Search

US-12617687-B2 - Process for preparing electroactive materials for metal-ion batteries

US12617687B2US 12617687 B2US12617687 B2US 12617687B2US-12617687-B2

Abstract

The invention relates to a process for preparing composite particles, the process comprising contacting the plurality of particles in the reaction zone with a gas comprising at least 25 vol % of a silicon-containing precursor at a temperature effective to cause deposition of silicon in the pores of the porous particles. A controlled temperature differential between the maximum temperature of the internal surfaces of the reaction zone and the simultaneous minimum temperature within the plurality of porous particles is maintained during the contacting step.

Inventors

  • Jose MEDRANO CATALAN
  • Markus Andersson

Assignees

  • NEXEON LIMITED

Dates

Publication Date
20260505
Application Date
20250808
Priority Date
20220408

Claims (20)

  1. 1 . A process for preparing composite particles, the process comprising the steps of: (a) providing a plurality of porous particles in a reaction zone, the reaction zone having internal surfaces; and (b) contacting the plurality of particles in the reaction zone with a gas comprising at least 25 vol % of a silicon-containing precursor at a temperature effective to cause deposition of silicon in the pores of the porous particles; wherein ΔT≤+90° C. is maintained during step (b), wherein ΔT represents the temperature differential between the maximum temperature of the internal surfaces of the reaction zone and the simultaneous minimum temperature within the plurality of porous particles, wherein a positive value of ΔT indicates that the maximum temperature of the internal surfaces of the reaction zone is higher than the minimum temperature within the plurality of particles; and wherein step (b) comprises continuously agitating the porous particles during said contacting.
  2. 2 . The process according to claim 1 , wherein the ΔT maintained during step (b) is in the range from +90° C. to −110° C., or from +85° C. to −110° C., or from +80° C. to −110° C., or from +75° C. to −110° C., or from +70° C. to −110° C., or from +65° C. to −110° C., or from +60° C. to −110° C., or from +55° C. to −110° C., or from +50° C. to −110° C., or from +45° C. to −110° C., or from +40° C. to −110° C., or from +35° C. to −110° C., or from +30° C. to −110° C., or from +25° C. to −110° C., or from +20° C. to −110° C., or from +15° C. to −110° C., or from +10° C. to −110° C., or from +5° C. to −110° C., or from 0° C. to −110° C., or from −5° C. to −110° C., or from −5° C. to −105° C., or from −5° C. to −100° C., or from −5° C. to −95° C., or from −5° C. to −90° C., or from −5° C. to −85° C., or from −5° C. to −80° C., or from −5° C. to −75° C., or from −5° C. to −70° C., or from −5° C. to −65° C., or from −5° C. to −60° C., or from −5° C. to −55° C., or from −5° C. to −50° C., or from −5° C. to −45° C., or from −5° C. to −40° C., or from −5° C. to −35° C., or from −5° C. to −30° C., or from −5° C. to −25° C., or from −5° C. to −20° C., or from −5° C. to −15° C., or from −5° C. to −10° C.
  3. 3 . A process for preparing composite particles, the process comprising the steps of: (a) providing a plurality of porous particles in a reaction zone, the reaction zone having internal surfaces; and (b) contacting the plurality of particles in the reaction zone with a gas comprising at least 25 vol % of a silicon-containing precursor at a temperature effective to cause deposition of silicon in the pores of the porous particles; wherein ΔT≤+40° C. is maintained during step (b), wherein ΔT represents the temperature differential between the maximum temperature of the internal surfaces of the reaction zone and the simultaneous minimum temperature within the plurality of porous particles, wherein a positive value of ΔT indicates that the maximum temperature of the internal surfaces of the reaction zone is higher than the minimum temperature within the plurality of particles; and wherein the minimum temperature within the plurality of porous particles during said contacting in step (b) is in the range from 360 to 395° C.
  4. 4 . The process according to claim 1 , wherein step (a) comprises preheating the plurality of porous particles before providing the plurality of porous particles in the reaction zone, preferably wherein the plurality of porous particles are preheated to a temperature of from 300 to 480° C., or from 320 to 450° C., or from 330 to 400° C., or from 340 to 390° C., or from 345 to 390° C., or from 350 to 400° C., or from 350 to 390° C., or from 350 to 385° C., or from 350 to 380° C., or from 355 to 390° C., or from 355 to 385° C., or from 355 to 380° C., or from 360 to 390° C., or from 360 to 385° C., or from 360 to 380° C.
  5. 5 . The process according to claim 1 , wherein step (a) comprises providing a batch of the plurality of porous particles in the reaction zone.
  6. 6 . The process according to claim 1 , wherein the maximum temperature of the internal surfaces of the reaction zone during said contacting in steps (b) is from 150 to 480° C., or from 150 to 460° C., or from 150 to 440° C., or from 150 to 420° C., or from 150 to 400° C., or from 150 to 390° C., or from 200 to 390° C., or from 250 to 390° C., or from 300 to 390° C., or from 340 to 375° C., or from 340 to 370° C., or from 345 to 370° C., or from 345 to 365° C., or from 350 to 400° C., or from 350 to 390° C., or from 350 to 380° C., or from 350 to 370° C., or from 350 to 365° C.
  7. 7 . The process according to claim 1 , wherein step (b) comprises continuously introducing the gas comprising the silicon-containing precursor into the reaction zone.
  8. 8 . The process according to claim 1 , wherein step (b) comprises mechanically continuously agitating the porous particles during said contacting, preferably wherein the reaction zone comprises an agitator for continuously agitating the porous particles during said contacting, preferably wherein said agitating is carried out by a high shear mixer.
  9. 9 . The process according to claim 1 , wherein the plurality of porous particles in the reaction zone in step (a) has a volume of at least 100 cm 3 per litre of reaction zone (cm 3 /L RV ), or at least 150 cm 3 /L RV , or at least 200 cm 3 /L RV , or at least 250 cm 3 /L RV , or at least 300 cm 3 /L RV , or at least 400 cm 3 /L RV , or at least 500 cm 3 /L RV , or at least 600 cm 3 /L RV , or at least 700 cm 3 /L RV , or at least 800 cm 3 /L RV , or at least 900 cm 3 /L RV .
  10. 10 . The process according to claim 1 , wherein the silicon-containing precursor is selected from the group consisting of silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), methylsilane, dimethylsilane and chlorosilanes, and mixtures thereof.
  11. 11 . The process according to claim 1 , wherein the pressure in step (b) is from 10 to 15000 kPa, or from 50 to 10000 kPa, or from 120 to 5000 kPa, or from 150 to 2000 kPa, or from 200 to 1800 kPa, or from 200 to 1600 kPa, or from 250 to 1500 kPa, or from 300 to 1200 kPa, or from 400 to 1000 kPa, or from 500 to 900 kPa, or from 600 to 800 kPa.
  12. 12 . The process according to claim 1 , wherein the gas comprising the silicon-containing precursor comprises at least 30 vol % of silicon-containing precursor based on the total volume of the gas, or at least 40 vol %, or at least 50 vol %, or at least 60 vol %, or at least 70 vol %, or at least 80 vol %, or at least 90 vol %, or at least 95 vol %, or at least 97 vol %, or at least 99 vol % of silicon-containing precursor based on the total volume of the gas.
  13. 13 . The process according to claim 1 , wherein: (i) the plurality of porous particles have a BET surface area in the range from 1,000 m 2 /g to 3,000 m 2 /g, (ii) ΔT in step (b) is ≤+20° C. (iii) the plurality of porous particles is maintained within a temperature range from 370 to 395° C. during step (b); (iv) the ratio of the internal surface area of the reaction zone to mass of porous particles in the reaction zone in step (a) is no more than 0.4 m 2 /kg; and (v) step (b) comprises continuously agitating the porous particles.
  14. 14 . The process according to claim 1 , wherein the process further comprises the step of: forming a passivation layer on the surface of the silicon deposited in step (b) by contacting the particles from step (b) with a passivating agent.
  15. 15 . The process according to claim 1 , wherein the process further comprises the step of: contacting the particles from step (b) with a carbon-containing precursor at a temperature effective to cause deposition of a pyrolytic carbon material in the pores of the particles.
  16. 16 . The process according to claim 3 , wherein step (a) comprises preheating the plurality of porous particles before providing the plurality of porous particles in the reaction zone, preferably wherein the plurality of porous particles are preheated to a temperature of from 300 to 480° C., or from 320 to 450° C., or from 330 to 400° C., or from 340 to 390° C., or from 345 to 390° C., or from 350 to 400° C., or from 350 to 390° C., or from 350 to 385° C., or from 350 to 380° C., or from 355 to 390° C., or from 355 to 385° C., or from 355 to 380° C., or from 360 to 390° C., or from 360 to 385° C., or from 360 to 380° C.
  17. 17 . The process according to claim 3 , wherein step (a) comprises providing a batch of the plurality of porous particles in the reaction zone.
  18. 18 . The process according to claim 3 , wherein step (b) comprises continuously introducing the gas comprising the silicon-containing precursor into the reaction zone.
  19. 19 . The process according to claim 3 , wherein the plurality of porous particles in the reaction zone in step (a) has a volume of at least 100 cm 3 per litre of reaction zone (cm 3 /L RV ), or at least 150 cm 3 /L RV , or at least 200 cm 3 /L RV , or at least 250 cm 3 /L RV , or at least 300 cm 3 /L RV , or at least 400 cm 3 /L RV , or at least 500 cm 3 /L RV , or at least 600 cm 3 /L RV , or at least 700 cm 3 /L RV , or at least 800 cm 3 /L RV , or at least 900 cm 3 /L RV .
  20. 20 . The process according to claim 3 , wherein the silicon-containing precursor is selected from the group consisting of silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), methylsilane, dimethylsilane and chlorosilanes, and mixtures thereof.

Description

PRIORITY APPLICATIONS This application is a continuation of and claims the benefit of priority of U.S. application Ser. No. 18/855,051, filed Oct. 8, 2024, which is a U.S. National Stage Filing under 35 U.S.C. § 371 from International Application No. PCT/GB2023/050965, filed on Apr. 11, 2023, and published as WO2023/194753 on Oct. 12, 2023, which claims the benefit of priority to British Application No. 2205193.2, filed on Apr. 8, 2022; the benefit of priority of each of which is hereby claimed herein, and which applications and publication are hereby incorporated herein by reference in their entireties. FIELD OF THE INVENTION The invention relates to processes and systems for preparing electroactive materials that are suitable for use in metal-ion batteries, using chemical vapour infiltration (CVI) to deposit silicon in the pores of porous particulate material. BACKGROUND The present inventors have previously reported the development of a class of electroactive materials having a composite structure in which nanoscale electroactive materials, such as silicon, are deposited into the pores of a highly porous particulate material, e.g. a porous carbon material. For example, WO 2020/128495 discloses such particulate materials comprising a plurality of composite particles. The materials described in WO 2020/128495 have been synthesized using CVI. The porous particles are contacted with silane gas at temperatures of from 400 to 500° C. Low concentrations of silane are used, such as 1.25 vol %. Such prior CVI methods are adequate for laboratory scale production, but are unsuitable for a large-scale manufacture. For example, use of such low concentrations of a silicon-containing precursor means that the production time of the composite particles is unacceptable for a large-scale. Furthermore, it has been discovered that the prior processes of depositing silicon in the pores of porous particles using a CVI method result in uncontrolled soiling of the reaction zone. In particular, relatively large flakes of a composite rich in silicon can form on the internal surfaces of the reaction zone. Such flaking behaviour is detrimental to production as the soiled material can fragment and mix into the particulate material, even after post-production processes such as sieving. This degrades the quality of the particulate material and can cause undesired effects within electrode formulations, such as uneven expansion and loss of contact. It has also been identified that the formation of silicon flakes on the internal surfaces of the reaction zone is correlated with the formation of composite particles having a high content of coarse silicon, as defined herein. Coarse silicon is understood by the inventors to be one symptom of non-homogenous silicon deposition. Accordingly, soiling of the reaction zone is believed to correlate with poorly controlled silicon deposition into the porous particles. In large-scale production, the soiling could completely immobilise production. Halting production to remove the soiled material causes unacceptable delays and troublesome procedures for cleaning. Some CVI methods such as fixed bed, conveyor bed and vibratory fluidised bed methods rely on a high ratio of reactor surface area per mass of porous particles and a low bed thickness to achieve sufficient heat transfer to the porous particles. In addition to the risk of soiling, the scale-up of such methods is restricted. To increase the throughput of technologies reliant on a relatively high ratio of reactor surface area to mass of porous particles would require a proportional increase of reactor surface area. There is therefore a need to solve the abovementioned problems. SUMMARY OF INVENTION In a first aspect, the invention provides a process for preparing composite particles, the process comprising the steps of: (a) providing a plurality of porous particles in a reaction zone, the reaction zone having internal surfaces; and(b) contacting the plurality of particles in the reaction zone with a gas comprising at least 25 vol % of a silicon-containing precursor at a temperature effective to cause deposition of silicon in the pores of the porous particles; wherein ΔT≤+90° C. is maintained during step (b), wherein ΔT represents the temperature differential between the maximum temperature of the internal surfaces of the reaction zone and the simultaneous minimum temperature within the plurality of porous particles, wherein a positive value of ΔT indicates that the maximum temperature of the internal surfaces of the reaction zone is higher than the minimum temperature within the plurality of particles. In another aspect, the invention provides a system for preparing composite particles, the system comprising: (a) a reaction zone configured to hold a plurality of porous particles, the reaction zone having: (i) at least one heat source configured to heat the plurality of porous particles;(ii) at least one gas inlet for receiving a gas compris