Lithium Nickel Complex Oxide Cathode Material Manufacturing
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Solution Overview
Problem
Lithium secondary batteries face limitations in high-temperature stability, cost, and capacity due to the use of lithium cobalt oxides, while lithium nickel oxides suffer from rapid phase transitions and instability in air and humidity, necessitating improved cathode active materials for electric vehicle applications.
Innovation Solution
A method of manufacturing lithium nickel complex oxide by adjusting the ratio of divalent nickel (NiII) to trivalent nickel (NiIII) using a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer, which involves mixing lithium nickel oxide with the copolymer and heat treating the mixture to increase the NiII ratio, thereby enhancing capacity characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium cobalt oxides are used as cathode active materials, then charge and discharge efficiency and life characteristics are improved, but cost increases and high-temperature stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by replacing cobalt with nickel to form lithium nickel oxides and their composite materials, thereby reducing cost while maintaining electrochemical performance
Solution Approach 2:
The patent uses composite materials combining lithium nickel oxide with other materials to achieve both cost reduction and maintained stability, avoiding the need for expensive cobalt
2Ease of manufacture
If lithium nickel oxides are used as cathode active materials, then cost decreases and discharge capacity increases, but phase transition occurs and stability in air and humidity deteriorates
Solution Approach 1:
The patent applies a coating layer on the lithium nickel oxide surface that acts as a protective shell, preventing direct contact with air and humidity while maintaining the core material's high capacity and low cost properties
Solution Approach 2:
The patent creates composite structures where lithium nickel oxide is combined with stable materials that protect against phase transition and environmental degradation
3Quantity of substance
If lithium nickel oxides are used as cathode active materials, then discharge capacity increases, but phase transition of crystal structure occurs due to volume changes
Solution Approach 1:
The patent optimizes the chemical composition parameters of lithium nickel oxide to achieve a balance between high discharge capacity and crystal structure stability, preventing phase transitions during cycling
Solution Approach 2:
The patent uses composite materials that accommodate volume changes during charge-discharge cycles, maintaining crystal structure stability while preserving high discharge capacity
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 method improves the electrochemical performance of secondary batteries by increasing the NiII ratio, leading to enhanced charge stability, cycle stability, and capacity, making them more suitable for high-voltage applications in electric vehicles.
Implementation Method 1
heat treating the mixture to increase the NiII ratio
Data Source
AI summary
Provided is a lithium nickel complex oxide represented by Chemical Formula 1:LiwNiIIx1NiIIIx2MnyCozFdO2-d <Chemical Formula 1>where x1+x2+y+z=1,0.4≤x1+x2≤0.9,0<y≤0.6 and 0<z≤0.6,0.9≤w≤1.3, and 0<d≤0.3.