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EP-4738503-A1 - ELECTROCHEMICAL DEVICE AND ELECTRONIC DEVICE

EP4738503A1EP 4738503 A1EP4738503 A1EP 4738503A1EP-4738503-A1

Abstract

The present application relates to an electrochemical device and an electronic device. The electrochemical device of the present application includes a positive electrode, a negative electrode, and an electrolyte. The electrolyte includes an additive, where the additive includes a first additive M, and the first additive M is at least one selected from the group consisting of a fluorinated carbonate compound and a compound containing a sulfur-oxygen double bond. The negative electrode includes a negative electrode active material layer, where the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a hard carbon material. The electrochemical device of the present application has improved high-temperature cycling performance, low-temperature performance, and rate performance while maintaining the specific capacity of the negative electrode active material.

Inventors

  • ZHENG, Zigui
  • Yi, Zheng
  • SHAO, WENLONG
  • XIE, YUANSEN

Assignees

  • Ningde Amperex Technology Limited

Dates

Publication Date
20260506
Application Date
20230630

Claims (12)

  1. An electrochemical device, comprising a positive electrode, a negative electrode, and an electrolyte; wherein the electrolyte comprises an additive, wherein the additive comprises a first additive M, the first additive M is at least one selected from the group consisting of a fluorinated carbonate compound and a compound containing a sulfur-oxygen double bond; and based on a mass of the electrolyte, a mass percentage of the first additive M is m%; the negative electrode comprises a negative electrode active material layer, wherein the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises a hard carbon material; as measured by Raman spectroscopy, a peak intensity of the hard carbon material at 1300 cm -1 to 1400 cm -1 is ID, a peak intensity of the hard carbon material at 1550 cm -1 to 1650 cm -1 is IG, a ratio of ID/IG is d, and d ranges from 1.0 to 1.6; and m/d ranges from 0.01 to 4.5.
  2. The electrochemical device according to claim 1, wherein the electrochemical device satisfies at least one of the following conditions: (1) m/d ranges from 1.6 to 3.6; or (2) d ranges from 1.2 to 1.4.
  3. The electrochemical device according to claim 1, wherein, as measured by X-ray diffraction, a crystal plane spacing d002 of the hard carbon material ranges from 0.37 nm to 0.41 nm.
  4. The electrochemical device according to claim 1, wherein the electrochemical device satisfies at least one of the following conditions: (1) based on the mass of the electrolyte, a mass percentage of the fluorinated carbonate compound ranges from 0.05% to 5%; or (2) based on the mass of the electrolyte, a mass percentage of the compound containing a sulfur-oxygen double bond ranges from 0.05% to 4%.
  5. The electrochemical device according to claim 3, wherein the crystal plane spacing d002 ranges from 0.38 nm to 0.40 nm.
  6. The electrochemical device according to claim 1, wherein the compound containing a sulfur-oxygen double bond comprises at least one of 1,3-propane sultone, propenyl-1,3-sultone, 1,2-propane sultone, 1,4-butane sultone, or vinyl sulfate, and/or the fluorinated carbonate compound comprises at least one of fluoroethylene carbonate or difluoroethylene carbonate.
  7. The electrochemical device according to claim 1, wherein the hard carbon material has pores, a pore diameter of the pores ranges from 0.6 nm to 2.0 nm; and, as measured by nitrogen adsorption, a pore volume of the pores is less than 0.05 cc/g.
  8. The electrochemical device according to claim 1, wherein the hard carbon material satisfies at least one of the following conditions: (1) a specific surface area of the hard carbon material ranges from 0.5 m 2 /g to 10 m 2 /g; (2) a compacted density of the hard carbon material under a pressure of 5 tons ranges from 0.8 g/cc to 1.6 g/cc; (3) as measured by X-ray diffraction, the hard carbon material has a diffraction peak in a range of 18° to 30°, and a full width at half maximum of the diffraction peak ranges from 4° to 12°; or (4) D v 50 of the hard carbon material ranges from 2 µm to 10 µm, and D v 50 and D v 90 of the hard carbon material satisfy: 2 ≤ D v 90/D v 50 ≤ 5.
  9. The electrochemical device according to claim 1, wherein the negative electrode active material layer satisfies at least one of the following conditions: (1) a porosity of the negative electrode active material layer ranges from 30% to 60%; or (2) a compacted density of the negative electrode active material layer ranges from 0.8 g/cc to 1.5 g/cc.
  10. The electrochemical device according to claim 1, wherein: a capacity per unit area of the negative electrode active material layer is V1; the positive electrode comprises a positive electrode active material layer, and a capacity per unit area of the positive electrode active material layer is V2; and V1/V2 ranges from 1.1 to 1.5.
  11. The electrochemical device according to claim 1, wherein the electrochemical device is a sodium-ion battery.
  12. An electronic device, comprising the electrochemical device according to any one of claims 1 to 11.

Description

TECHNICAL FIELD The present application relates to the field of energy storage, and in particular, to an electrochemical device and an electronic device. BACKGROUND With the widespread application of electrochemical devices, various types of batteries have been developed. A sodium-ion battery is a new type of rechargeable energy storage device, and its basic working principle is similar to that of a lithium-ion battery. Compared to traditional lithium-ion batteries, sodium-ion batteries have certain advantages in terms of cost, rate performance, low-temperature performance, and cycle life. Additionally, sodium-ion batteries offer higher safety. Currently, sodium-ion batteries have attracted widespread attention and have broad application prospects in fields such as electric vehicles and energy storage systems. Graphite materials are widely used as negative electrode active materials in lithium-ion batteries. However, due to the thermodynamic instability of compounds formed by graphite material and sodium, and the larger ionic radius of sodium ions, both of which prevent reversible intercalation/deintercalation in graphite layers, traditional graphite cannot be used as a negative electrode active material for sodium-ion batteries. Among the many negative electrode active materials for sodium-ion batteries under development, hard carbon materials have gained significant attention due to their high specific capacity and excellent rate performance, good low-temperature performance, and favorable cycle performance. Moreover, the precursors for hard carbon materials are widely available, common biomass materials, coal-based materials, pitch-based materials, and resin materials all serve as precursors for hard carbon materials, and these precursors are cost-effective. The heat treatment process for hard carbon materials also consumes less energy than that for graphite materials, and the cost advantages of raw materials and processing further enhance the cost-effectiveness of sodium-ion batteries. Hard carbon materials have a larger interlayer spacing, which facilitates the intercalation/deintercalation of sodium ions, thereby increasing the sodium-ion diffusion rate. Additionally, the presence of numerous pore defects within hard carbon materials allows for high sodium storage capacity, making them the most ideal negative electrode material for sodium-ion batteries at present. From the perspective of the sodium storage mechanism, the majority of the sodium storage capacity of hard carbon is achieved through filling at low potentials. These low potentials are close to the sodium deposition potential, which easily leads to sodium deposition. This not only causes irreversible capacity decay but may also result in gas generation and safety issues in electrochemical devices. Therefore, there is indeed a need to provide an improved electrochemical device using hard carbon as the negative electrode active material. SUMMARY The purpose of the present application is to provide an electrochemical device and an electronic device, where the electrochemical device of the present application has improved high-temperature cycling performance, low-temperature performance, and rate performance while maintaining the specific capacity of the negative electrode active material. The specific technical solution is as follows: In one embodiment, the present application provides an electrochemical device including a positive electrode, a negative electrode, and an electrolyte; where the electrolyte includes an additive, where the additive includes a first additive M, the first additive M is at least one selected from the group consisting of a fluorinated carbonate compound and a compound containing a sulfur-oxygen double bond, and based on a mass of the electrolyte, a mass percentage of the first additive M is m%; the negative electrode includes a negative electrode active material layer, where the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a hard carbon material; as measured by Raman spectroscopy, a peak intensity of the hard carbon material at 1300 cm-1 to 1400 cm-1 is ID, a peak intensity of the hard carbon material at 1550 cm-1 to 1650 cm-1 is IG, a ratio of ID/IG is d, d ranges from 1.0 to 1.6, and m/d ranges from 0.01 to 4.5. In some embodiments, the electrochemical device satisfies at least one of the following conditions: (1) m/d ranges from 1.6 to 3.6; or (2) d ranges from 1.2 to 1.4. In some embodiments, as measured by X-ray diffraction, a crystal plane spacing d002 of the hard carbon material ranges from 0.37 nm to 0.41 nm. In some embodiments, the crystal plane spacing d002 ranges from 0.38 nm to 0.40 nm. In some embodiments, the electrochemical device satisfies at least one of the following conditions: (1) based on the mass of the electrolyte, a mass percentage of the fluorinated carbonate compound ranges from 0.05% to 5%; or(2)