Positive Electrode Composition With Sulfamic Acid for Thermal Short Safety
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Solution Overview
Problem
Existing positive electrode materials for secondary batteries, such as those described in Patent Literature 1, face challenges in balancing electrical conductivity with thermal stability, leading to increased resistance and reduced battery performance, especially when internal short circuits occur.
Innovation Solution
A positive electrode for a secondary battery comprising a current collector and an active material layer containing active material particles, a binder, and a thermal decomposable additive like sulfamic acid, which is selectively distributed to increase internal resistance only at high temperatures, thereby enhancing safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical conductivity of the powder compact is controlled to improve thermal stability, then the thermal stability in charged state is improved and Joule heat generation is suppressed, but the battery ends up with high resistance causing deterioration in battery performance
Solution Approach 1:
The invention changes the temperature-dependent electrical resistance parameter by introducing a thermal decomposable additive (sulfamic acid) that remains conductive at room temperature but transforms at high temperatures. This allows the battery to maintain low resistance for good performance under normal conditions while achieving high resistance for safety under thermal runaway conditions.
Solution Approach 2:
The invention makes the electrical resistance dynamic rather than static by using a thermal decomposable additive that changes its electrical properties with temperature. The additive provides low resistance at operating temperatures but transforms at high temperatures to provide high resistance, creating a dynamically adaptive safety mechanism.
2Use of energy by moving object
If existing positive electrode materials are used to achieve high energy density, then energy density is increased, but Joule heat generation during internal short circuit increases and safety deteriorates
Solution Approach 1:
The invention converts the harmful effect of high conductivity (which causes excessive Joule heat during short circuit) into a beneficial safety feature. By using a thermal decomposable additive that transforms at high temperatures, the high conductivity that normally enables good battery performance becomes a trigger for increased resistance that suppresses Joule heat generation during thermal runaway, turning a performance advantage into a safety mechanism.
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 proposed solution effectively suppresses Joule heat generation during internal short circuits by selectively increasing battery internal resistance at high temperatures, thus ensuring high safety and maintaining good battery performance.
Implementation Method 1
the positive electrode active material layer contains active material particles, a binder, and a thermal decomposable additive, the thermal decomposable additive includes a sulfamic acid
Data Source
AI summary
A positive electrode for a secondary battery including a positive electrode current collector, and a positive electrode active material layer supported on the positive electrode current collector. The positive electrode active material layer contains active material particles, a binder, and a thermal decomposable additive. The thermal decomposable additive includes a sulfamic acid. The binder includes at least one selected from the group consisting of a fluorocarbon resin and a hydrogenated nitrile butadiene rubber.