Potassium Ion Battery Positive Electrode Active Material KnMOm
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Solution Overview
Problem
Potassium ion secondary batteries have a lower theoretical capacity due to potassium's large atomic weight and ionic radius, and existing positive electrode active materials like Prussian blue have low capacity and are not effective.
Innovation Solution
A potassium compound with a specific composition, KnMOm, where M is copper, iron, or manganese, is used as a positive electrode active material, enabling high potential and high theoretical charge-discharge capacity, and can be synthesized with an orthorhombic or monoclinic structure and controlled particle diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Prussian blue is used as positive electrode active material, then the battery can operate, but the charge capacity is low (theoretical charge capacity: about 85 mAhg−1; effective capacity: 65 mAhg−1)
Solution Approach 1:
The invention changes the chemical composition parameters by using a specific compound formula KnMOm where M is copper, iron, or manganese, with n=0.5 to 3.5 and m=1.5 to 2.5. This parameter change transforms the low-capacity Prussian blue system into a high-capacity potassium compound system with theoretical charge capacity exceeding 200 mAhg−1, directly resolving the capacity limitation while maintaining manufacturability through controlled synthesis conditions.
2Ease of manufacture
If potassium ion secondary battery is developed, then resource and cost advantages are achieved, but the theoretical capacity is lower than lithium ion secondary battery due to large atomic weight and ionic radius
Solution Approach 1:
The invention employs composite material design by combining potassium with transition metals (copper, iron, or manganese) in specific stoichiometric ratios to form KnMOm compounds. This composite approach leverages the resource advantages of potassium while the transition metal components provide high-capacity pathways, achieving theoretical charge capacity >200 mAhg−1 and effectively compensating for the inherent capacity limitations of potassium.
3Quantity of substance
If high capacity positive electrode active material is sought, then alternative materials to Prussian blue must be found, but effective materials have not been available
Solution Approach 1:
The invention applies local quality by selecting specific transition metals (copper, iron, or manganese) with particular properties to substitute in the KnMOm structure. This localized material selection optimizes the electronic and structural properties of the positive electrode active material, enabling high capacity while maintaining structural stability and electrochemical performance, thus providing versatile alternatives to Prussian blue.
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 potassium ion secondary battery using this active material achieves high capacity and potential, allowing for the use of low-cost aluminum as a negative electrode current collector instead of expensive copper.
Implementation Method 1
the method comprising a heating step of heating a mixture containing potassium, oxygen, and copper, iron, or manganese
Implementation Method 2
heating a mixture containing potassium, oxygen, and copper, iron, or manganese
Data Source
AI summary
By using a potassium ion secondary battery positive electrode active material comprising a potassium compound represented by general formula (1): KnMOm, wherein M is copper or iron, n is 0.5 to 3.5, and m is 1.5 to 2.5, provided is a potassium ion secondary battery positive electrode active material having higher theoretical discharge capacity and higher effective capacity than a potassium secondary battery using Prussian blue as a positive electrode active material.