Large-volume-change lithium battery electrodes
A battery electrode material includes: 1) primary particles formed of an electrochemically active material; and 2) a secondary particle defining multiple, discrete internal volumes, wherein the primary particles are disposed within respective ones of the internal volumes.
1. A battery electrode material, comprising:
primary particles formed of Si; and
a secondary particle defining multiple, closed internal volumes,
wherein the secondary particle consists of a homogeneous amorphous composition,
wherein a number of the closed internal volumes is at least 100,
wherein the primary particles are disposed within the closed internal volumes bounded by the homogeneous amorphous composition of the secondary particle,
wherein a single primary particle is disposed within each closed internal volume,
wherein, for at least one cycling state of Si, at least one primary particle occupies less than 100% of a respective closed internal volume to define a void space, such that a ratio of a volume of the void space relative to a volume of the primary particle inside the closed internal volume is between 1:2 and 2.9:1, and the void space is devoid of carbon.
2. The battery electrode material of claim 1 , wherein the secondary particle has an aspect ratio that is less than 10.
3. The battery electrode material of claim 1 , wherein the secondary particle has an outer lateral dimension in the range of 200 nm to 200 μm.
4. The battery electrode material of claim 1 , wherein the secondary particle is formed of carbon.
5. The battery electrode material of claim 1 , wherein the number of the closed internal volumes is at least 1000 or at least 10 4 , and the secondary particle is ionically conductive with respect to Li ions.
6. The battery electrode material of claim 1 , wherein the primary particles are Si nanoparticles.
7. The battery electrode material of claim 1 , wherein at least one primary particle has an aspect ratio that is less than 10.
8. The battery electrode material of claim 1 , wherein at least one primary particle has an outer lateral dimension in the range of 1 nm to 500 nm.
9. The battery electrode material of claim 1 , further comprising a coating of a conductive material covering the secondary particle.
10. The battery electrode material of claim 9 , wherein the coating includes nanoparticles formed of the conductive material.
11. The battery electrode material of claim 9 , wherein the conductive material includes silver, copper, iron, or cobalt.
12. A battery comprising:
an anode;
a cathode; and
an electrolyte disposed between the anode and the cathode,
wherein at least one of the anode and the cathode includes the battery electrode material of claim 1 .
13. The battery electrode material of claim 1 , wherein the ratio of the volume of the void space relative to the volume of the primary particle inside the closed internal volume is at least 1:1.
14. The battery electrode material of claim 1 , wherein the ratio of the volume of the void space relative to the volume of the primary particle inside the closed internal volume is at least 2:1.
15. The battery electrode material of claim 1 , wherein a weight ratio of Si relative to a combined weight of Si and the secondary particle is in a range of 50% to 95%.
16. The battery electrode material of claim 1 , wherein the secondary particle is formed of amorphous carbon.
17. The battery electrode material of claim 1 , wherein the secondary particle includes multiple, interconnected shells that define the closed internal volumes.
18. The battery electrode material of claim 17 , wherein the shells are amorphous carbon shells.
19. The battery electrode material of claim 17 , wherein walls of the shells have a thickness in a range of 1 nm to 100 nm.