Positive Electrode Material for Lithium Battery Short-Circuit Resistance
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high power density and durability, particularly in preventing excessive temperature increases during internal short-circuiting events, such as when a conductive foreign object is inserted, which can lead to reduced internal short-circuit resistance.
Innovation Solution
A positive electrode material is developed comprising a lithium transition metal composite oxide, a barium titanate-based dielectric, and specific compounds (Ba and Ti-containing oxides) that form a hetero-interface, enhancing electrical resistance temperature dependence and dielectric polarization, thereby improving output characteristics and internal short-circuit resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a barium titanate-based dielectric is adhered to the surface of a positive electrode active material, then output characteristics are improved, but battery temperature increases greatly during internal short-circuiting
Solution Approach 1:
The patent creates a composite structure by adhering a barium titanate-based dielectric to the surface of a positive electrode active material. This composite material combines the high power density benefits of the dielectric with the thermal management properties of the active material, resolving the contradiction between improved output characteristics and excessive temperature increase during internal short-circuiting
Solution Approach 2:
The dielectric is applied locally to the surface of the positive electrode active material rather than uniformly throughout the entire electrode. This localized application allows the surface to benefit from enhanced dielectric properties for improved output characteristics, while the bulk material maintains its thermal management capabilities during internal short-circuiting events
2Power
If the dielectric content is increased to improve output characteristics, then power density is enhanced, but internal short-circuit resistance decreases
Solution Approach 1:
The patent optimizes the dielectric content parameter to a specific range (0.1-10 mol%) rather than simply maximizing it. This parameter optimization achieves the right balance where sufficient dielectric content provides enhanced power density through improved polarization, while maintaining adequate internal short-circuit resistance for safety
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 solution effectively reduces battery temperature increases during internal short-circuiting and maintains excellent output characteristics even after high-rate charging and discharging cycles, demonstrating enhanced internal short-circuit resistance and power density.
Implementation Method 1
in a part with which the dielectric and at least one of Compounds I and II are in contact, a specific hetero-interface is formed, and lattice distortion occurs in the crystal structure
Implementation Method 2
the electrical resistance at the hetero-interface has temperature dependence. That is, at the hetero-interface, the electrical resistance is reduced to a low level when the battery is in a general usage temperature range, but the battery resistance rapidly increases if the temperature exceeds the general usage temperature range
Implementation Method 3
in the positive electrode material, dielectric polarization increases at the hetero-interface, and lithium ions are attracted to the positive electrode active material more favorably
Data Source
AI summary
A positive electrode material for a lithium secondary battery of the present disclosure includes a positive electrode active material, a barium titanate-based dielectric, and at least one of Compound I which contains the element Ba and has the largest peak at a position with 2θ=24° to 26° in an X-ray diffraction pattern obtained according to X-ray diffraction measurement using CuKα rays; and Compound II which contains the element Ti and has the largest peak at a position with 2θ=26° to 28° in an X-ray diffraction pattern obtained according to X-ray diffraction measurement using CuKα rays. At least one of Compounds I and II is disposed in contact with the dielectric.