiber composite layer is included on an active material layer, thereby ensuring excellent elasticity and elastic recovery force even with volume expansion and contraction of the active material layer during charging and discharging, resulting in no change in electrode thickness, and excellent ion conductivity, thereby improving battery life and storage capacity.

Inventors

  • 이상하

Assignees

  • 현대자동차주식회사
  • 기아 주식회사

Dates

Publication Date
20260507
Application Date
20190610

Claims (17)

  1. It is composed of 30 to 70 weight% of a first fiber; and 30 to 70 weight% of a second fiber; and The first fiber and the second fiber are mixed such that at least a portion of the first fiber exists in the gap between the second fibers, and The first fiber mentioned above is a polyolefin fiber, and The second fiber mentioned above is selected from the group consisting of glass fiber, cellulose fiber, polyamide fiber, polyester fiber, polyacrylonitrile fiber, and combinations thereof. The above second fiber is a fiber composite for a lithium secondary battery with a hydrophilic surface formed by plasma treatment.
  2. The whole house; An active material layer including a negative electrode active material; and Includes a fiber composite layer; and The fiber composite layer above is, It is composed of 30 to 70 weight% of a first fiber; and 30 to 70 weight% of a second fiber; and The first fiber and the second fiber are mixed such that at least a portion of the first fiber exists in the gap between the second fibers, and The first fiber mentioned above is a polyolefin fiber, and The second fiber mentioned above is selected from the group consisting of glass fiber, cellulose fiber, polyamide fiber, polyester fiber, polyacrylonitrile fiber, and combinations thereof. The above second fiber is a negative electrode for a lithium secondary battery, having a hydrophilic surface after plasma treatment.
  3. In paragraph 2, The above negative electrode active material is a single-phase or alloy-phase oxide or sulfide selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi and combinations thereof, for a lithium secondary battery negative electrode.
  4. In paragraph 2, The first fiber has an average diameter of 0.01 μm to 20 μm and an average length of 50 μm to 10,000 μm, and The above second fiber has an average diameter of 0.01 μm to 20 μm and an average length of 50 μm to 10,000 μm, and is a negative electrode for a lithium secondary battery.
  5. The whole house; An active material layer including a negative electrode active material; and Includes a fiber composite layer; and The fiber composite layer above is, It is composed of 30 to 70 weight% of a first fiber; and 30 to 70 weight% of a filler; and The first fibers and the filler are mixed such that at least a portion of the filler exists in the gaps between the first fibers, and The first fiber mentioned above is a polyolefin fiber, and The above filler is selected from the group consisting of alumina, silica, zirconia, titania, and combinations thereof, for a negative electrode for a lithium secondary battery.
  6. In paragraph 5, The first fiber has an average diameter of 0.01 μm to 20 μm and an average length of 50 μm to 10,000 μm, and The above filler is a negative electrode for a lithium secondary battery having an average diameter of 0.01 μm to 20 μm and an average length of 50 μm to 10,000 μm.
  7. The whole house; An active material layer including a negative electrode active material; and Includes a fiber composite layer; and The fiber composite layer above is, It is composed of 30 to 70 weight% of a first fiber; and 30 to 70 weight% of a third fiber having a hydrophilic surface treatment of the first fiber; and The first fiber and the third fiber are mixed such that at least a portion of the first fiber exists in the gap between the third fibers, and The first fiber above is a polyolefin fiber, and The above third fiber is a negative electrode for a lithium secondary battery in which the surface of the above first fiber is treated with a hydrophilic polymer.
  8. In Paragraph 7, The above-mentioned first fiber has an average diameter of 0.01 μm to 20 μm and an average length of 50 μm to 10,000 μm, and is a negative electrode for a lithium secondary battery.
  9. In paragraph 2, The above fiber composite layer has a thickness of 1 to 500 μm and a porosity of 85 to 95%, and is a negative electrode for a lithium secondary battery.
  10. Anode; and A cathode according to any one of paragraphs 2 through 9; A lithium secondary battery including
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Description

Anode for lithium secondary battery and lithium secondary battery comprising the same The present invention relates to a negative electrode for a lithium secondary battery having no change in electrode thickness and excellent ion conductivity, thereby improving battery life, and a lithium secondary battery including the same. Lithium-ion batteries, which have recently gained popularity as power sources for small portable electronic devices, are batteries that exhibit high energy density by using an organic electrolyte and showing a discharge voltage more than twice as high as that of conventional batteries using an alkaline aqueous solution. Recently, these lithium-ion batteries are being used as power sources for automobiles. However, there is a problem in that the limited energy density limits the driving range of the vehicle. Various forms of carbon-based materials, including artificial graphite, natural graphite, and hard carbon capable of lithium insertion and extraction, have been applied as negative electrode active materials. Among these carbon-based materials, graphite, such as artificial or natural graphite, has a lower discharge voltage compared to lithium. Batteries using graphite as the negative electrode active material are the most widely used because they exhibit high discharge voltages, resulting in excellent energy density, and ensure a long lifespan for lithium-ion batteries through their outstanding reversibility. However, when manufacturing electrode plates using graphite as the active material, the electrode plate density is low, resulting in a problem of low capacity in terms of energy density per unit volume of the electrode plate. In addition, at high discharge voltages, side reactions between graphite and the organic electrolyte are likely to occur, posing a risk of battery malfunction and ignition or explosion due to overcharging. To solve these problems, metal-based cathode active materials have recently been developed. For example, amorphous tin oxide developed by Fujifilm exhibits a high capacity of 800 mAh/g by weight. In the case of silicon, another metal active material, it has a storage capacity (3000 mAh/g) that is more than eight times higher than that of graphite, so the development of silicon-based electrodes has also progressed significantly. However, these metal active materials have the problem of decomposing the electrolyte as they undergo repeated volume expansion and contraction during charging and discharging. Although the problem of electrolyte decomposition has been resolved by coating the surface of metal active materials with aluminum oxide, carbon materials, etc., changes in electrode thickness caused by the volume expansion and contraction of the active material still remain an issue. Recently, methods such as coating a high-strength binder layer on the surface of the negative electrode have been announced to address this. This high-strength binder layer is capable of transporting lithium ions and possesses suitable mechanical properties, allowing for efficient control of the expansion of the negative electrode plate. However, the lithium-ion conductivity of the polymer layer is limited, which causes a degradation in battery performance, particularly at low temperatures, making it impossible to use as an automotive battery. Additionally, while a bulky layer is used to address the instability of the inorganic active material interface, the recent use of carbon-coated active materials has resolved this issue, so the bulky layer no longer offers advantages. Figure 1 is a cross-sectional view of a conventional lithium secondary battery. FIG. 2 is a drawing showing one embodiment of a fiber composite layer of a negative electrode for a lithium secondary battery according to the present invention. FIG. 3 is a drawing showing another embodiment of a fiber composite layer of a negative electrode for a lithium secondary battery according to the present invention. FIG. 4 is a drawing showing another embodiment of a fiber composite layer of a negative electrode for a lithium secondary battery according to the present invention. FIG. 5 is a cross-sectional view of a lithium secondary battery according to the present invention. FIG. 6(a) is a cross-sectional view showing that the fiber composite layer shrinks when the negative electrode of a lithium secondary battery according to the present invention expands. Figure 6(b) is a cross-sectional view showing the expansion of the fiber composite layer when the negative electrode of a lithium secondary battery according to the present invention shrinks. Figure 7 is an SEM image of a cross-section of the negative electrode of a lithium secondary battery according to the present invention. The above objects, other objects, features, and advantages of the present invention will be easily understood through the following preferred embodiments associated with the accompanying drawings. However, the present invention is not limite