Electrodes for aluminum electrolysis cells and methods of making the same

Patent metadata

Field	Value
Publication number	US-2024425378-A1
Application number	US-202418829880-A
Country	US
Kind code	A1
Filing date	Sep 10, 2024
Priority date	Mar 15, 2022
Publication date	Dec 26, 2024
Grant date	—

Abstract

The present disclosure relates to methods of making electrodes for use in electrolysis cells. The method may include forming a TiB 2 feedstock into a predetermined shaped product to realize an appropriate density. The method may also include producing a final shaped product from the predetermined shaped product by exposing the predetermined shaped product to elevated temperature. Due to the exposing step, the final shaped product may have a plurality of pores and may realize one or more properties and/or characteristics.

First claim

What is claimed is:

1 . A method comprising:
(a) forming a TiB 2 feedstock into a predetermined shaped product, wherein the predetermined shaped product realizes a density of from 40% to 70% of a theoretical density of pure TiB 2 ; and (b) producing a final shaped product from the predetermined shaped product;
wherein the producing comprises exposing the predetermined shaped product to elevated temperature, wherein, due to the exposing, the final shaped product realizes a plurality of pores and at least one of the following properties:
(i) a density of from 85% to 98% of the theoretical density of TiB 2 ;
(ii) an average grain size of not greater than 15 micrometers;
(iii) from 1 to 15 vol. % intergranular porosity;
(iv) an average pore size not greater than 120% of the average grain size; and
(v) a random grain orientation.

2 . The method of claim 1 , wherein the TiB 2 feedstock comprises TiB 2 particles, TiB 2 granules, and combinations thereof.

3 . The method of claim 1 , wherein the forming step (a) comprises one or more of pressing, roll compacting, casting, and extruding of the TiB 2 feedstock to form the predetermined shaped product.

4 . The method of claim 1 , wherein the forming step (a) is completed at ambient temperature.

5 . The method of claim 1 , wherein the forming step (a) comprises applying a pressure of at least 5000 psi.

6 . The method of claim 1 , wherein the predetermined shaped product realizes a density of at least 45% of the theoretical density of TiB 2 .

7 . The method of claim 6 , wherein the predetermined shaped product realizes a density of not greater than 68% of the theoretical density of TiB 2 .

8 . The method of claim 1 , wherein the producing step (b) comprises:
first heating the predetermined shaped product at a first temperature and for a first period of time; second heating the predetermined shaped product at a second temperature for a second period of time, wherein the second temperature is higher than the first temperature.

9 . The method of claim 8 , wherein the first temperature is at least 200° C., or at least 300° C., or at least 400° C., or at least 500° C.

10 . The method of claim 8 , wherein the first period of time is from at least 1 minute to not greater than 48 hours.

11 . The method of claim 8 , wherein the second period of time is from at least 1 minute to not greater than 96 hours.

12 . The method of claim 8 , wherein the first heating comprises heating from an initial temperature to the first temperature at a first heating rate, wherein the first heating rate is not greater than 10° C./min.

13 . The method of claim 8 , wherein the second heating comprises heating from the first temperature to the second temperature at a second heating rate, wherein the second heating rate is not greater than 8° C./min.

14 . The method of claim 1 , comprising:
preparing the TiB 2 feedstock for the forming step, wherein the preparing step comprises, prior to the forming step, spray drying a slurry thereby producing TiB 2 granules.

15 . The method of claim 14 , wherein the slurry comprises a liquid medium, wherein due to at least a dispersant and a binder, the TiB 2 granules comprise at least one of:
(i) a D 90 of not greater than 200 micrometers; (ii) a D 10 of at least 10 micrometers; (iii) a bulk density of from 1.0 to 1.8 g/cm 3 ; (iv) a liquid medium content of not greater than 0.5 wt. %; and (v) a flow rate of at least 0.2 g/s.

16 . The method of claim 14 , wherein the preparing step comprises: deagglomerating a first TiB 2 powder to produce a second TiB 2 powder, wherein the second TiB 2 powder realizes at least one of the following:
(i) a D 50 of from 0.5 to 4.0 micrometers; (ii) a surface area of from 1.0 to 3.0 m 2 /g; (iii) not greater than 5.0 wt. % O, or not greater than 4 wt. % O, or not greater than 3 wt. % O, or not greater than 2.5 wt. % O, or not greater than 2.0 wt. % O, or not greater than 1.5 wt. % O, or not greater than 1 wt. % O; (iv) not greater than 5.0 wt. % C, or not greater than 4 wt. % C, or not greater than 3 wt. % C, or not greater than 2.5 wt. % C, or not greater than 2.0 wt. % C, or not greater than 1.5 wt. % C, or not greater than 1 wt. % C; and (v) an irregular particle morphology.

17 . A monolithic shaped titanium diboride (TiB 2 ) product, comprising:
(a) at least 50 vol. % TiB 2 ; (b) at least three of the following properties:
(i) a density of from 85% to 98% of the theoretical density of TiB 2 ;
(ii) an average grain size of not greater than 15 micrometers;
(iii) from 1 to 15 vol. % intergranular porosity;
(iv) an average pore size not greater than 120% of the average grain size; and
(v) a random grain orientation.

18 . The monolithic shaped titanium diboride (TiB 2 ) product of claim 17 , wherein the monolithic shaped titanium diboride (TiB 2 ) product is configured for use in an electrochemical cell.

19 . The monolithic shaped titanium diboride (TiB 2 ) product of claim 18 , wherein the monolithic shaped titanium diboride (TiB 2 ) product comprises the random grain orientation, wherein the random grain orientation is similarly oriented in both a first face and a second face of the monolithic shaped titanium diboride (TiB 2 ) product.

Assignees

• Alcoa Usa Corp

Inventors

• Mcmillen James C
• Sworts Lance M
• Mosser Benjamin D

Classifications

• C25C3/08 Primary

  Cell construction, e.g. bottoms, walls, cathodes · CPC title

• C01P2006/22

  Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability · CPC title

• C01P2006/14

  Pore volume · CPC title

• C01P2006/11

  Powder tap density · CPC title

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title