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 combined total volume of at least 0.7 cm 3 /g, wherein at least half of the micropore/mesopore volume is in the form of pores having a diameter of no more than 1.5 nm; and (b) an electroactive material located within the micropores and/or mesopores of the porous carbon framework. The D 90 particle diameter of the composite particles is no more than 10 nm.
1. 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 2,
wherein the PD 50 pore diameter as measured by gas adsorption is no more than 1.5 nm; and
(b) silicon located within at least the micropores of the porous carbon framework, with at least 90 wt % of the silicon mass in the composite particles being located within the internal volume of the porous carbon framework;
wherein the composite particles have a D 90 particle diameter of no more than 10 μm.
2. A particulate material according to claim 1 , wherein P 1 has a value up to 1.6 cm 3 /g.
3. A particulate material according to claim 1 , wherein P 1 has a value of up to 1.8 cm 3 /g.
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 80 pore diameter of the porous carbon framework is no more than 3 nm.
6. A particulate material according to claim 1 , wherein the PD 90 pore diameter of the porous carbon framework is no more than 10 nm.
7. A particulate material according to claim 6 , wherein the PD 90 pore diameter of the porous carbon framework is no more than 8 nm.
8. A particulate material according to claim 1 , wherein the porous carbon framework has a bimodal or multimodal pore size distribution.
9. A particulate material according to claim 8 , 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 2.5 to 20 nm.
10. 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 .
11. 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.
12. A particulate material according to claim 1 , wherein the composite particles have a D 90 particle diameter of no more than 9.5 μm.
13. A particulate material according to claim 1 , wherein the composite particles have a D 50 particle diameter in the range of 0.5 to 7 μm.
14. A particulate material according to claim 13 , wherein the composite particles have a D 50 particle diameter of at least 1 μm and no more than 6.5 μm.
15. A particulate material according to claim 1 , wherein the composite particles have a D 10 particle diameter of at least 0.2 μm.
16. A particulate material according to claim 1 , wherein the composite particles have a D 99 particle diameter of no more than 25 μm.
17. A particulate material according to claim 1 , wherein the fill factor of the silicon in the porous carbon framework is no more than 55%.
18. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework is in the range from [0.5×P 1 to 1.3×P 1 ]:1.
19. 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 .
20. 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 150 m 2 /g.
21. A particulate material according to claim 1 , having specific capacity on lithiation of 1200 to 2340 mAh/g.
22. 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.
23. An electrode comprising a particulate material as defined in claim 1 in electrical contact with a current collector.
24. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode as described in claim 23 ;
(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.
25. A particulate material according to claim 1 , wherein the sum of the amount of silicon and carbon of the composite particles is at least 80 wt % of the composite particles.
26. A particulate material according to claim 1 , wherein the total oxygen content is less than 10 wt %.
27. A particulate material according to claim 1 , wherein the porous carbon framework comprises hard carbon.
28. 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 2,
wherein the PD 50 pore diameter as measured by gas adsorption is no more than 1.5 nm; and
(b) silicon located within at least the micropores of the porous carbon framework, with at least 90 wt % of the silicon mass in the composite particles being located within the internal volume of the porous carbon framework;
wherein the composite particles have a D 90 particle diameter of no more than 10 μm,
wherein the composite particles are spheroidal particles having an average sphericity S av of at least 0.70.
29. A particulate material according to claim 28 , wherein P 1 has a value in the range of 0.75 to 1.8 cm 3 /g.
30. A particulate material according to claim 28 , wherein the PD 50 pore diameter of the porous carbon framework is no more than 1.4 nm.
31. A particulate material according to claim 28 , 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 2.5 to 20 nm.
32. A particulate material according to claim 28 , 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 .
33. A particulate material according to claim 28 , wherein the fill factor of the silicon in the porous carbon framework is no more than 55%.
34. A particulate material according to claim 28 , wherein the weight ratio of silicon to the porous carbon framework is in the range from [0.5×P 1 to 1.3×P 1 ]:1.
35. A particulate material according to claim 28 , 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 .
36. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode comprising a particulate material as defined in claim 28 in electrical contact with a current collector;
(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.
37. A particulate material according to claim 28 , wherein the porous carbon framework is derived from pyrolysis of a polymer.
38. A particulate material according to claim 28 , wherein the average sphericity Say is at least 0.85.
39. 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 2,
wherein the PD 50 pore diameter as measured by gas adsorption is no more than 1.5 nm; and
(b) silicon located within at least the micropores of the porous carbon framework, with at least 90 wt % of the silicon mass in the composite particles being located within the internal volume of the porous carbon framework,
wherein the composite particles have a D 90 particle diameter of no more than 10 μm, and
wherein the particulate material has a volume-based particle size distribution having a positive skew.