Electroactive materials for metal-ion batteries

1. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:

(a) a porous carbon framework comprising micropores and/or mesopores, wherein

the micropores and/or 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 0.7, and

the PD 50 pore diameter as measured by gas adsorption is no more than 5 nm; and

(b) a plurality of nanoscale 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 [0.5×P 1 to 1.3×P 1 ]:1; and

the particulate material has a Z value of no more than 10% as determined by TGA analysis in air, in which Z=1.875×[(M f −M 800 )/M f ]×100%, in which Mis the mass of the TGA sample at completion of oxidation and M 800 is the mass of the TGA sample at 800° C.

2. A particulate material according to claim 1 , wherein P 1 has a value of at least 0.75.

3. A particulate material according to claim 1 , wherein P 1 has a value of no more than 2.2.

4. A particulate material according to claim 1 , wherein the PD 50 pore diameter of the porous carbon framework is no more than 3 nm.

5. A particulate material according to claim 1 , wherein the PD 70 pore diameter of the porous carbon framework is no more than 5 nm.

6. A particulate material according to claim 1 , wherein the PD 95 pore diameter of the porous carbon framework is no more than 20 nm.

7. A particulate material according to claim 1 , wherein the porous carbon framework has a monomodal pore size distribution.

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 1 , 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 5 to 50 nm.

10. A particulate material according to claim 1 , wherein the porous carbon framework further 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 the weight ratio of silicon to the porous carbon framework is in the range from [0.55×P 1 to 1.1×P 1 ]:1.

12. A particulate material according to claim 1 , wherein at least a portion of the micropores and/or mesopores comprise void space that is fully enclosed by the silicon.

13. A particulate material according to claim 1 , 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.

14. A particulate material according to claim 1 , wherein Z is no more than 5%.

15. 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.

16. A particulate material according to claim 1 , wherein the composite particles have a D 10 particle diameter of at least 0.2 μm and a D 90 particle diameter of no more than 80 μm.

17. A particulate material according to claim 1 , wherein the composite particles have a particle size distribution span of 5 or less.

18. 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 300 m 2 /g.

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 , having specific capacity on lithiation of 1200 to 2340 mAh/g.

21. 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 material.

22. An electrode comprising a particulate material according to claim 1 in electrical contact with a current collector.

23. A rechargeable metal-ion battery comprising:

(i) an anode, wherein the anode comprises an electrode according to claim 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.

24. A particulate material comprising a plurality of composite particles, wherein the composite particles comprise:

(a) a porous carbon framework comprising micropores and/or mesopores, wherein

the micropores and/or 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 0.7, and

the PD 70 pore diameter as measured by gas adsorption is no more than 3 nm; and

(b) a plurality of nanoscale 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 [0.5×P 1 to 1.3×P 1 ]:1;

the particulate material has a Z value of no more than 10% as determined by TGA analysis in air, in which Z=1.875×[(M f −M 800 )/M f ]×100%, in which M f is the mass of the TGA sample at completion of oxidation and M 800 is the mass of the TGA sample at 800° C.; and

the composite particles have a BET surface area of no more than 30 m 2 /g.

25. A particulate material according to claim 24 , wherein the PD 70 pore diameter as measured by gas adsorption is no more than 2 nm.

26. A particulate material according to claim 24 , wherein the PD 80 pore diameter as measured by gas adsorption is no more than 2 nm, and Z is no more than 5%.

27. A particulate material according to claim 24 , wherein:

the porous carbon framework comprises amorphous carbon;

the total volume of macropores in the porous carbon framework is P 2 cm 3 /g, wherein P 2 is no more than 0.1×P 1 ;

the silicon is amorphous silicon; and

the specific capacity of the particulate material on lithiation is 1200 to 2340 mAh/g.