Electrochemical cells comprising porous structures comprising sulfur
The present invention relates to the use of porous structures comprising sulfur in electrochemical cells. Such materials may be useful, for example, in forming one or more electrodes in an electrochemical cell. For example, the systems and methods described herein may comprise the use of an electrode comprising a conductive porous support structure and a plurality of particles comprising sulfur (e.g., as an active species) substantially contained within the pores of the support structure. The inventors have unexpectedly discovered that, in some embodiments, the sizes of the pores within the porous support structure and/or the sizes of the particles within the pores can be tailored such that the contact between the electrolyte and the sulfur is enhanced, while the electrical conductivity and structural integrity of the electrode are maintained at sufficiently high levels to allow for effective operation of the cell. Also, the sizes of the pores within the porous support structures and/or the sizes of the particles within the pores can be selected such that any suitable ratio of sulfur to support material can be achieved while maintaining mechanical stability in the electrode. The inventors have also unexpectedly discovered that the use of porous support structures comprising certain materials (e.g., metals such as nickel) can lead to relatively large increases in cell performance. In some embodiments, methods for forming sulfur particles within pores of a porous support structure allow for a desired relationship between the particle size and pore size. The sizes of the pores within the porous support structure and/or the sizes of the particles within the pores can also be tailored such that the resulting electrode is able to withstand the application of an anisotropic force, while maintaining the structural integrity of the electrode.
1. An electrode for use in an electrochemical cell, comprising:
a porous support structure comprising a plurality of pores; and
an electrode active material comprising sulfur substantially contained within the pores of the porous support structure, wherein:
each pore of the plurality of pores has a pore volume, and the plurality of pores has a total pore volume defined by the sum of each of the individual pore volumes;
at least about 50% of the total pore volume is occupied by pores having cross-sectional diameters of between about 0.1 microns and about 10 microns, and
the electrode comprises at least about 20 wt % sulfur.
2. An electrode for use in an electrochemical cell, comprising:
a porous support structure comprising a plurality of pores; and
an electrode active material comprising sulfur substantially contained within the pores of the porous support structure, wherein:
the plurality of pores of the porous support structure together defines a total pore volume, and at least about 50% of the total pore volume is defined by pores having cross-sectional diameters of between about 0.1 microns and about 10 microns; and
the electrode comprises at least about 20 wt % sulfur.
3. An electrode as in claim 1 , wherein the porous support structure comprises an electrically conductive material.
4. An electrode as in claim 1 , wherein the porous support structure comprises at least one of carbon, a metal, a polymer, a ceramic, and a semiconductor.
5. An electrode as in claim 1 , wherein the porous support structure comprises carbon.
6. An electrode as in claim 1 , wherein the porous support structure comprises silicon dioxide.
7. An electrode as in claim 1 , wherein the sulfur comprises at least one of elemental sulfur, polymeric sulfur, inorganic sulfides, inorganic polysulfides, organic sulfides, organic polysulfides, and sulfur organic compounds.
8. An electrode as in claim 1 , wherein the sulfur comprises elemental sulfur.
9. An electrode as in claim 1 , wherein the electrode contains less than about 20 wt % binder.
10. A method of making an electrode for use in an electrochemical cell, comprising:
providing a porous support structure comprising a plurality of pores, wherein the plurality of pores of the porous support structure together define a total pore volume, and at least about 50% of the total pore volume is defined by pores having cross-sectional diameters of between about 0.1 microns and about 10 microns; and
depositing an electrode active material comprising sulfur within the pores of the porous support structure,
wherein the electrode comprises at least about 20 wt % sulfur.
11. An electrode as in claim 2 , wherein the porous support structure comprises an electrically conductive material.
12. An electrode as in claim 2 , wherein the porous support structure comprises carbon.
13. An electrode as in claim 2 , wherein the sulfur comprises elemental sulfur.
14. An electrode as in claim 2 , wherein the electrode contains less than about 20 wt % binder.
15. A method as in claim 10 , wherein the porous support structure comprises carbon.
16. A method as in claim 10 , wherein the sulfur comprises elemental sulfur.
17. A method as in claim 10 , wherein the electrode contains less than about 20 wt % binder.