Process and apparatus for switching redoxactive cells

Patent metadata

Field	Value
Publication number	US-2020292902-A1
Application number	US-201716082013-A
Country	US
Kind code	A1
Filing date	Mar 7, 2017
Priority date	Mar 7, 2016
Publication date	Sep 17, 2020
Grant date	—

Abstract

Described herein is a process for switching an electrochromic cell including at least a first electrode layer and a second electrode layer. The cell also includes an ion-conducting layer that separates the first and second electrode layers and a temperature sensor for measuring a temperature in or on or in the vicinity of the electrochromic cell. Moreover, a first contact member is electronically connected with the first electrode layer, and a second contact member is electronically connected with the second electrode layer. Furthermore, at least the first electrode layer includes an organic polymer matrix and, dispersed therein, an electrochromic material, electronically conductive nanoobjects, and an electrolyte dissolved in a solvent. Further, the process including measuring the current flowing through the cell if a voltage is applied to the electrode layers, applying a voltage to the contact members, and varying the applied voltage as a function of the current.

First claim

1 . Process for switching an electrochromic cell comprising the following components:
a first electrode layer capable of reversibly inserting ions, a second electrode layer capable of reversibly inserting ions, an ion-conducting layer that separates the first electrode layer and the second electrode layer, a temperature sensor for measuring a temperature (T) in or on or in the vicinity of the electrochromic cell, a first contact member electronically connected with the first electrode layer, a second contact member electronically connected with the second electrode layer, wherein the first and the second electrode layer are counter electrodes to each other, and wherein at least the first electrode layer comprises: an organic polymer matrix, and dispersed within the organic polymer matrix: an electrochromic material, electronically conductive nanoobjects, and an electrolyte dissolved in a solvent, wherein the process comprises the steps of: applying a voltage (U C ) to the first and second contact members and measuring a current (i C ) flowing through the electrochromic cell if the voltage is applied; and varying the applied voltage (U C ) as a function of the cell current (i C ), such that the voltage generated between the first and second electrode layers is kept within predetermined temperature (T) dependent safe redox limits and such that the cell current (i C ) is kept within predetermined temperature-dependent limits, wherein the applied voltage (U C ) is only increased if the cell current (i C ) is less than a maximum cell current (i max ), determined according to:
i max =j max ×Area+( T−T 0 )× F,

where j max is a predetermined maximum current density, Area is the active cell area, T is the temperature of the electrochromic cell measured with the temperature sensor, T 0 is a reference temperature, and F is a factor.

2 . Process according to claim 1 , wherein the current (i C ) flowing through the electrochromic cell is measured in a non-continuous way.

3 . Process according to claim 1 , wherein the applied voltage (U C ) is increased in a linear fashion if the cell current (i C ) is less than the maximum cell current (i max ) and the voltage (U C ) generated between the first and second electrode layers is within predetermined temperature (T) dependent safe redox limits.

4 . Process according to claim 1 , wherein the current (i C ) flowing through the cell is measured over the time for calculating the charge inserted into the first and second electrode layers.

5 . Process according to claim 1 , wherein the applied voltage (U C ) is increased or decreased by a controller depending on measured voltage (U C ) of the first and second contact members.

6 . Process according to claim 1 , further comprising a step of determining a leakage current of the electrochromic cell.

7 . Apparatus for switching an electrochromic cell, wherein the apparatus comprises the following components:
a first electrode layer capable of reversibly inserting ions, a second electrode layer capable of reversibly inserting ions, an ion-conducting layer that separates the first electrode layer and the second electrode layer, a temperature sensor for measuring a temperature (T) in or on or in close vicinity of the electrochromic cell, a first contact member electronically connected with the first electrode layer, a second contact member electronically connected with the second electrode layer, wherein the first and the second electrode layer are counter electrodes to each other, and wherein at least the first electrode layer comprises: an organic polymer matrix, and dispersed within the organic polymer matrix: an electrochromic material, electronically conductive nanoobjects, and an electrolyte dissolved in a solvent, wherein the apparatus further comprises: means for applying a voltage (U C ) to the first and second contact members; a controller connected to the means for applying the voltage (U C ); an ammeter, adapted to measure a cell current (i C ) and to send the measured values of the cell current (i C ) to the controller, wherein the controller is adapted to calculate a magnitude of the electrical voltage (U C ) to be applied to the first and second contact members based on values of the measured temperature (T), electrochromic voltage limits, and the cell current (i C ), wherein the controller is further adapted to increase the applied voltage (U C ) as a function of the cell current (i C ), such that the voltage generated between the first and second electrode layers is kept within predetermined temperature-dependent safe redox limits and such that the cell current (i C ) is kept within predetermined temperature-dependent limits, wherein the controller is further adapted to increase the applied voltage (U C ) only if the cell current (i C ) is less than a maximum cell current (i max ) determined according to
i max =j max ×Area+( T−T 0 )× F,

where j max is a predetermined maximum current density, Area is the active cell area, T is the temperature of the electrochromic cell measured with the temperature sensor, T 0 is a reference temperature, and F is a factor.

8 . Apparatus according to claim 7 , wherein the ammeter is adapted to measure the current (i C ) flowing through the electrochromic cell in a non-continuous way.

9 . Apparatus according to claim 7 , wherein the controller is further adapted to increase the applied voltage (U C ) in a linear fashion, if the cell current (i C ) is less than the maximum cell current (i max ) and the voltage (U C ) generated between the first and second electrode layers is within predetermined temperature dependent safe redox limits.

10 . Apparatus according to claim 7 , wherein the ammeter is further adapted to measure the current (i C ) flowing through the electrochromic cell over the time for calculating the charge inserted into the first and second electrode layers.

11 . Apparatus according to claim 7 , wherein the controller is further adapted to increase or decrease the applied voltage (U C ) depending on a measured voltage (U C ) of the first and second electrode layers.

12 . Apparatus according to claim 7 , wherein the controller is further adapted to determine a leakage current of the electrochromic cell.

13 . Apparatus according to claim 7 , wherein
the electrochromic material is present in the form of nanoobjects.

14 . Apparatus according to claim 7 , wherein
the electronically conductive nanoobjects are nanowires.

15 . Apparatus according to claim 7 , wherein
the first electrode layer is disposed on a first optically transparent electronically conductive layer, and the first contact member contacts the first optically transparent electronically conductive layer, the second electrode layer is disposed on a second optically transparent electronically conductive layer, and the second contact member contacts the second optically transparent electronically conductive layer, the first optically transparent electronically conductive layer is disposed on a first electrically insulating optically transparent substrate, the second optically transparent electronically conductive layer is disposed on a second electrically insulating optically transparent substrate, and the first electrically insulating optically transparent substrate and/or second electrically insulating optically transparent substrate is glass or organic polymer.

16 . Apparatus according to claim 7 , wherein
the first electrode layer is disposed on a first electrically insulating opt

Assignees

• Basf Se

Inventors

• Waldmann Daniel
• Roeder Jens
• Goebel Michael
• Ahlf Maraike

Classifications

• G02F1/163 Primary

  Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor · CPC title

• G02F1/155 Primary

  Electrodes · CPC title

• G02F2202/36

  Micro- or nanomaterials · CPC title

• G02F1/1533

  structural features not otherwise provided for · CPC title

• G02F1/15165

  Polymers · CPC title