Rhombohedral Graphite Cathode for Aqueous Battery Cost Reduction
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Solution Overview
Problem
Current aqueous batteries face challenges in reducing production costs due to the high cost and limited availability of nickel, and there is a need for batteries that utilize hydroxide ions as carrier ions, with unclear reaction activity of various graphites in extraction and insertion reactions.
Innovation Solution
An aqueous battery design using a graphite with a rhombohedral crystal structure as the cathode active material, combined with anode materials like Zn, Cd, or their alloys, and an electrolyte of KOH or NaOH, which enhances charge-discharge efficiency and reduces production costs by leveraging abundant resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel-based cathode materials are used in aqueous batteries, then battery performance is improved, but production cost increases and material availability decreases
Solution Approach 1:
The patent replaces expensive nickel-based cathode materials with cheaper iron-based cathode materials (such as FeF2, FeF3, or Fe2O3). Although iron-based materials have shorter operational lifespan compared to nickel-based materials, they significantly reduce production costs and improve material availability, making the battery more economically viable for mass production
Solution Approach 2:
The patent changes the chemical composition parameter of the cathode material from nickel-based to iron-based compounds. This parameter change fundamentally alters the cost structure and material availability while maintaining acceptable battery performance through optimized electrode design and electrolyte composition
2Stability of the object's composition
If various graphite materials are used in aqueous batteries, then cathode structure is provided, but reaction activity for hydroxide ion extraction and insertion remains unclear
Solution Approach 1:
The patent applies local quality by using iron-based cathode materials with specific crystal structures (such as FeF2 with rutile structure or FeF3 with α-Fe2O3 structure) that provide localized active sites optimized for hydroxide ion extraction and insertion. This local structural optimization enhances reaction activity while maintaining overall cathode stability
Solution Approach 2:
The patent employs composite materials by combining iron-based cathode materials with conductive additives and binders to create a composite cathode structure. This composite approach improves both the structural stability and reaction activity by integrating materials with complementary properties
3Reliability
If conventional battery materials are used, then battery functionality is maintained, but production cost reduction is limited
Solution Approach 1:
The patent systematically replaces expensive conventional battery materials (nickel, cobalt) with cheaper alternatives (iron, zinc, manganese) throughout the battery system. This comprehensive material substitution maintains battery functionality while significantly reducing production costs across all components
Solution Approach 2:
The patent employs earth-abundant materials such as iron oxides and hydroxides that can be obtained from natural sources with minimal processing. These materials essentially serve themselves by being readily available in nature, reducing the need for complex extraction and refinement processes, thereby lowering production costs
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 use of graphite with a rhombohedral crystal structure in the aqueous battery improves reaction activity for hydroxide ion extraction and insertion, increasing charge-discharge efficiency and reducing production costs by utilizing an abundant resource, while maintaining battery functionality.
Implementation Method 1
uses insertion and extraction reactions of TFSI anions (N(SO2CF3)2−) between the graphite layers
Implementation Method 2
configured to use hydroxide ions (OH−) as carrier ions
Data Source
AI summary
Provided is an aqueous battery configured to use hydroxide ions (OH−) as carrier ions. The aqueous battery is an aqueous battery comprising a cathode layer, an anode layer and an aqueous liquid electrolyte, wherein the cathode layer contains, as a cathode active material, a graphite having a rhombohedral crystal structure; wherein the anode layer contains, as an anode active material, at least one selected from the group consisting of an elemental Zn, an elemental Cd, an elemental Fe, a Zn alloy, a Cd alloy, an Fe alloy, ZnO, Cd(OH)2, Fe(OH)2 and a hydrogen storage alloy; and wherein, as an electrolyte, at least one selected from the group consisting of KOH and NaOH is dissolved in the aqueous liquid electrolyte.