Metal Hydroxide in Battery Voids for Thermal Stability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries, such as lithium ion batteries, face issues with thermal stability due to heat generation during charging and discharging, which can lead to performance degradation and increased battery temperature, especially when internal short circuits occur. Existing techniques, like using compounds with heat absorption initiation temperatures between 200° C. to 400° C., do not sufficiently suppress temperature rises and can inhibit conduction paths, increasing resistance.
Innovation Solution
A positive electrode material is developed with metal hydroxides, like aluminum hydroxide, disposed inside the voids of the active material particles, which absorb heat through endothermic reactions, enhancing thermal stability while maintaining conduction paths and reducing resistance. The material includes lithium transition metal oxides with nickel, cobalt, and manganese, and is manufactured by mixing metal salts with active material particles, inducing a redox reaction to form hydroxides within the particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If compounds with heat absorption initiation temperature from 200°C to 400°C are added to the positive electrode active material layer, then thermal stability is improved, but the compound inhibits conduction paths and causes local resistance increase
Solution Approach 1:
The positive electrode active material layer is segmented into multiple particles, each containing voids with heat absorption compounds. This segmentation allows the conduction paths to form between particles while heat absorption compounds are isolated within individual particles, preventing resistance increase in conduction paths while maintaining thermal stability.
Solution Approach 2:
The voids within the positive electrode active material particles serve as intermediaries to accommodate heat absorption compounds. These voids act as isolated compartments that prevent the heat absorption compounds from interfering with the conduction paths between particles, thus resolving the contradiction between thermal stability and conductivity.
2Temperature
If heat absorption compounds are disposed close to the positive electrode active material, then temperature increase suppression is effective, but the arrangement complexity increases
Solution Approach 1:
The heat absorption compounds are nested within the voids of the positive electrode active material particles. This nested structure automatically positions the heat absorption compounds close to the active material without requiring complex external arrangements, thus achieving effective temperature suppression while simplifying the overall structure.
Solution Approach 2:
The positive electrode active material particles themselves provide the voids that accommodate the heat absorption compounds. This self-service approach eliminates the need for separate arrangement processes, as the particles inherently contain the necessary space for heat absorption compounds during their formation.
3Temperature
If metal hydroxide is disposed inside the voids of positive electrode active material particles, then thermal stability is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The manufacturing process utilizes parameter changes, specifically controlling the moisture content and temperature during formation, to enable metal hydroxides to precipitate within the voids. By adjusting these parameters, the precipitation process naturally fills the voids without requiring high precision positioning, thus achieving thermal stability enhancement while maintaining feasible manufacturing precision.
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
This configuration effectively suppresses temperature increases, maintains battery performance, and enhances thermal stability by utilizing the endothermic reaction of metal hydroxides, preventing high temperatures and reducing resistance in the battery.
Implementation Method 1
Metal hydroxides are known to absorb heat during thermal decomposition. Therefore, the positive electrode material disclosed herein can effectively suppress the increase in temperature of the positive electrode active material by the endothermic reaction of the metal hydroxide.
Data Source
AI summary
Provided is a positive electrode material for a nonaqueous electrolyte secondary battery that excels in thermal stability. A positive electrode material for a nonaqueous electrolyte secondary battery, which is provided by the present invention, includes positive electrode active material particles that can reversibly store and release a charge carrier, and a metal hydroxide. Each of the positive electrode active material particles has inside thereof a void and the metal hydroxide is disposed inside the void.