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 volume of silicon in the composite particles is equal to 20-55% of the micropore and mesopore volume, 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 the volume of silicon in the composite particles is equal to 25-55% of the micropore and mesopore volume.
3. A particulate material according to claim 1 , wherein the volume of silicon in the composite particles is equal to 25-40% of the micropore and mesopore volume.
4. 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 .
5. 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 0.10×P 1 .
6. 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 and a span of 5 or less.
7. A particulate material according to claim 1 , wherein the composite particles have a D 50 particle diameter in the range of 5 to 30 μm and a span of 3 or less.
8. A particulate material according to claim 1 , wherein the sum of the amount of silicon and carbon of the composite particles is at least 90 wt % of the particulate material, and the amount of oxygen is less than 10 wt % of the particulate material.
9. A particulate material according to claim 1 , wherein the sum of the amount of silicon and carbon of the composite particles is at least 95 wt % of the particulate material, and the amount of oxygen is less than 5 wt % of the particulate material.
10. 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 ;
the composite particles have a D 50 particle diameter in the range of 0.5 to 50 μm and a span of 5 or less; and
the sum of the amount of silicon and carbon of the composite particles is at least 90 wt % of the particulate material, and the amount of oxygen is less than 10 wt % of the particulate material.
11. 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 0.10×P 1 ;
the composite particles have a D 50 particle diameter in the range of 5 to 30 μm and a span of 3 or less; and
the sum of the amount of silicon and carbon of the composite particles is at least 95 wt % of the particulate material, and the amount of oxygen is less than 5 wt % of the particulate material.
12. A particulate material according to claim 1 , 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.
13. 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.
14. A particulate material according to claim 1 , wherein P 1 has a value of at least 0.8.
15. A particulate material according to claim 1 , wherein P 1 has a value of up to 1.3.
16. A particulate material according to claim 1 , wherein the PD 60 pore diameter of the porous carbon framework is no more than 2 nm.
17. A particulate material according to claim 1 , wherein the PD 90 pore diameter of the porous carbon framework is no more than 10 nm.
18. 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 .
19. 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.
20. A particulate material according to claim 1 , having specific capacity on lithiation of 1200 to 2340 mAh/g.
21. 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.
22. An electrode comprising a particulate material as defined in claim 21 in electrical contact with a current collector.
23. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode as described in 22 ;
(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.