Secondary Battery Positive Electrode Intermediate Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in preventing temperature rise due to internal shorts, as thermally sensitive resistors like BaTiO3 may reduce battery performance and fail to maintain high resistance after temperature drop, leading to continued heat generation.
Innovation Solution
A positive electrode design featuring an intermediate layer with an electrically conductive inorganic compound that reacts to become an insulating oxide at 300°C or more, sandwiched between the current collector and the active material layer, which acts as a high-resistant component to restrain short circuit current and prevent temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BaTiO3 is used as a thermally sensitive resistor in the positive electrode, then short circuit current can be restrained when the battery generates heat due to internal short, but the battery performance is largely reduced because BaTiO3 has higher resistivity at room temperature than carbon
Solution Approach 1:
The patent changes the electrical conductivity parameter of the intermediate layer dynamically. At normal operating temperatures, the layer maintains high conductivity (using carbon or conductive metal particles) to ensure good battery performance. When temperature reaches 300°C or higher due to internal short, the conductive particles transform to insulating oxide, dramatically increasing resistance to restrain short circuit current.
Solution Approach 2:
The intermediate layer uses composite materials combining conductive particles (carbon or conductive metal particles) with insulating inorganic material. This composite structure allows the layer to exhibit dual characteristics: high conductivity at normal temperatures for good performance, and high resistance at elevated temperatures for safety, resolving the contradiction between performance and safety.
2Object-affected harmful factors
If a layer including a thermally sensitive resistor is used to restrain short circuit current, then heat generation can be limited temporarily, but the resistance decreases again when battery temperature falls down, causing heat generation to continue and temperature rise to persist
Solution Approach 1:
The patent employs accelerated oxidation of conductive metal particles at high temperatures to transform them into insulating oxide. This chemical transformation is triggered by the high temperature condition (300°C or higher) and permanently changes the electrical properties of the particles, ensuring that resistance remains high even after temperature fluctuations, thus preventing continued heat generation.
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 prevents temperature rise after internal shorts by maintaining high resistance even as the battery cools, ensuring the battery's safety and performance by securing electrical conduction in normal conditions and restricting heat generation.
Implementation Method 1
the electrically conductive inorganic compound reacts to become an insulating oxide at 300° C. or more
Implementation Method 2
acts as a high-resistant component to restrain short circuit current and prevent temperature rise
Data Source
AI summary
This secondary battery positive electrode is provided with a positive-electrode current collector, a positive-electrode mixture layer, and an intermediate layer disposed between the positive-electrode current collector and the positive-electrode mixture layer. The intermediate layer comprises: a first intermediate layer that includes a non-oxide conductive inorganic compound and a positive-electrode active material; and a second intermediate layer that includes an insulating inorganic material and a non-oxide conductive inorganic compound. The conductive inorganic compound becomes an insulating oxide at 300° C. or above.