Lithium-Rich Cathode Material Optimizing Load Characteristics
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Solution Overview
Problem
Current secondary batteries face challenges in improving load characteristics, particularly due to increased resistance and lowered cycle characteristics when using lithium-rich lithium-containing compounds, which limits their practical application in high-capacity and high-voltage scenarios.
Innovation Solution
A lithium-rich lithium-containing compound with a bedded salt-type crystal structure is used, characterized by a specific surface area and crystallite diameter product of at least 1.4×10−6 cubic meters per gram, optimizing the balance between surface area and crystallite size to reduce grain boundary and electrode interface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lithium-rich lithium-containing compound is used to improve cycle characteristics, then cycle characteristics are improved, but load characteristics are lowered due to increased resistance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the product of specific surface area and crystallite diameter (SD ≥ 1.4×10^-6 m³/g) of the lithium-rich lithium-containing compound. This parameter optimization resolves the contradiction by finding the optimal balance point where cycle characteristics are maintained while load characteristics are improved through reduced resistance.
Solution Approach 2:
The patent uses a composite material approach by combining the lithium-rich lithium-containing compound with a specific crystal structure (bedded salt-type) and controlled morphological parameters. This composite structure achieves both improved cycle characteristics and load characteristics by integrating multiple material properties.
2Quantity of substance
If charging voltage is increased to achieve high battery capacity, then battery capacity is improved, but cathode active material is easily degraded and cycle characteristics are lowered
Solution Approach 1:
The patent changes the physical parameters of the cathode active material by controlling the product of specific surface area and crystallite diameter (SD ≥ 1.4×10^-6 m³/g). This parameter optimization allows the material to withstand higher charging voltages without degradation, thereby achieving both high battery capacity and maintained cycle characteristics.
3Productivity
If specific surface area is increased to improve lithium ion insertion/extraction, then load characteristics are improved, but grain boundary and electrode interface resistance increase
Solution Approach 1:
The patent applies parameter changes by optimizing not just the specific surface area alone, but rather the product of specific surface area and crystallite diameter (SD ≥ 1.4×10^-6 m³/g). This combined parameter control resolves the contradiction by ensuring that increased surface area does not come at the cost of excessive grain boundary resistance, as the crystallite diameter factor balances the structural integrity.
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
This approach enhances the load characteristics of secondary batteries, allowing for easier insertion and extraction of lithium ions even at high voltages, thereby improving battery performance and stability.
Implementation Method 1
lithium ions are less likely to be inserted and extracted mainly due to increased resistance
Data Source
AI summary
A cathode active material is a lithium-rich lithium-containing compound having a bedded salt-type crystal structure. A product SD of a specific surface area S in square meters per gram and a crystallite diameter D in micrometer is equal to or more than about 1.4×10−6 cubic meters per gram.