JP-7857382-B2 - Method for producing silicon-containing composite particles

Inventors

• ヤン、ティルマン
• ジョシュア、ウィッタム
• クリストフ、ドレガー
• アレナ、カリヤキナ
• セバスティアン、クナイスル
• トーマス、レンナー
• リチャード、グレゴリー、テイラー
• ホセ、メドラノ－カタラン
• マークス、アンダーソン
• チャールズ、エイ．メイスン

Assignees

• ワッカー ケミー アクチエンゲゼルシャフト
• ネクシオン リミテッド

Dates

Publication Date

20260512

Application Date

20241211

Priority Date

20201130

Claims (16)

1. A method for producing silicon-containing composite particles, wherein the method comprises the following steps: (a) A step of providing a plurality of porous conductive particles including micropores and/or mesopores, (i) The D 50 particle diameter of the porous conductive particles is in the range of 0.5 to 200 μm. (ii) The total pore volume of micropores and mesopores measured by gas adsorption is in the range of 0.4 to 2.2 cm³ /g. (iii) A process in which the PD 50 pore size measured by gas adsorption is 30 nm or less, (b) A step in a batch-type pressure reactor to combine the charge of porous conductive particles with a charge of silicon-containing precursor, wherein the charge of porous conductive particles has a volume of at least 20 cm³ per liter of reactor volume ( cm³ /L RV ), and the charge of silicon-containing precursor contains at least 2 g of silicon per liter of reactor volume ( cm³ /L RV ), (c) A step of heating the reactor to a temperature effective in causing silicon to deposit in the pores of the porous conductive particles, thereby providing the silicon-containing composite particles, Includes, The batch-type pressure reactor is a moving-bed batch-type pressure reactor. A method wherein the porous particles are stirred during step (c).
2. The method according to claim 1, wherein the moving-bed batch pressure reactor is selected from a moving reactor, a reactor having a moving stirring element, a gas-pass reactor, or a combination thereof.
3. The method according to claim 2, wherein the moving bed batch pressure reactor is a fluidized bed reactor.
4. The method according to claim 1, wherein the batch-type pressure reactor has a moving stirring element.
5. The method according to claim 4, wherein the movement of the one or more stirring elements is rotational movement.
6. The method according to claim 5, wherein the batch-type pressure reactor is operated horizontally or vertically.
7. The method according to claim 6, wherein the batch-type pressure reactor is operated vertically, and the one or more stirring elements are selected from the group consisting of a helical stirrer, a spiral stirrer, and an anchor stirrer.
8. The method according to claim 6, wherein the batch-type pressure reactor is operated horizontally, and the one or more stirring elements are selected from the group consisting of blades, paddles, blade stirrers, and spiral stirrers.
9. The method according to claim 4, wherein the batch-type pressure reactor is an autoclave reactor equipped with an internal agitator.
10. The method according to claim 9, wherein the autoclave is equipped with a close- clearance helical stirrer.
11. The method according to any one of claims 1 to 10, wherein the pressure in step (c) is at least 200 kPa, or at least 300 kPa, or at least 500 kPa, or at least 700 kPa, or at least 1,000 kPa, or at least 1,500 kPa, or at least 2,000 kPa, or at least 2,500 kPa, or at least 3,000 kPa, or at least 4,000 kPa, or at least 5,000 kPa.
12. The method according to any one of claims 1 to 11, wherein the temperature in step (c) is within the range of 300 to 800°C, or 300 to 750°C, or 300 to 700°C, or 300 to 650°C, or 300 to 600°C, or 320 to 550°C, or 320 to 500°C, or 340 to 450°C, or 350 to 450°C, or 300 to 395°C, or 320 to 380°C.
13. The method according to any one of claims 1 to 12, wherein the batch pressure reactor includes, in addition to the silicon-containing precursor, an inert padding gas or hydrogen.
14. A step of bringing the surface of the deposited silicon into contact with a passivating agent, wherein the silicon is not exposed to oxygen before contact with the passivating agent. The method according to any one of claims 1 to 13, further comprising:
15. The method according to any one of claims 1 to 14, wherein the batch pressure reactor includes an integrated hydrogen-selective membrane.
16. The method according to claim 15, wherein the by-product hydrogen gas is discharged from the reactor as the reaction progresses.

Description

This invention relates to a method for producing silicon-containing composite particles by depositing silicon within the pores of porous particles. Silicon-containing composite particles are generally suitable for use as a negative electrode active material in metal-ion secondary batteries. Rechargeable metal-ion batteries are widely used in portable electronic devices such as mobile phones and laptops, and their application in electric and hybrid vehicles is progressing. Rechargeable metal-ion batteries generally include a negative electrode in the form of a metal current collector with a layer of electroactive material, defined as a material capable of inserting and releasing metal ions during charging and discharging of the battery. The terms “positive electrode” and “negative electrode” are used herein to mean that the battery is positioned across the load such that the negative electrode is the negative terminal. When a metal-ion battery is charged, metal ions are transported from the metal-ion-containing positive electrode layer through the electrolyte to the negative electrode and inserted into the negative electrode material. In this specification, the term “battery” is used to refer to both a device containing a single positive electrode and a single negative electrode, and a device containing multiple positive electrodes and/or multiple negative electrodes. We are interested in improving the gravimetric and/or volumetric capacity of rechargeable metal-ion batteries. To date, commercially available lithium-ion batteries have been limited to those using graphite as the negative electrode active material. When the graphite negative electrode is charged, lithium intercalates between the graphite layers, forming a material with the empirical formula Li x C 6 (where x is greater than 0 and less than or equal to 1). As a result, the maximum theoretical capacity of a graphite lithium-ion battery is 372 mAh/g, while the practical capacity is somewhat lower (approximately 340–360 mAh/g). Other materials such as silicon, tin, and germanium can intercalate lithium at considerably higher capacities than graphite, but they are not yet widely used commercially because it is difficult to maintain sufficient capacity over a large number of charge-discharge cycles. Silicon, in particular, is recognized as a promising alternative to graphite in the manufacture of rechargeable metal-ion batteries with high gravimetric and volumetric capacities due to its very large capacity relative to lithium (see, for example, Insertion Electrode Materials for Rechargeable Lithium Batteries, Winter, M. et al. in Adv. Mater. 1998, 10, No. 10). At room temperature, silicon has a theoretical maximum specific capacity of approximately 3,600 mAh/g ( Li₁₅Si₄ base ) in lithium-ion batteries. However, when silicon is lithiumized to its maximum capacity through lithium intercalation into bulk silicon, the capacity of the silicon material increases significantly, by up to 400%. Repeated charging and discharging places significant mechanical stress on the silicon material, resulting in fracture and delamination of the silicon anode material. The volume contraction of silicon particles due to delamination can cause a loss of electrical contact between the negative electrode material and the current collector. Furthermore, a drawback is that the solid electrolyte interface (SEI) layer formed on the silicon surface does not have sufficient mechanical resistance to accommodate the expansion and contraction of silicon. As a result, when the silicon surface is newly exposed, the electrolyte decomposes, the thickness of the SEI layer increases, and lithium is irreversibly consumed. These failure mechanisms lead to an unacceptable decrease in electrochemical capacity during continuous charge-discharge cycles. Many methods have been proposed to solve the problems associated with capacity changes observed during charging of silicon-containing negative electrodes. Fine silicon structures with cross-sections of 150 nm or less, such as silicon films and silicon nanoparticles, have been reported to be more resistant to capacity changes during charging and discharging compared to micron-sized silicon particles. However, none of these are suitable for commercial-scale applications in their original state; nanoscale particles are difficult to prepare and handle, and silicon films do not provide sufficient bulk capacity. WO2007/083155 discloses that improved capacity retention may be achieved by using silicon particles with a high aspect ratio, i.e., the ratio of the maximum particle size to the minimum particle size. The small cross-section of such particles reduces structural stress on the material caused by capacity changes during charge and discharge. However, such particles can be difficult and costly to manufacture and can be fragile. Furthermore, the high surface area can lead to excessive SEI formation, potentially resulting in excessive capacity loss