Secondary Battery Outermost Electrode Inactive Material Layer
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Solution Overview
Problem
Lithium secondary batteries face performance deterioration due to abnormal electrochemical reactions at the outermost portion of the electrode assembly, leading to reduced reliability and safety concerns.
Innovation Solution
Incorporating an outermost electrode made of inactive materials, such as porous inorganic or organic materials, which do not cause electrochemical reactions, and positioning an inactive material layer on the current collector to prevent direct contact with the case, thereby enhancing the battery's safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode assembly uses only active materials throughout, then the energy density is maximized, but abnormal electrochemical reactions occur at the outermost portion leading to performance deterioration
Solution Approach 1:
The patent applies local quality by using inactive materials specifically at the outermost electrode portions where abnormal reactions occur, while maintaining active materials in the inner stacked electrodes for energy storage. This localized differentiation resolves the contradiction by protecting the vulnerable outer regions without sacrificing the energy-dense core structure.
Solution Approach 2:
The inactive material layer acts as an intermediary between the active electrode materials and the external environment (case). It prevents direct harmful interactions at the outermost portions while allowing the battery to maintain its functional active materials, thus mediating between energy density requirements and reliability concerns.
2Reliability
If the outermost electrode is made of inactive material, then abnormal electrochemical reactions are prevented, but the energy density of the battery is reduced
Solution Approach 1:
The patent minimizes the impact on energy density by limiting inactive materials to only the outermost electrode portions, while the majority of the electrode assembly (inner stacked electrodes) retains active materials for energy storage. This localized approach maintains safety while preserving overall energy density.
Solution Approach 2:
The electrode assembly becomes a composite structure combining active materials (for energy density) and inactive materials (for safety), arranged in specific configurations where inactive materials are positioned at outermost portions. This composite approach allows simultaneous optimization of both energy density and safety.
3Reliability
If the inactive material layer is positioned at the outermost portion, then direct contact between active material and case is prevented, but the device complexity increases
Solution Approach 1:
The patent merges the protective function with the electrode structure itself by making the outermost electrode portions consist of inactive materials, rather than adding a separate protective layer. This integration reduces overall device complexity while maintaining reliability benefits.
Solution Approach 2:
The outermost electrode portions serve multiple functions: they maintain the structural integrity of the electrode assembly while simultaneously acting as a protective barrier preventing direct contact between active materials and the case. This multi-functionality reduces the need for additional separate components.
Data Source
AI summary
Disclosed is a secondary battery which includes an electrode assembly comprising inner stacked electrodes and at least one outermost electrode positioned on at least one end of the inner stacked electrodes; and a case configured to house the electrode assembly. Herein, the at least one outermost electrode comprise an inactive material.