Electroactive materials for metal-ion batteries
The invention relates to a particulate material comprising a plurality of composite particles, wherein the composite particles comprise: (a) a porous carbon framework comprising micropores and mesopores having a total pore volume of at least 0.6 cm 3 /g and no more than 2 cm 3 /g, where the volume fraction of micropores is in the range from 0.5 to 0.9 and the volume fraction of pores having a pore diameter no more than 10 nm is at least 0.75, and the porous carbon framework has a D 50 particle size of less than 20 μm; (b) silicon located within the micropores and/or mesopores of the porous carbon framework in a defined amount relative to the volume of the micropores and/or 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
(i) 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 0.65 and no more than 2,
(ii) the volume fraction of micropores (φ a ) is in the range from 0.5 to 0.9, based on the total volume of micropores and mesopores,
(iii) the volume fraction of pores having a pore diameter no more than 5 nm (φ 5 ) is at least 0.70, based on the total volume of micropores and mesopores, and
(iv) the porous carbon framework has a D 50 particle size of less than 20 μm; and
(b) a plurality of nanoscale elemental silicon domains located within the micropores and/or mesopores 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 [1×P 1 to 1.9×P 1 ]:1.
2. A particulate material according to claim 1 , wherein P 1 has a value of at least 0.7.
3. A particulate material according to claim 1 , wherein P 1 has a value of no more than 1.8.
4. A particulate material according to claim 1 , wherein the volume fraction of micropores (φ a ) is in the range from 0.5 to 0.85.
5. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework in the composite particles is at least the value given by [φ b +0.75]×P 1 to the value given by [φ b +1.6]×P 1 , wherein φ b represents the volume fraction of mesopores, based on the total volume of micropores and mesopores.
6. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework in the composite particles is at least 1.1×P 1 and no more than the value given by [φ b +1.6]×P 1 .
7. A particulate material according to claim 1 , wherein the weight ratio of silicon to the porous carbon framework in the composite particles is at least 1.3×P 1 and no more than the value given by [φ b +1.6]×P 1 .
8. A particulate material according to claim 1 , wherein the volume fraction of pores having a pore diameter of no more than 10 nm (φ 5 ) is at least 0.8, based on the total volume of micropores and mesopores.
9. A particulate material according to claim 1 , wherein the porous carbon framework has a bimodal or multimodal pore size distribution.
10. A particulate material according to claim 9 , wherein the pore size distribution of the porous carbon framework has a first mode in the micropore range and a second mode in the mesopore size range.
11. A particulate material according to claim 10 , wherein the first mode and the second mode differ from one another by a factor in the range of 5-20.
12. 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 .
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 0.1×P 1 .
14. A particulate material according to claim 1 , wherein the composite particles have a D 10 particle diameter of at least 0.2 μm.
15. A particulate material according to claim 1 , wherein the composite particles have a D 90 particle diameter of no more than 40 μm.
16. A particulate material according to claim 1 , wherein at least 95 wt % of the silicon mass in the composite particles is located within the internal pore volume of the porous carbon framework.
17. A particulate material according to claim 1 , wherein
P 1 is in the range of 0.7-1.4;
φ a is in the range of 0.5-0.8;
φ 5 is at least 0.8; and
the D 50 particle size is in the range of 2-8 μm.
18. A particulate material according to claim 1 , wherein
P 1 is in the range of 0.7-1.4;
φ a is in the range of 0.5-0.8;
φ 5 is at least 0.8; and
the D 50 particle size is in the range of 2-8 μm.
19. A particulate material according to claim 1 , having specific capacity on lithiation of 1200 to 2340 mAh/g.
20. A particulate material according to claim 1 , wherein the composite particles have a sphericity of at least 0.7.
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. A composition according to claim 21 , comprising from 1 to 20 wt % of the particulate material, based on the total dry weight of the composition.
23. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode comprising a particulate material as defined in claim 1 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.
24. A particulate material according to claim 1 , wherein silicon is located within micropores and mesopores of the porous carbon framework.
25. A particulate material according to claim 1 , wherein the volume of micropores and mesopores in the composite particles, as measured by nitrogen gas adsorption, is no more than 0.10×P 1 .
26. A particulate material according to claim 1 , wherein the porous carbon framework comprises hard carbon.
27. A particulate material according to claim 1 , wherein the composite particles have an oxygen content that is less than 10 wt %.
28. A particulate material according to claim 1 , wherein the composite particles have a particle size distribution span of 3 or less.
29. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:
(a) a porous carbon framework comprising micropores and mesopores, wherein
(i) 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 in the range of 0.7-1.4,
(ii) the volume fraction of micropores (φ a ) is in the range from 0.5 to 0.8, based on the total volume of micropores and mesopores;
(iii) the volume fraction of pores having a pore diameter no more than 5 nm (φ 5 ) is at least 0.8, based on the total volume of micropores and mesopores, and
(iv) the porous carbon framework has a D 50 particle size in the range of 1-18 μm; and
(b) a plurality of nanoscale elemental silicon domains located within the micropores and/or mesopores 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 [1.2×P 1 to 1.8×P 1 ]:1.
30. A particulate material according to claim 29 , 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.
31. A particulate material according to claim 29 , wherein the sum of the amount of silicon and carbon of the composite particles is at least 85 wt %.
32. A particulate material according to claim 29 , wherein the composite particles have a sphericity of at least 0.7.
33. A particulate material according to claim 29 , wherein the composite particles have a sphericity of at least 0.7.
34. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:
(a) a porous carbon framework comprising micropores and mesopores, wherein
(i) 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 in the range of 0.6-1.8,
(ii) the volume fraction of micropores (φ a ) is in the range from 0.5 to 0.8, based on the total volume of micropores and mesopores,
(iii) the volume fraction of pores having a pore diameter no more than 10 nm (φ 10 ) is at least 0.9, based on the total volume of micropores and mesopores,
(iv) the volume fraction of pores having a pore diameter no more than 5 nm (φ 5 ) is at least 0.8, based on the total volume of micropores and mesopores, and
(iv) the porous carbon framework has a D 50 particle size in the range of 1-12 μm; and
(b) a plurality of nanoscale elemental silicon domains located within the micropores and/or mesopores 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 [1.2×P 1 to 1.8×P 1 ]:1, and is at least the value given by [φ b +0.8]×P 1 .
35. A particulate material according to claim 34 , 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.