Electroactive materials for metal-ion batteries
This invention relates to particulate electroactive materials consisting of a plurality of composite particles, wherein the composite particles comprise: (a) a porous carbon framework including micropores and mesopores having a total volume of 0.4 to 0.75 cm 3 /g, wherein the micropore volume fraction is in the range of 0.5 to 0.85 based on the total volume of micropores and mesopores; and (b) silicon located at least within the micropores of the porous carbon framework in a defined amount relative to the volume of the micropores and mesopores.
1. A particulate material consisting of 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 of P 1 cm 3 /g, wherein P 1 represents a dimensionless number having a value of from 0.4 to 0.75, as measured by nitrogen gas adsorption at 77 K using quenched solid density functional theory (QSDFT) in accordance with ISO 15901-2 and ISO 15901-3, and
wherein the micropore volume fraction is in the range of 0.5 to 0.85, based on the total volume of micropores and mesopores; and
(b) a plurality of nanoscale elemental silicon domains located within the pores of the porous carbon framework;
wherein the weight ratio of silicon to the porous carbon framework in the composite particles is in the range of from [0.9×P 1 to 1.9×P 1 ]:1.
2. A particulate material according to claim 1 , wherein the micropore volume fraction is in the range of 0.55 to 0.85 and wherein the weight ratio of silicon to the porous carbon framework in the composite particles is in the range of from [0.9×P 1 to 1.8×P 1 ]: 1.
3. A particulate material according to claim 1 , wherein P 1 has a value in the range from 0.42 to 0.72.
4. A particulate material according to claim 1 , wherein the micropore volume fraction is in the range from 0.55 to 0.84.
5. A particulate material according to claim 1 , wherein the having a PD 90 pore diameter of up to 20 nm.
6. A particulate material according to claim 1 , wherein the weight ratio of silicon to carbon is in the range from [1×P 1 to 1.8×P 1 ]: 1.
7. A particulate material according to claim 1 , the porous carbon framework having an internal pore volume, wherein at least 80 wt % of the silicon in the composite particles is located within the internal pore volume of the porous carbon framework.
8. A particulate material according to claim 1 , wherein the composite particles have one or more of:
(i) a D 50 particle diameter in the range of 1 μm to 30 μm;
(ii) a D 10 particle diameter of at least 0.5 μm;
(iii) a D 90 particle diameter of up to 50 μm; and
(iv) a particle size distribution span of 5 or less.
9. A particulate material according to claim 1 , wherein the composite particles have a BET surface area of up to 100 m 2 /g.
10. A particulate material according to claim 1 , wherein the volume of micropores and mesopores of the composite particles, in the presence of the silicon, as measured by nitrogen gas adsorption, is up to 0.15×P 1 cm 3 /g.
11. A composition comprising a particulate material according to claim 1 and at least one other component.
12. A composition according to claim 11 , the at least one other component comprising at least one of:
(i) a binder; and
(ii) one or more conductive additives.
13. A composition comprising at least 50 wt % of a particulate material according to claim 1 , based on the total dry weight of the composition.
14. A composition comprising from 15 to 60 wt % of a particulate material according to claim 1 , based on the total dry weight of the composition, and at least one additional particulate electroactive material.
15. A composition according to claim 14 , wherein the at least one additional particulate electroactive material is selected from graphite, hard carbon, silicon, tin, germanium, aluminium and lead.
16. An electrode comprising a particulate material according to claim 1 in electrical contact with a current collector.
17. A rechargeable metal-ion battery comprising:
(i) an anode, wherein the anode comprises an electrode according to claim 16 ;
(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.