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 2 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 50 particle diameter of no more than 7 μm and a particle size span ((D 90 −D 10 )/D 50 ) of 5 or less.
2. A particulate material according to claim 1 , wherein P 1 has a value of 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 1.5 nm.
5. A particulate material according to claim 1 , wherein the PD 90 pore diameter of the porous carbon framework is no more than 10 nm.
6. 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 2.5 to 20 nm.
7. 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 .
8. 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.
9. A particulate material according to claim 1 , wherein the composite particles have a D 90 particle diameter of no more than 10 μm.
10. 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.
11. A particulate material according to claim 1 , wherein the composite particles have a particle size span ((D 90 −D 10 )/D 50 ) of 4 or less.
12. A particulate material according to claim 1 , wherein the fill factor of the silicon in the porous carbon framework is no more than 55%.
13. 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.
14. 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 .
15. 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.
16. A particulate material according to claim 1 , having specific capacity on lithiation of 1200 to 2340 mAh/g.
17. An electrode comprising a particulate material as defined in claim 1 in electrical contact with a current collector.
18. A rechargeable metal-ion battery comprising:
an anode, wherein the anode comprises an electrode as described in claim 17 ;
(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.
19. 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 90 pore diameter as measured by gas adsorption is no more than 10 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 50 particle diameter of no more than 7 μm and a particle size span ((D 90 −D 10 )/D 50 ) of 5 or less.
20. 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 2 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.