Redox Flow Battery with CO2-Based Redox Couple
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Solution Overview
Problem
Current redox flow batteries lack efficient energy storage and generation capabilities, particularly for intermittent clean energy sources like solar and wind, due to limitations in chemistry and design.
Innovation Solution
A redox flow battery utilizing a carbon dioxide-based redox couple with a bi-functional catalyst for reducing CO2 to carbonaceous derivatives during charging and oxidizing them during discharge, combined with various redox couples at the positive electrode, such as bromine-bromide or vanadium (IV)-vanadium (V), to achieve efficient energy storage and generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional redox couples (vanadium-vanadium, iron-chromium, etc.) are used in redox flow batteries, then the batteries can operate with established chemistry, but the energy storage and generation capabilities are insufficient for intermittent clean energy sources
Solution Approach 1:
The patent changes the chemical parameters by introducing a CO2-based redox couple with a bi-functional catalyst that enables reversible CO2 reduction to formic acid and formic acid oxidation back to CO2. This chemical parameter change provides the necessary adaptability for intermittent energy storage while maintaining reliable electrochemical reactions.
Solution Approach 2:
The patent employs a bi-functional catalyst that combines multiple catalytic activities (CO2 reduction and formic acid oxidation) into a single material system. This composite catalyst approach enables the battery to handle both charging and discharging reactions efficiently, improving reliability for intermittent energy applications.
2Loss of energy
If a bi-functional catalyst is used to reduce CO2 and oxidize formic acid at the negative electrode, then round-trip efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The patent merges the CO2 reduction catalyst and formic acid oxidation catalyst into a single bi-functional catalyst system at the negative electrode. This consolidation reduces the number of separate components needed while maintaining high round-trip efficiency by enabling both half-reactions to occur on the same electrode with a single catalyst material.
Solution Approach 2:
The bi-functional catalyst performs multiple functions: it catalyzes both the reduction of CO2 to formic acid during charging and the oxidation of formic acid back to CO2 during discharging. This multi-functionality reduces energy losses by eliminating the need for separate catalyst systems and reduces device complexity by using a single universal catalyst.
3Quantity of substance
If CO2-based redox couple is implemented with bi-functional catalyst, then operational energy density is enhanced, but the manufacturing and system design complexity increases
Solution Approach 1:
The patent changes the operational parameters by using CO2 (a gas) as the energy storage medium instead of conventional liquid electrolytes. This parameter change significantly increases the operational energy density because CO2 can be stored at high concentrations and the bi-functional catalyst enables efficient conversion between CO2 and formic acid, but it complicates the manufacturing process requiring specialized gas handling and catalyst integration.
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
The battery provides efficient energy storage and generation, addressing the challenges of intermittent clean energy sources by utilizing reversible redox reactions involving carbon dioxide and its derivatives, enhancing round-trip efficiency and operational energy density.
Implementation Method 1
a bi-functional catalyst selected to reduce carbon dioxide to a carbonaceous derivative in an energy storage cycle
Implementation Method 2
a bi-functional catalyst selected to reduce carbon dioxide to a carbonaceous derivative in an energy storage cycle and to oxidize the carbonaceous derivative to carbon dioxide in an energy generation cycle
Implementation Method 3
The ion conducting separator is positioned to conduct ions between the negative and positive electrodes
Implementation Method 4
The reactant species shuttle between high and low oxidation states as required by the battery charge and discharge electrode reactions
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
A redox flow battery where the negative electrode uses carbon dioxide based redox couples. The negative electrode contains a bifunctional catalyst that allows for the reduction of carbon dioxide to carbonaceous species (e.g., formic acid, oxalic acid or their salts) in the battery charge (i.e., energy storage) mode, and for the oxidation of the above-mentioned carbonaceous species in the battery discharge (i.e., energy generation) mode. The positive electrode of the battery can utilize a variety of redox couples including but not restricted to bromine-bromide, chlorine-chloride, vanadium (IV)- vanadium (V), chromium (III)-dichromate (VII), cerium (III) – cerium (IV), oxygen – water (or hydroxide).