ELECTROPHORETIC ASSEMBLY OF ELECTROCHEMICAL DEVICES
Methods are provided for making bipolar electrochemical devices, such as batteries, using electrophoresis. A bipolar device is assembled by applying a field that creates a physical separation between two active electrode materials, without requiring insertion of a discrete separator film or electrolyte layer.
1 . A device, comprising:
a first terminal and a second terminal having a different electrical potential than the first terminal; and
a continuous bridge of conductive particles comprising an electroactive material between the first and second terminals.
2 . The device of claim 1 , wherein the first terminal has a positive polarity and the second terminal has a negative polarity.
3 . The device of claim 1 , wherein the electroactive material comprises carbon.
4 . The device of claim 1 , wherein the electroactive material comprises at least one lithium intercalation compound.
5 . The device of claim 1 , wherein at least some of the particles are coated with conductive material.
6 . The device of claim 1 , comprising:
a third terminal proximate the second terminal;
a fourth terminal; and
a second continuous bridge of conductive particles comprising a second electroactive material between the third and fourth terminals.
7 . The device of claim 1 , wherein the first terminal comprises a metal.
8 . The device of claim 7 , wherein the second terminal comprises a metal.
9 . The device of claim 1 , wherein the second terminal has a longitudinal axis that is substantially parallel to a longitudinal axis of the first terminal.
10 . A method of making an electrode comprising:
providing a first terminal;
providing conductive particles of an electroactive material in a medium;
providing a second terminal;
applying an electrical potential between the first and the second terminal to deposit conductive particles of the electroactive material at the first terminal thereby forming an electronically continuous electrode;
forming a continuous bridge of conductive particles of the electroactive material between the first and second terminals; and
removing the applied electrical potential.
11 . The method of claim 10 , further comprising:
providing a third terminal;
providing conductive particles of a second electroactive material in a medium;
providing a fourth terminal;
applying an electrical potential between the third and the fourth terminals to deposit conductive particles of the second electroactive material at the third terminal thereby forming a second electronically continuous electrode;
forming a second continuous bridge of conductive particles of the second electroactive material between the third and fourth terminals; and
removing the applied electrical potential.
12 . An electrode made by the method of claim 10 .
13 . A battery comprising:
a substrate;
a first terminal;
a second terminal; and
a localized conductive region comprising electroactive material formed on the substrate and surrounded by an insulating region,
wherein at least one of the first or second terminals is electronically connected to the conductive region.
14 . The battery of claim 13 , wherein the localized conductive region has an area of less than 100 nanometers squared.
15 . The battery of claim 13 , having a volume of less than 1 cubic millimeter.