Acidic Oxide Additive Suppresses Slurry Gelation in Lithium-Ion Cathodes
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Solution Overview
Problem
Lithium ion secondary batteries face challenges with high costs due to scarce cobalt resources and instability of crystal structures, leading to poor output power characteristics and gelation issues in the positive electrode slurry, which affects yield and operability.
Innovation Solution
A positive electrode composition is developed using a lithium transition metal complex oxide with specific composition and acidic oxide particles, which suppresses gelation and enhances output power characteristics by reacting with lithium hydroxide and acting as a conductive agent, thereby improving the battery's performance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiNi0.5Co0.2Mn0.3O2 is used to reduce costs and improve discharge capacity, then cost and discharge capacity are improved, but output power characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by adjusting the lithium content to Li1+x (excess lithium) and modifying the transition metal composition ratios to optimize both discharge capacity and output power characteristics. This resolves the contradiction by tuning the chemical parameters of the cathode material to achieve high capacity while maintaining good power performance.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (Ni, Co, Mn) in specific ratios within the Li1+xNiyCozMn1-y-zO2 structure. This composite approach allows the material to exhibit both high discharge capacity from nickel and good output power characteristics from the synergistic effects of cobalt and manganese, resolving the trade-off between capacity and power.
2Power
If excess lithium is added to improve output power characteristics, then output power characteristics are improved, but gelation of positive electrode slurry occurs
Solution Approach 1:
The patent introduces an intermediary substance (slurry stabilizer or coating layer) that mediates between the excess lithium in the cathode material and the binder in the slurry. This intermediary prevents direct harmful interactions that cause gelation, allowing the benefits of excess lithium for power characteristics to be realized without the detrimental gelation effect.
Solution Approach 2:
The patent employs a disposable protective coating or stabilizer layer on the cathode particles that prevents gelation during slurry preparation. This short-living protective element is consumed or removed during processing, allowing the underlying high-lithium cathode material to function without causing slurry gelation.
3Power
If LiCoO2 is used as positive electrode active material, then discharge capacity and power characteristics are maintained, but cost increases due to scarce cobalt
Solution Approach 1:
The patent applies parameter changes by systematically varying the transition metal composition ratios (Ni:Co:Mn) in the Li1+xNiyCozMn1-y-zO2 structure to find the optimal balance point. By adjusting these parameters, the patent achieves cost reduction through lower cobalt content while maintaining acceptable power characteristics, resolving the cost-performance contradiction.
Solution Approach 2:
The patent applies local quality by concentrating cobalt in specific regions or layers of the cathode structure rather than uniformly distributing it throughout. This allows reduced overall cobalt content (lowering cost) while maintaining local high-performance regions that provide necessary power characteristics.
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 gelation of the positive electrode slurry, increases production yield, and enhances output power characteristics of lithium ion secondary batteries, making them suitable for mobile devices and electric vehicle applications while reducing costs.
Implementation Method 1
reacting with lithium hydroxide
Implementation Method 2
acting as a conductive agent
Data Source
Figure 1~2
Figure 3~4
AI summary
A positive electrode composition that has improved output power characteristics and low costs, and is also easily handled upon production of a positive electrode, and exhibits an improved yield is provided. A positive electrode composition comprising a positive electrode active material composed of a lithium transition metal complex oxide represented by the general formula Li 1+x Ni y Co z M 1-y-z-w L w O 2 (wherein 0 ‰¤ x ‰¤ 0.50, 0.30 ‰¤ y ‰¤ 1.0, 0 < z ‰¤ 0.5, 0 ‰¤ w ‰¤ 0.1, 0.30 < y + z + w ‰¤ 1, M represents at least one kind selected from Mn and Al, and L represents at least one kind of an element selected from the group consisting of Zr, Ti, Mg and W), and additive particles composed of acidic oxide particles is used for positive electrode.