Melanin Cathode for Multivalent Ion Insertion Kinetics

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Solution Overview

Problem

Current cathode materials for secondary multivalent batteries face challenges in achieving rapid and reversible insertion/extraction kinetics of multivalent ions, leading to low round-trip voltage efficiency and limited cycling stability, particularly for magnesium (Mg) batteries.

Innovation Solution

The use of catechol-bearing melanin as a cathode material in an electrochemical cell, which facilitates reversible reduction and oxidation of quinone to catechol through insertion and extraction of multivalent cations like Mg2+, utilizing an aqueous electrolyte solution to transport these ions, thereby enhancing charge storage capacity and cycling stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional cathode materials are used for multivalent batteries, then rapid and reversible insertion of lithium ions is achieved, but reasonable charge storage capacities and cycling stability are not achieved

Engineering Contradiction:

Improveinsertion kineticsVSAvoidcycling stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the cathode material by using melanin with specific catechol groups that can reversibly bind multivalent cations. The catechol groups undergo redox reactions (oxidation state changes) that enable rapid and reversible insertion/extraction of Mg2+ ions, achieving both fast kinetics and stable cycling over 500+ cycles with capacity retention above 60 mAhg−1

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs melanin as a composite cathode material that combines organic polymeric structure with redox-active catechol groups. This composite approach allows the material to exhibit both rapid ion transport properties and long-term structural stability, resolving the contradiction between insertion speed and cycling durability

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If conventional cathode materials are used for multivalent batteries, then charge storage capacity is achieved, but round-trip voltage efficiency is reduced due to sluggish insertion kinetics

Engineering Contradiction:

Improvecharge storage capacityVSAvoidredox polarization

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent modifies the electrochemical parameters of the cathode by utilizing melanin's catechol groups that facilitate rapid two-electron transfer reactions. This reduces polarization losses during charge-discharge cycles, achieving high round-trip voltage efficiency while maintaining substantial charge storage capacity of 60 mAhg−1 or more

Inventive Principle:

Principle #35Parameter changes

3Reliability

If melanin cathode is used to achieve rapid and reversible multivalent ion insertion, then charge storage capacity and cycling stability are improved, but electrode material complexity increases

Engineering Contradiction:

Improvecycling stabilityVSAvoidelectrode material complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes melanin's inherent redox-active catechol groups that automatically perform the ion binding and electron transfer functions. The material self-regulates its oxidation state during cycling, converting between catechol and quinone forms without requiring external intervention or complex structural engineering, thereby achieving high cycling stability with relatively simple material composition

Inventive Principle:

Principle #25Self-service

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 catechol-mediated electrochemical cell achieves stable charge storage capacity greater than 60 mAhg−1 over 500 cycles with high coulombic efficiency, reducing redox polarization and improving the cycle stability of multivalent batteries.

Implementation Method 1

an aqueous electrolyte solution in which the anode and the cathode are disposed, wherein the aqueous electrolyte solution is configured to transport the multivalent cations between the anode and the cathode

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

The cathode is configured to reversibly reduce the quinone to the catechol by an insertion of the multivalent cation during the discharge process and oxidize a catechol of the catechol-bearing melanin into a quinone by an extraction of the multivalent cation during a recharge process

Methodology Applied

Scientific EffectRedox reactions: Redox Reactions

Implementation Method 3

Methodology Applied

Scientific EffectRedox reactions: Redox Reactions

Data Source

PatentUS10326139B2Electrochemical cell with melanin electrode

Publication Date: 2019.06.18 CARNEGIE MELLON UNIV

AI summary

An electrochemical cell includes an anode configured to produce multivalent cations during a discharge process, and a cathode comprising a catechol-bearing melanin. The cathode is configured to reversibly oxidize a catechol of the catechol-bearing melanin into a quinone by an extraction of the multivalent cation during a recharge process and reduce the quinone to the catechol by an insertion of the multivalent cation during the discharge process. The electrochemical cell includes an aqueous electrolyte solution in which the anode and the cathode are disposed, wherein the aqueous electrolyte solution is configured to transport the multivalent cations between the anode and the cathode.