Composite electrodes including embedded porous current collectors and methods of manufacturing the same
A composite electrode for an electrochemical cell that cycles lithium ions may include a metal current collector having a three-dimensional porous structure defining an interconnected network of open pores and an electrode material disposed within the open pores of the current collector. An oxygen-containing reactive layer may be formed on surfaces of the current collector and an electrode precursor mixture may be deposited thereon and dried to form a solid electrode material having a continuous structure within the open pores of the current collector. The electroactive material particles and/or the electrically conductive agent may interact with the oxygen-containing reactive layer on the metal current collector to form an oxygen-containing adhesive layer along an interface between the current collector and the solid electrode material. The electroactive material particles and the electrically conductive agent may be chemically bonded to the current collector via hydrogen bonds within the oxygen-containing adhesive layer.
1 . A method of manufacturing a composite electrode for an electrochemical cell that cycles lithium ions, the method comprising the following steps:
(a) forming an oxygen-containing reactive layer on wall surfaces of a metal current collector having a first side, an opposite second side, and a three-dimensional porous structure defining an interconnected network of open pores extending between the first side and the second side thereof;
(b) depositing an electrode precursor mixture on the wall surfaces of the metal current collector such that the electrode precursor mixture is disposed within the open pores and along the first side and the second side of the metal current collector, the electrode precursor mixture comprising electroactive material particles, an electrically conductive agent, and a solvent, the electrode precursor mixture comprising, by weight, less than 1% of an organic polymer binder, the electrically conductive agent comprising a carbon-based material having oxygen-containing hydrophilic functional groups disposed on a surface thereof; and
(c) drying the electrode precursor mixture to remove the solvent therefrom and form a solid electrode material having a continuous structure and being disposed within the open pores and along the first side and the second side of the metal current collector, the electroactive material particles and the electrically conductive agent being chemically bonded to one another within the solid electrode material via hydrogen bonds that extend around the three-dimensional porous structure of the metal current collector and through the interconnected network of open pores such that the electrode material is retained in physical contact with the metal current collector,
wherein the electroactive material particles and the electrically conductive agent interact with the oxygen-containing reactive layer on the wall surfaces of the metal current collector to form an oxygen-containing adhesive layer along an interface between the wall surfaces of the metal current collector and the solid electrode material, and
wherein the electroactive material particles and the electrically conductive agent are chemically bonded to the wall surfaces of the metal current collector via hydrogen bonds within the oxygen-containing adhesive layer.
2 . The method of claim 1 , wherein the oxygen-containing reactive layer comprises a plurality of -hydroxyl groups, -carboxyl groups, and/or metal oxides covalently bonded to the wall surfaces of the metal current collector, and wherein the oxygen-containing reactive layer is formed on the wall surfaces of the metal current collector:
by heating the metal current collector in an oxygen-containing environment;
by immersing the metal current collector in an aqueous hydroxide solution; or
using an electrochemical anodization technique.
3 . The method of claim 1 , wherein the electrode precursor mixture is deposited on the wall surfaces of the metal current collector over the first side and the second side of the metal current collector such that the metal current collector is encapsulated in the electrode precursor mixture.
4 . The method of claim 1 , wherein the electrode precursor mixture is substantially free of polyvinylidene fluoride, ethylene propylene diene monomer rubber, styrene butadiene rubber, carboxymethyl cellulose, and polyacrylic acid, and wherein the electrode precursor mixture is substantially free of N-methylpyrrolidone.
5 . The method of claim 1 , further comprising:
prior to step (c), forcing the electrode precursor mixture into the open pores of the metal current collector such that the electrode precursor mixture fills the open pores and removing an excess amount of the electrode precursor mixture from the metal current collector by passing the electrode precursor mixture and the metal current collector between a set of plates disposed on opposite sides of the metal current collector and spaced-apart from one another by a gap; and
after step (c), consolidating the electroactive material particles and the electrically conductive agent within the solid electrode material by passing the solid electrode material and the metal current collector between set of rollers disposed on opposite sides of the metal current collector and spaced-apart from one another by a gap.
6 . The method of claim 1 , wherein:
the electroactive material particles comprise a transition metal oxide that can undergo the reversible insertion or intercalation of lithium ions, and wherein the metal current collector comprises aluminum; or
the electroactive material particles comprise silicon, silicon oxide, tin, tin oxide, aluminum, bismuth, antimony, indium, zinc, germanium, germanium oxide, titanium oxide, or a combination thereof, and wherein the metal current collector comprises copper.
7 . A composite electrode for an electrochemical cell that cycles lithium ions, the electrode comprising:
a metal current collector having a first side, an opposite second side, and a three-dimensional porous structure that defines an interconnected network of open pores extending between the first side and the second side thereof, the interconnected network of open pores being defined by walls having wall surfaces that extend between the first side and the second side of the metal current collector;
an electrode material having a continuous structure and being disposed within the open pores and along the first side and the second side of the metal current collector, the electrode material comprising electroactive material particles and an electrically conductive agent, the electrode material comprising, by weight, less than 1% of an organic polymer binder, the electrically conductive agent comprising a carbon-based material having oxygen-containing hydrophilic functional groups disposed on a surface thereof, the electroactive material particles and the electrically conductive agent being chemically bonded to one another within the electrode material via hydrogen bonds that extend around the three-dimensional porous structure of the metal current collector and through the interconnected network of open pores such that the electrode material is retained in physical contact with the metal current collector; and
an oxygen-containing adhesive layer disposed along an interface between the metal current collector and the electrode material, wherein the electrode material is chemically bonded to the wall surfaces of the metal current collector via hydrogen bonds within the oxygen-containing adhesive layer.
8 . The composite electrode of claim 7 , wherein the electroactive material particles and the electrically conductive agent are chemically bonded to the wall surfaces of the metal current collector via hydrogen bonds within the oxygen-containing adhesive layer.
9 . The composite electrode of claim 8 , wherein the electrode material has a continuous structure and extends over the first side and the second side of the metal current collector such that the metal current collector is encapsulated in the electrode material, and wherein the electrode material entirely fills the open pores of the metal current collector.
10 . The composite electrode of claim 9 , wherein the metal current collector is macroporous, the open pores have pore diameters of greater than 50 nanometers, and the metal current collector has a porosity of greater than or equal to 0.5 and less than or equal to 0.99.
11 . The composite electrode of claim 10 , wherein the metal current collector has a thickness of greater than or equal to 1 micrometer and less than or equal to 60 micrometers.
12 . The composite electrode of claim 11 , wherein, during formation of the composite electrode, the electroactive material particles and the electrically conductive agent interact with -hydroxyl groups, -carboxyl groups, and/or metal oxides covalently bonded to the wall surfaces of the metal current collector to form the oxygen-containing adhesive layer.
13 . The composite electrode of claim 12 , wherein the composite electrode comprises, by weight, less than 0.1% polyvinylidene fluoride, ethylene propylene diene monomer rubber, styrene butadiene rubber, carboxymethyl cellulose, polyacrylic acid, and N-methylpyrrolidone.
14 . The composite electrode of claim 13 , wherein the oxygen-containing adhesive layer has a thickness of less than or equal to 15 nanometers.
15 . The composite electrode of claim 13 , wherein the oxygen-containing adhesive layer consists of a single atomic layer of hydrogen bonds between the metal current collector and the electroactive material particles and/or the electrically conductive agent in the electrode material.
16 . The composite electrode of claim 14 , wherein the electroactive material particles comprise a transition metal oxide that can undergo the reversible insertion or intercalation of lithium ions, the metal current collector comprises aluminum, and the oxygen-containing adhesive layer comprises aluminum oxide.
17 . The composite electrode of claim 14 , wherein the electroactive material particles comprise silicon, silicon oxide, tin, tin oxide, aluminum, bismuth, antimony, indium, zinc, germanium, germanium oxide, titanium oxide, or a combination thereof, the metal current collector comprises copper, and the oxygen-containing adhesive layer comprises copper oxide.