Three-chamber electrolytic cell internals for pH gradient control

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Solution Overview

Problem

Existing electrolysis cells with solid-state electrolytes like NaSICON face challenges due to pH gradients forming in the middle chamber during electrolysis, leading to damage and reduced long-term stability, as well as inefficient use of reactants and increased voltage demands.

Innovation Solution

Incorporating internals such as mesh-like wire baskets or glass/plastic beads in the middle chamber to induce turbulence and prevent pH gradient formation, while routing liquid from the middle chamber into the anode chamber through a connection, thereby maintaining a stable pH and protecting the solid-state electrolyte.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a three-chamber electrolysis cell with solid-state electrolyte (e.g., NaSICON) is used to produce alkali metal alkoxides, then the production process can be carried out with separation of chambers, but a concentration gradient forms in the middle chamber leading to locally lowered pH values that damage the solid-state electrolyte

Engineering Contradiction:

Improvelong-term stability of solid-state electrolyteVSAvoidpH gradient formation causing damage to electrolyte

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a dynamic flow system where the electrolyte in the middle chamber is continuously circulated through a connection to the anode chamber. This dynamic circulation prevents the formation of static concentration gradients and maintains relatively uniform pH distribution, thereby protecting the solid-state electrolyte from acid damage while preserving the three-chamber separation benefits

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses the middle chamber as an intermediary zone between the cathode and anode chambers. By connecting the middle chamber to the anode chamber and allowing electrolyte circulation, it acts as a buffer that prevents direct contact between the cathode chamber contents and the anode chamber, while also preventing pH gradient formation that would damage the solid-state electrolyte separating the middle and cathode chambers

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the middle chamber is connected to the anode chamber through a connection for liquid routing, then the pH can be stabilized and electrolyte protected, but the device complexity increases

Engineering Contradiction:

Improvestability of pH and protection of electrolyteVSAvoidstructural complexity of chamber connections

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the middle chamber and anode chamber into a closely integrated system through a direct connection for liquid routing. This connection allows the electrolyte to flow between chambers while maintaining their functional separation, achieving pH stabilization without requiring complex external control systems or multiple separate components

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances the longevity of the solid-state electrolyte by preventing pH gradients, reducing reactant consumption, and maintaining a stable process, thus improving the efficiency and durability of the electrolysis cell.

Implementation Method 1

The cathode chamber and the anode chamber are separated by a ceramic that conducts the alkali metal ion used, for example NaSICON

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

The middle chamber is separated from the anode chamber by a diffusion barrier

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 3

The internals result in vortexing of the electrolyte solution as it flows through the middle chamber during the electrolysis

Methodology Applied

Scientific EffectTurbulence: Turbulence

Data Source

PatentUS20240337029A1Three-chamber electrolytic cell for the production of alkali metal alkoxides

Publication Date: 2024.10.10 EVONIK OPERATIONS GMBH

AI summary

The present invention relates, in a first aspect, to an electrolysis cell having three chambers, wherein the middle chamber is separated from the cathode chamber by a solid-state electrolyte permeable to cations, for example NaSICON, and from the anode chamber by a diffusion barrier. The invention is characterized in that the middle chamber comprises internals.The electrolysis cell according to the invention solves the problem that a concentration gradient forms in the middle chamber of the electrolysis cell during the electrolysis, which leads to locally lowered pH values and hence to damage to the solid-state electrolyte. The internals result in vortexing of the electrolyte solution as it flows through the middle chamber during the electrolysis, which prevents the formation of a pH gradient.In a second aspect, the present invention relates to a process for producing an alkali metal alkoxide solution in the electrolysis cell according to the invention.