DESIGN AND FABRICATION OF ELECTRODES WITH GRADIENTS
An electrode has a front face furthest from the current collector and a back face closest to the current collector and Is disposed on the current collector, and the electrode has a primary gradient of one of a chemical, physical and performance properties of the electroactive particle composition between the front and back faces, with the proviso that the primary gradient is not a bulk porosity gradient. In some embodiments, the electrode further comprises one or more secondary gradients Imposed over the primary gradient. The secondary gradient is one or more gradients selected from the group consisting of particle size gradient, particle size distribution gradient, particle morphology gradient, particle internal porosity, bulk porosity, particle volumetric charge-transfer resistance gradient, particle specific surface area gradient, particle crystalline structure gradient, particle crystallite size gradient, particle chemical composition gradient, particle robustness to cycling gradient, binder gradient, conductive additive gradient, and combinations thereof.
1 . An electrode assembly comprising:
a current collector; and
an electrode having a front face furthest from the current collector and a back face closest to the current collector disposed on the current collector, wherein the electrode has a primary gradient of one of a chemical, physical and performance properties of the electroactive particle composition between the front and back faces, with the proviso that the primary gradient is not a bulk porosity gradient.
2 . The electrode assembly of claim 1 , wherein said primary gradient is selected from the group consisting of particle size gradient, particle size distribution gradient, particle morphology gradient, particle internal porosity gradient, particle volumetric charge-transfer resistance gradient, particle specific surface area gradient, particle crystalline structure gradient, particle crystallite size gradient, particle chemical composition gradient, and particle robustness to cycling gradient.
3 . The electrode assembly of claim 1 , wherein the primary gradient comprises a continuous or stepwise change of electrode composition.
4 . (canceled)
5 . The electrode assembly of claim 3 , wherein the electrode comprises a plurality of layers with different electrode compositions.
6 . An electrode with a compositional gradient on a current collector, comprising:
a first type electroactive particles at a front side of the electrode further from a current collector; and
a second type electroactive particles at a back side of the electrode closer to the current collector;
wherein
the compositions of the first type particles and the second type particles form a particle compositional gradient changing from the font side of the electrode to the back side of the electrode; and
the compositional gradient comprises at least one gradient of particle size, particle porosity, particle morphology, particle power characteristics, particle specific surface area, particle crystalline structure, particle crystallite size, amount of conductive additive in a particle layer, or amount of binder in a particle layer.
7 . The electrode assembly of claim 1 or 6 , wherein the electrode further comprises one or more secondary gradients.
8 . The electrode assembly of claim 7 , wherein the secondary gradient is one or more gradients selected from the group consisting of particle size gradient, particle size distribution gradient, particle morphology gradient, particle internal porosity, bulk porosity, particle volumetric charge-transfer resistance gradient, particle specific surface area gradient, particle crystalline structure gradient, particle crystallite size gradient, particle chemical composition gradient, particle robustness to cycling gradient, binder gradient, conductive additive gradient, and combinations thereof.
9 . The electrode assembly of claim 1 or 6 , wherein the electrode comprises a particle volumetric charge transfer resistance gradient wherein the volumetric charge-transfer resistance of the electrode particles increases from the front face to the back face of the electrode.
10 . The electrode assembly of claim 9 , wherein the electrode comprises synthetic carbon, hard carbon, or a combination thereof at a first location, and natural graphite, high-capacity synthetic carbon, or a combination thereof at a second location, wherein the second location is closer to the current collector than the first location.
11 . (canceled)
12 . The electrode assembly of claim 1 or 6 , wherein the electrode comprises a carbon material with a d(002) lattice spacing of more than 3.36 Å at a first location and a carbon material with a d(002) lattice spacing of less than 3.36 Å at a second location, wherein the second location is closer to the current collector than the first location.
13 . The electrode assembly of claim 1 or 6 , wherein the electrode comprises a particle size gradient, a particle morphology gradient, a particle specific surface area gradient, a particle internal porosity gradient.
14 . (canceled)
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20 . The electrode assembly of claim 7 , wherein the electrode comprises a particle size gradient and a porosity gradient.
21 . (canceled)
22 . The electrode assembly of claim 7 , wherein the electrode comprises a particle volumetric charge-transfer resistance gradient and a porosity gradient.
23 . (canceled)
24 . The electrode assembly of claim 7 , wherein the electrode comprises a particle specific surface area gradient and a porosity gradient.
25 . (canceled)
26 . The electrode assembly of claim 7 , wherein the electrode comprises a particle volumetric charge-transfer resistance gradient and a particle specific surface area gradient.
27 . (canceled)
28 . The electrode assembly of claim 7 , wherein the electrode comprises a particle volumetric charge-transfer resistance gradient, a particle specific surface area gradient, and a porosity gradient.
29 . (canceled)
30 . The electrode assembly of claim 7 , wherein the electrode comprises a particle size gradient, a particle specific surface area gradient, and a porosity gradient.
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46 . An electrode with graded porosity on a current collector, comprising:
a first type electroactive particles at a front side of the electrode further from a current collector; and
a second type electroactive particles at a back side of the electrode closer to the current collector;
wherein
the first type electroactive particles have smaller particle sizes than the second type electroactive particles; and
the electrode has a graded porosity which is higher at positions at the front side of the electrode and lower at positions at the back side of the electrode.
47 . The electrode of claim 46 , wherein the graded porosity comprises a continuous porosity gradient comprising a continuous or stepwise change of particle porosity from the front side to the back side.
48 . (canceled)
49 . The electrode of claim 47 , wherein the electrode comprises a plurality of layers of electroactive particles with different porosities, wherein the layer further away from the current collector has porosity higher than the layer closer to the current collector.