Nonaqueous Battery Cathode Composition for High-Voltage Gas Suppression
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries with lithium composite oxides of different particle sizes generate excessive gas when stored at high temperatures after being charged to high voltages, leading to potential battery degradation.
Innovation Solution
Incorporating lithium composite oxide particles A and B with specific particle size distributions and additives like zirconium or boron into the positive electrode, where particles A include secondary aggregations of smaller primary particles and particles B consist of larger primary and smaller secondary particles, to stabilize the crystal structure and reduce metal elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge voltage is increased to improve energy density, then the energy density increases, but the amount of gas generated during high-temperature storage increases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core particles have different composition and properties than the outer shell particles. The core contains lithium composite oxide with specific particle size and composition, while the shell contains different lithium composite oxide particles that form a protective layer. This local differentiation allows the battery to achieve high energy density through optimized core particles while the shell particles suppress gas generation during high-temperature storage.
Solution Approach 2:
The patent uses composite materials by combining two types of lithium composite oxide particles with distinct characteristics into a single positive electrode material system. The core particles provide high capacity for energy density, while the shell particles provide stability to suppress gas generation. This composite approach allows simultaneous optimization of both energy density and thermal stability without requiring a single material to satisfy conflicting requirements.
2Reliability
If lithium composite oxides of different particle sizes are used to improve battery characteristics, then the battery performance improves, but gas generation occurs during high-temperature storage after charging to high voltage
Solution Approach 1:
The patent applies segmentation by dividing the positive electrode active material into two distinct particle size segments: core particles with smaller particle size (D50: 3-6 μm) and shell particles with larger particle size (D50: 6-12 μm). This segmentation allows each particle size range to fulfill specific functions - the smaller core particles provide high surface area for electrochemical reactions while the larger shell particles provide structural stability, together suppressing gas generation during high-temperature storage.
Solution Approach 2:
The patent implements local quality by assigning different particle size characteristics to different spatial regions of the electrode structure. The core region contains smaller particles optimized for electrochemical activity, while the outer region contains larger particles optimized for structural stability. This spatial differentiation of particle sizes allows the battery to maintain good charge-discharge characteristics while suppressing gas generation during storage.
3Use of energy by moving object
If high voltage charging is applied to increase energy density, then the energy storage capacity increases, but metal elution and crystal structure instability occur during high-temperature storage
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable shell structure around the core particles before the battery undergoes high-temperature storage. The shell particles are deliberately designed with larger particle size and specific composition to create a protective barrier that prevents metal elution and stabilizes the crystal structure in advance. This preliminary protective structure is established during electrode fabrication, so when high-temperature storage occurs after high-voltage charging, the damage is already prevented.
Solution Approach 2:
The patent uses composite materials to create a core-shell structure where the shell material acts as a protective layer against crystal structure degradation and metal elution. The composite structure combines the high capacity characteristics of the core lithium composite oxide with the high stability characteristics of the shell lithium composite oxide, allowing the battery to withstand high-temperature storage conditions while maintaining energy storage capacity gained from high-voltage charging.
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes lithium composite oxide particles A and B containing Ni and Mn. The lithium composite oxide particles A include secondary particles a2 that are aggregations of primary particles a1, and contain at least one of zirconium and boron. The lithium composite oxide particles B include at least one of primary particles b1 and secondary particles b2, the primary particles b1 having a larger particle size than the primary particles a1, the secondary particles b2 being aggregations of the primary particles b1 and having a smaller particle size than the secondary particles a2. The mass ratio of the lithium composite oxide particles A to the lithium composite oxide particles B is within the range of 8:2 to 4:6.