Alkaline Battery Cathode Composition for High Energy Density Shelf Life
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Solution Overview
Problem
Alkaline batteries face challenges in achieving high volumetric energy density and ambient shelf life due to limitations in cathode active materials, particularly in preventing direct reactions between the negative and positive electrodes and maintaining electrical charge balance during discharge.
Innovation Solution
The development of non-stoichiometric alkali metal oxides synthesized through acid treatment of stoichiometric alkali metal oxides, which increases the oxidation state of transition metals, reduces alkali metal content, and incorporates protons to stabilize the crystal structure, resulting in a cathode active material with high energy density and low solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If stoichiometric alkali metal oxide is used in the cathode, then the battery can maintain electrical charge balance during discharge, but the volumetric energy density is limited
Solution Approach 1:
The patent applies parameter changes by modifying the stoichiometric composition of the alkali metal oxide to create a non-stoichiometric compound with formula A1-xHyMa1-x-tMbxMctO2. This changes the oxidation state of transition metals and reduces alkali metal content, thereby increasing volumetric energy density while maintaining structural stability through proton incorporation
Solution Approach 2:
The patent uses composite materials by creating a multi-element oxide system combining alkali metal (A), transition metals (Ma, Mb), dopant (Mc), and proton (H). This composite structure allows simultaneous optimization of energy density through variable composition and stability through the stabilizing effect of protons and dopants on the crystal lattice
2Use of energy by moving object
If acid treatment is applied to increase oxidation state and reduce alkali metal content, then volumetric energy density improves, but crystal structure stability may be compromised
Solution Approach 1:
The patent uses protons (H+) as intermediaries that partially substitute for alkali metal ions in the crystal structure. These protons act as mediators that maintain crystal structure stability during acid treatment by filling vacancies and stabilizing the lattice, while still allowing reduction of alkali metal content to increase energy density
Solution Approach 2:
The patent controls the degree of acid treatment by adjusting parameters such as acid concentration, treatment time, and temperature to achieve optimal proton substitution level (x value in A1-xHy). This controlled parameter change ensures sufficient alkali metal removal for high energy density while maintaining enough structural integrity for stability
3Productivity
If higher oxidation state of transition metal is achieved, then battery capacity increases, but solubility and shelf life may be affected
Solution Approach 1:
Protons serve as stabilizing intermediaries in the crystal structure that prevent excessive solubility of high oxidation state transition metals. The protons balance the charge and stabilize the lattice, preventing decomposition reactions that would otherwise occur with high oxidation state metals, thereby extending shelf life while maintaining high capacity
4Use of energy by moving object
If non-stoichiometric composition is used to increase energy density, then volumetric energy density improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent simplifies manufacturing by changing the synthesis approach from precise stoichiometric mixing to a more robust acid treatment process. The non-stoichiometric composition is achieved through controlled acid leaching rather than precise initial mixing, reducing the need for ultra-precise weighing and mixing equipment while maintaining composition control through process parameters
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 acid-treated non-stoichiometric metal oxides in alkaline batteries enhances their volumetric energy density, thermal stability, and ambient shelf life by maintaining structural integrity and preventing undesirable side reactions, leading to improved discharge performance and extended storage capabilities.
Implementation Method 1
The non-stoichiometric alkali metal oxide can be synthesized by acid treatment of a stoichiometric alkali metal oxide to remove alkali metal and to increase the oxidation state of the metal
Implementation Method 2
an aqueous acid can provide protons which can partially displace alkali metal ions within the metal oxide crystal structure and help maintain the stability of the crystal structure
Implementation Method 3
incorporates protons to stabilize the crystal structure
Data Source
AI summary
A primary battery includes a cathode having a non-stoichiometric metal oxide including transition metals Ni, Mn, Co, or a combination of metal atoms, an alkali metal, and hydrogen; an anode; a separator between the cathode and the anode; and an alkaline electrolyte.