Lithium Nickel Composite Cathode for High-Capacity Battery Cycle Stability
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Solution Overview
Problem
High-capacity and large-area non-aqueous electrolyte secondary batteries using spinel type lithium manganese composite oxide as a positive electrode material face capacity deterioration due to non-uniform voltage across the electrode plane, leading to inadequate charge and discharge cycle characteristics.
Innovation Solution
The use of a composite oxide comprising lithium and nickel in combination with spinel type LiMn2O4 as a positive electrode active substance, with controlled average secondary particle diameters and content ratios within specific ranges, acts as an over-voltage promoter to suppress electrode deterioration and improve cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spinel type lithium manganese composite oxide is used as a positive electrode material to achieve high capacity, then the battery area to rated capacity ratio decreases, but capacity deterioration occurs due to non-uniform voltage across the electrode plane
Solution Approach 1:
The patent applies local quality by creating a composite positive electrode material where spinel type LiMn2O4 particles are coated with a lithium nickel-based composite oxide layer. This coating creates a gradient structure where the inner spinel core provides high capacity while the outer nickel-based layer provides over-voltage promotion at local sites, addressing the non-uniform voltage distribution problem in high-capacity batteries.
Solution Approach 2:
The patent uses composite materials by combining spinel type LiMn2O4 with lithium nickel-based composite oxide to form a core-shell structured positive electrode material. This composite structure allows the battery to achieve both high capacity (from the spinel core) and improved cycle characteristics (from the nickel-based coating that promotes uniform voltage distribution).
2Productivity
If the battery area to rated capacity ratio is reduced to increase capacity density, then more capacity can be packed in the same area, but electrode deterioration occurs due to non-uniform voltage distribution
Solution Approach 1:
The patent implements local quality by strategically coating spinel LiMn2O4 particles with lithium nickel-based composite oxide. The coating is not uniform across the entire electrode but is localized on the particle surfaces, creating local over-voltage promotion zones that prevent dendrite formation and voltage non-uniformity, enabling high capacity density without sacrificing electrode durability.
Solution Approach 2:
The patent applies parameter changes by controlling the particle size of spinel LiMn2O4 to 10 μm or less and adjusting the composition ratio of lithium nickel-based composite oxide (containing Ni, Co, Mn in specific proportions). These parameter optimizations enable high capacity density while maintaining electrode durability through improved voltage uniformity.
3Quantity of substance
If cobalt content is reduced to lower raw material cost, then resource scarcity and cost stability improve, but voltage and energy density may be affected
Solution Approach 1:
The patent applies parameter changes by formulating a lithium nickel-based composite oxide with specific composition parameters (Ni: 0.2-0.8, Co: 0.05-0.5, Mn: 0.05-0.5, satisfying Ni+Co+Mn=1.05-1.30). This compositional optimization allows the material to achieve both cost reduction (lower cobalt content) and maintained voltage/energy density through synergistic effects of the multi-element composite oxide.
Solution Approach 2:
The patent uses composite materials by creating a multi-element lithium nickel-based composite oxide containing Ni, Co, and Mn in optimized proportions. This composite approach replaces expensive cobalt-rich materials with a cost-effective multi-element composition that maintains high voltage and energy density through the synergistic contributions of each element.
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 configuration enhances the cycle characteristics of non-aqueous electrolyte secondary batteries by preventing electrode deterioration caused by non-uniform voltage, resulting in improved charge and discharge performance even at high capacity and large area.
Implementation Method 1
acts as an over-voltage promoter to suppress electrode deterioration and improve cycle characteristics
Data Source
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AI summary
[Object] Provided is a means for improving cycle characteristics by suppressing electrode deterioration resulting from non-uniformity of voltage across an electrode plane in a high-capacity and large-area non-aqueous electrolyte secondary battery that includes lithium nickel-based composite oxide as a positive electrode active substance. [Solving Means] Disclosed is a positive electrode for a non-aqueous electrolyte secondary battery used in a non-aqueous electrolyte secondary battery in which the ratio value of battery area (projected area of the battery including the battery outer casing body) to rated capacity is 5 cm2/Ah or more and the rated capacity is 3 Ah or more, the positive electrode comprising a positive electrode current collector and a positive electrode active substance layer that is formed on a surface of the positive electrode current collector and has a positive electrode active substance containing a lithium nickel-based composite oxide and a spinel type lithium manganese composite oxide, in which, when the average secondary particle diameter (D50) of the lithium nickel-based composite oxide is D50 (A) [µm], the content ratio of the lithium nickel-based composite oxide in the positive electrode active substance layer is A [% by mass], the average secondary particle diameter (D50) of the spinel type lithium manganese composite oxide is D50(B) [µm], and the content ratio of the spinel type lithium manganese composite oxide in the positive electrode active substance layer is B [% by mass], the positive electrode satisfies the following Mathematical Formula 1 and Mathematical Formula 2: 0<D50A/D50B≤15B/A+B≥0.05