Positive Electrode Structure for Non-Aqueous Battery
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Solution Overview
Problem
Nonaqueous electrolyte batteries face issues with capacity degradation and resistance increase during charge-discharge cycles due to the orientation and dispersion of active materials in the positive electrode, leading to inefficient energy storage and stability concerns.
Innovation Solution
A positive electrode with a specific composition and structure, including a first active material represented by Li x Ni 1-a-b Co a M b O 2 and a second active material as Li a CoM h O 2, where M is selected from certain elements, optimized for pore distribution and particle size, combined with an electron conductive substance and binder, to achieve a balanced distribution of primary and secondary particles, reducing resistance and capacity loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the active material is dispersed in suspension and applied to current collector, then the electrode can be formed, but the orientation of active material varies leading to capacity degradation and resistance increase
Solution Approach 1:
The patent changes the physical state parameter of active material from suspended particles to pre-formed granules with controlled pore structure. This parameter change eliminates orientation issues during coating while maintaining electrochemical performance, resolving the contradiction between manufacturing precision and reliability
Solution Approach 2:
The patent uses composite granules containing active material particles aggregated with pore structure, combining the benefits of high surface area with controlled morphology. This composite structure prevents orientation variability while maintaining electrochemical activity, addressing both manufacturing precision and battery reliability
2Ease of manufacture
If the positive electrode material layer is formed by conventional coating and pressing, then the electrode structure is created, but pore distribution is not optimized leading to resistance increase
Solution Approach 1:
The patent performs preliminary formation of granules with optimized pore distribution before electrode assembly. This preliminary action ensures that the desired pore structure and resistance characteristics are established prior to coating, maintaining ease of manufacture while improving reliability
Solution Approach 2:
The patent employs porous granular active material with controlled pore volume and distribution. The porous structure facilitates electrolyte penetration and ion transport, reducing resistance while maintaining simple coating and pressing processes for electrode fabrication
3Productivity
If the active material particles are aggregated to form secondary particles, then the electrode density increases, but capacity degradation occurs during charge-discharge cycles
Solution Approach 1:
The patent applies local quality by creating granules with heterogeneous internal structure - dense regions for high density and controlled pore regions for electrolyte access. This local differentiation maintains productivity through high density while preserving reliability via adequate ion transport pathways
Solution Approach 2:
The patent incorporates controlled porosity within aggregated granules, creating internal channels for electrolyte penetration. This porous structure within aggregates maintains high energy density while preventing capacity degradation by ensuring uniform lithium ion distribution during charge-discharge cycles
Data Source
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AI summary
According to one embodiment, a positive electrode includes a positive electrode material layer and a positive electrode current collector on which the positive electrode material layer is formed. The positive electrode material layer includes a positive electrode active material having a composition represented by a formula (1) described below. The positive electrode material layer satisfies a formula (2) described below. LixNi1-a-bCoaMbO2 (1) 35≤S1/V1≤70