Electroactive materials for metal-ion batteries
This invention relates to particulate electroactive materials comprising a plurality of composite particles, wherein the composite particles comprise: (a) a porous carbon framework including micropores and optional mesopores having a total volume of at least 0.7 cm 3 /g and up to 2 cm 3 /g, wherein at least half of the total micropore and mesopore volume is in the form of pores having a diameter of no more than 1.5 nm; and (b) silicon located within the micropores and optional mesopores of the porous carbon framework in a defined amount relative to the total volume of the micropores and optional mesopores.
1. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:
(a) a porous carbon framework comprising micropores and mesopores,
wherein the micropores and mesopores have a total pore volume as measured by gas adsorption of P 1 cm 3 /g, wherein P 1 has a value of at least 0.75 and up to 1.5, and
wherein the PD 50 pore diameter as measured by gas adsorption is no more than 1.5 nm; and
(b) a plurality of elemental nanoscale silicon domains located at least within the micropores of the porous carbon framework;
wherein the weight ratio of silicon to the porous carbon framework in the composite particles is in the range from [0.65×P 1 to 1.3×P 1 ]:1, and
wherein at least 90 wt % of the silicon mass in the composite particles is located within the internal pore volume of the porous carbon framework.
2. A particulate material according to claim 1 , wherein P 1 has a value of at least 0.8.
3. A particulate material according to claim 1 , wherein P 1 has a value of up to 1.3.
4. A particulate material according to claim 1 , wherein the PD 50 pore diameter of the porous carbon framework is no more than 1.4 nm.
5. A particulate material according to claim 1 , wherein the PD 60 pore diameter of the porous carbon framework is no more than 2 nm.
6. A particulate material according to claim 5 , wherein the PD 70 pore diameter of the porous carbon framework is no more than 2.5 nm.
7. A particulate material according to claim 6 , wherein the PD 80 pore diameter of the porous carbon framework is no more than 3 nm.
8. A particulate material according to claim 1 , wherein the PD 90 pore diameter of the porous carbon framework is no more than 10 nm.
9. A particulate material according to claim 8 , wherein the PD 95 pore diameter of the porous carbon framework is no more than 15 nm.
10. A particulate material according to claim 1 , wherein the porous carbon framework has a monomodal pore size distribution.
11. A particulate material according to claim 1 , wherein the porous carbon framework has a bimodal or multimodal pore size distribution.
12. A particulate material according to claim 11 , wherein the porous carbon framework has a bimodal or multimodal pore size distribution including at least one peak at less than 2 nm and at least one peak in the range from 5 to 50 nm.
13. A particulate material according to claim 1 , wherein the porous carbon framework comprises macropores having a diameter in the range from greater than 50 nm to 100 nm having a total volume P 2 cm 3 /g as measured by mercury porosimetry, wherein P 2 is no more than 0.2×P 1 .
14. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework is in the range from [1×P 1 to 1.3×P 1 ]:1.
15. A particulate material according to claim 1 , wherein at least a portion of the micropores comprise void space that is fully enclosed by the silicon.
16. A particulate material according to claim 1 , wherein the composite particles have a D 50 particle diameter in the range of 0.5 to 50 μm.
17. A particulate material according to claim 16 , wherein the composite particles have a D 50 particle diameter of at least 1 μm.
18. A particulate material according to claim 16 , wherein the composite particles have a D 50 particle diameter of no more than 40 μm.
19. A particulate material according to claim 1 , wherein the composite particles have a D 10 particle diameter of at least 0.2 μm.
20. A particulate material according to claim 1 , wherein the composite particles have a D 90 particle diameter of no more than 80 μm.
21. A particulate material according to claim 1 , wherein the composite particles have a BET surface area of at least 0.1 m 2 /g and no more than 60 m 2 /g.
22. A particulate material according to claim 1 , wherein the volume of micropores and mesopores of the composite particles, as measured by nitrogen gas adsorption, is no more than 0.15×P 1 .
23. A particulate material according to claim 1 , having specific capacity on lithiation of 1200 to 2340 mAh/g.
24. A particulate material according to claim 1 , wherein
the PD 50 pore diameter of the porous carbon framework is no more than 1.4 nm; and
the PD 80 pore diameter of the porous carbon framework is no more than 3 nm.
25. A particulate material according to claim 24 , wherein the composite particles have a BET surface area of at least 0.1 m 2 /g and no more than 60 m 2 /g and a D 50 particle diameter in the range of 0.5 to 50 μm.
26. A particulate material according to claim 1 , wherein the sum of the amount of silicon and carbon of the composite particles is at least 85%, and the sum of the amount of silicon, carbon and oxygen is at least 95 wt %.
27. A composition comprising a particulate material as defined in claim 1 , and at least one other component selected from: (i) a binder; (ii) a conductive additive; and (iii) an additional particulate electroactive material.
28. An electrode comprising a particulate material as defined in claim 1 in electrical contact with a current collector.
29. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode as described in 28 ;
(ii) a cathode comprising a cathode active material capable of releasing and reabsorbing metal ions; and
(iii) an electrolyte between the anode and the cathode.
30. A particulate material according to claim 1 , wherein
the PD 70 pore diameter of the porous carbon framework is no more than 3 nm; and
the PD 90 pore diameter of the porous carbon framework is no more than 10 nm.
31. A particulate material according to claim 1 , wherein the volume of silicon in the composite particles is equivalent to 20% to 55% of the total micropore/mesopore volume P 1 cm 3 /g of the porous carbon framework.
32. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework is in the range from [1×P 1 to 1.3×P 1 ]:1.
33. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework is in the range from [1×P 1 to 1.3×P 1 ]:1, and wherein P 1 has a value of up to 1.3.
34. A particulate material according to claim 1 , wherein the composite particles are spheroidal particles having an average sphericity S av of at least 0.70.
35. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:
(a) a porous carbon framework comprising micropores and optional mesopores,
wherein the micropores and optional mesopores have a total pore volume as measured by gas adsorption of P 1 cm 3 /g, wherein P 1 has a value of at least 0.75 and up to 1.5, and
wherein the PD 50 pore diameter as measured by gas adsorption is no more than 1.5 nm; and
(b) a plurality of elemental nanoscale silicon domains located at least within the micropores of the porous carbon framework;
wherein the weight ratio of silicon to the porous carbon framework in the composite particles is in the range from [0.65×P 1 to 1.3×P 1 ]:1, and wherein at least 90 wt % of the silicon mass in the composite particles is located within the internal pore volume of the porous carbon framework.
36. A particulate material according to claim 35 , wherein P 1 has a value of up to 1.3.