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 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 0.6 and no more than 2,
the volume fraction of pores having a pore diameter no more than 10 nm (φ 10 ) is at least 0.75, based on the total volume of micropores and mesopores, and
the porous carbon framework has a D 50 particle size of less than 20 μm; and
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 pores having a pore diameter in the range of 10-50 nm constitute up to 10% of the total volume of micropores and mesopores of the porous carbon framework.
3. A particulate material according to claim 1 , wherein the porous carbon framework has a volume fraction of pores having a diameter no more than 5 nm (φ 5 ) of at least 0.7.
4. 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 .
5. A particulate material according to claim 1 , wherein the composite particles have an average sphericity of at least 0.70.
6. A particulate material according to claim 1 , wherein the composite particles have an average sphericity of at least 0.90.
7. A particulate material according to claim 1 , wherein the porous carbon framework is a hard carbon framework.
8. A particulate material according to claim 1 , wherein the porous carbon framework is derived from pyrolysis of a polymeric material.
9. A particulate material according to claim 1 , wherein the porous carbon framework is an activated porous carbon framework.
10. A particulate material according to claim 9 , wherein the activated porous carbon framework is activated by being contacted with one or more of oxygen, steam, CO, CO 2 and KOH at a temperature in the range of 600-1000° C.
11. A particulate material according to claim 1 , wherein the composite particles have a conductive carbon coating formed thereon.
12. A particulate material according to claim 11 , wherein the conductive carbon coating is in the range of 2-30 nm in thickness.
13. A particulate material according to claim 1 , having a BET surface area in the range of 0.1-30 m 2 /g.
14. A particulate material according to claim 1 , having a BET surface area in the range of 1-25 m 2 /g.
15. A particulate material according to claim 1 , wherein P 1 has a value of at least 0.65 and no more than 1.8.
16. 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 .
17. A particulate material according to claim 1 , wherein the composite particles have a D 50 particle diameter of at least 0.5 μm.
18. A particulate material according to claim 1 , wherein
P 1 has a value of at least 0.65 and no more than 1.8;
the volume fraction of micropores (φ a ) is in the range from from 0.55 to 0.8; and
the weight ratio of silicon to the porous carbon framework in the composite particles is no more than 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.
19. An electrode comprising a current collector, and, in contact with the current collector, a composition comprising a particulate material according to claim 1 , and at least one other component selected from: (i) a binder; (ii) a conductive additive; and (iii) an additional particulate electroactive.
20. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode according to claim 19 ;
(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.
21. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:
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 0.6 and no more than 2,
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, and
the volume fraction of pores having a pore diameter no more than 10 nm (φ 10 ) is at least 0.75, based on the total volume of micropores and mesopores; and
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.
22. A particulate material according to claim 21 , wherein the composite particles have an average sphericity of at least 0.70.
23. A particulate material according to claim 21 , wherein the composite particles have an average sphericity of at least 0.90.
24. A particulate material according to claim 21 , wherein the porous carbon framework is a hard carbon framework.
25. A particulate material according to claim 21 , wherein the porous carbon framework is derived from pyrolysis of a polymeric material.
26. A particulate material according to claim 21 , wherein the porous carbon framework is an activated porous carbon framework, the activated porous carbon framework being activated by being contacted with one or more of oxygen, steam, CO, CO 2 and KOH at a temperature in the range of 600-1000° C.
27. A particulate material according to claim 21 , wherein the composite particles have a conductive carbon coating formed thereon, the conductive carbon coating being in the range of 2-30 nm in thickness.
28. A particulate material according to claim 21 , having a BET surface area in the range of 0.1-30 m 2 /g.
29. A particulate material according to claim 21 , wherein the weight ratio of silicon to the porous carbon framework in the composite particles is at least 1.1×P 1 .
30. A particulate material according to claim 21 , wherein the composite particles have a D 50 particle diameter in the range from 0.5 to 20 μm.
31. A particulate material according to claim 21 , wherein
P 1 has a value of at least 0.65 and no more than 1.8;
the volume fraction of micropores (φ a ) is in the range from from 0.55 to 0.8; and
the weight ratio of silicon to the porous carbon framework in the composite particles is no more than 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.
32. An electrode comprising a particulate material according to claim 21 in electrical contact with a current collector.
33. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode according to claim 32 ;
(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.