Negative electrode for a lithium-ion electrochemical cell and method of forming same
A method of forming an electrode includes attaching a tab to a collector to form a pre-tabbed current collector; disposing the pre-tabbed current collector onto a non-stick substrate to form a workpiece; and casting a slurry onto the workpiece to form a film. The slurry includes an active material component, one or more carbon additives, and at least one of a filamentary copper additive and a dendritic copper additive. The method includes drying the film at a first temperature to form a dried film; curing the dried film under pressure at a second higher temperature to form a cured film; removing the cured film from the non-stick substrate to form a precursor film; and carbonizing and annealing the precursor film at a third higher temperature. Carbonizing forms a three-dimensional electrically-conductive network and annealing forms a second contiguous network of copper connected to the active material component to form the electrode.
1. A method of forming a negative electrode for a lithium-ion electrochemical cell, the method comprising:
attaching a tab formed from nickel to a current collector formed from a copper matrix to form a pre-tabbed current collector;
disposing the pre-tabbed current collector onto a non-stick substrate including polytetrafluoroethylene to form a workpiece;
casting a slurry onto the workpiece to form a film disposed on the pre-tabbed current collector, wherein the slurry includes:
an active material component;
one or more carbon additives; and
at least one of a filamentary copper additive and a dendritic copper additive;
drying the film at a first temperature to form a dried film;
curing the dried film under pressure at a second temperature that is higher than the first temperature to form a cured film;
removing the cured film from the non-stick substrate to form a precursor film; and
carbonizing and annealing the precursor film at a third temperature that is higher than the second temperature;
wherein carbonizing forms a three-dimensional electrically-conductive network and annealing forms a contiguous network of copper connected to the active material component to thereby form the negative electrode.
2. The method of claim 1 , further including annealing the three-dimensional electrically-conductive network at a fourth temperature that is higher than the third temperature.
3. The method of claim 1 , wherein annealing includes wicking molten copper through the three-dimensional electrically-conductive network.
4. The method of claim 1 , wherein the three-dimensional electrically-conductive network is a first contiguous network of carbon connected to the active material component.
5. The method of claim 1 , wherein attaching is prior to annealing.
6. The method of claim 5 , further including preserving a structural integrity of the tab.
7. The method of claim 1 , wherein disposing does not include supporting the pre-tabbed current collector on a metal foil.
8. The method of claim 1 , wherein drying includes heating the film to the first temperature of from 50° C. to 150° C.
9. The method of claim 8 , wherein drying further includes heating the film under a vacuum.
10. The method of claim 1 , wherein curing includes heating the dried film to the second temperature of from 200° C. to 400° C.
11. The method of claim 1 , wherein carbonizing includes heating the precursor film to the third temperature of from 600° C. to 900° C.
12. The method of claim 2 , wherein annealing includes heating the three-dimensional electrically-conductive network to the fourth temperature of from 900° C. to 1,300° C.
13. The method of claim 1 , wherein annealing includes removing native silicon dioxide from the three-dimensional electrically-conductive network.
14. The method of claim 1 , further including continuously casting the slurry, continuously drying the film, continuously curing the dried film, continuously removing the cured film, and continuously carbonizing and continuously annealing the precursor film.
15. A negative electrode for a lithium-ion electrochemical cell, the negative electrode comprising:
a pre-tabbed current collector including:
a current collector formed from a copper matrix; and
a tab attached to the current collector and formed from nickel; and
a cured composite material disposed on the pre-tabbed current collector and formed from a slurry including:
an active material component;
one or more carbon additives; and
at least one of a filamentary copper additive and a dendritic copper additive;
wherein the cured composite material includes:
a first contiguous network of carbon connected to the active material component; and
a second contiguous network of copper connected to the active material component.
16. The negative electrode of claim 15 , wherein the filamentary copper additive includes microfilament copper.
17. The negative electrode of claim 15 , wherein the dendritic copper additive includes dendritic copper powder.
18. The negative electrode of claim 15 , wherein the at least one of the filamentary copper additive and the dendritic copper additive is present in the slurry in an amount of from 5 parts by weight to 50 parts by weight based on 100 parts by weight of the slurry.
19. A lithium-ion electrochemical cell comprising the negative electrode of claim 15 ; a positive electrode spaced apart from the negative electrode; and an electrolyte solution-filled separator disposed between the positive electrode and the negative electrode.
20. A device comprising the lithium-ion electrochemical cell of claim 19 .