Composite Cathode Material for Lithium Battery Structural Stability
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Solution Overview
Problem
Lithium nickel oxide batteries with high nickel content have improved capacity and power output but lack structural stability during charging and discharging due to high residual lithium content, leading to reduced lifespan and performance.
Innovation Solution
A composite positive active material is developed, comprising a first metal oxide with a layered structure and a second metal oxide with a perovskite, rock salt, or spinel structure, where the second metal oxide is introduced as a secondary phase to reduce residual lithium and enhance structural stability, manufactured through a method involving mixing precursors and thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high nickel content is used in lithium nickel oxide, then capacity and power output are improved, but structural stability deteriorates due to high residual lithium content
Solution Approach 1:
The patent applies composite materials by combining lithium nickel oxide with a secondary phase material (lithium manganese oxide, lithium iron phosphate, or their composites) to create a composite positive active material. This composite structure allows the material to maintain high nickel content for improved capacity and power output while the secondary phase provides structural stability and reduces residual lithium content, thus resolving the contradiction between productivity and stability.
2Productivity
If high nickel content is used in lithium nickel oxide, then capacity and power output are improved, but lifespan is reduced due to structural instability
Solution Approach 1:
The composite structure with secondary phase material stabilizes the crystal structure during repeated charging and discharging cycles, preventing structural degradation and extending the battery lifespan while maintaining high nickel content for high capacity and power output.
3Stability of the object's composition
If residual lithium content is reduced to improve structural stability, then structural stability and lifespan are improved, but capacity and power output may be affected
Solution Approach 1:
The patent applies local quality by introducing secondary phase material at specific locations (as a coating or dispersed phase) within the positive active material structure. This localized addition reduces residual lithium content and improves structural stability without significantly affecting the overall high nickel content and electrochemical performance, thus resolving the contradiction between stability and productivity.
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 composite active material reduces residual lithium to 15,000 ppm or less, improving the structural stability and lifespan of lithium batteries while maintaining high power output and capacity, with reduced voltage decay even after repeated charging and discharging cycles.
Implementation Method 1
thermally treating the composition for forming the composite positive active material to prepare the composite positive active material
Data Source
AI summary
A composite positive active material includes: a composite including a first metal oxide represented by Formula 1 and having a layered structure, and a second metal oxide having at least one crystal structure selected from a layer structure, a perovskite structure, a rock salt structure, and a spinel structure, wherein a content of the second metal oxide is greater than 0 and equal to or less than 0.2 moles, per mole of the composite,LiNixM11-xO2-eM2e Formula 1wherein, in Formula 1, M1 is at least one element selected from Group 4 to Group 14 of the Periodic Table of the Elements; Ma is at least one element selected from F, S, Cl, and Br; 0.7≤x<1; and 0≤e<1. Also, a positive electrode including the composite positive active material, and a lithium battery including the positive electrode.