Porous LiNiCoAlO2 Cathode Material for High-Capacity Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current positive electrode active materials for lithium secondary batteries, such as LiNi1/3Co1/3Mn1/3O2, have limited capacity and electrochemical properties, making them unsuitable for high-capacity applications like electric vehicle batteries.
Innovation Solution
A method to prepare a porous positive electrode active material with a specific structure (Li1+zNi1−x−yCoxAlyO2) by mixing nickel, cobalt, and aluminum sources with ammonia water and sucrose, followed by lithium addition and heat-treatment, resulting in a material with high specific surface area, pore volume, and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional positive electrode active materials (e.g., LiNi1/3Co1/3Mn1/3O2) are used, then the battery structure is simple and manufacturing is easy, but the capacity is limited to about 150 mAh/g and electrochemical properties are insufficient
Solution Approach 1:
The patent applies porous materials by constructing a hierarchical porous structure on the positive electrode active material surface through controlled precipitation processes. This porous structure increases the specific surface area and provides pathways for lithium ion diffusion, thereby significantly enhancing capacity from 150 mAh/g to over 200 mAh/g while maintaining structural integrity
Solution Approach 2:
The patent employs composite materials by combining multiple metal elements (Ni, Co, Mn, Al) in specific ratios within the spinel structure Li1-xMnxAl0.5-xNi0.5O2. This composite approach leverages the advantages of each element: Ni for high capacity, Co for stability, Mn for structural framework, and Al for surface protection, achieving both high capacity and good electrochemical properties
2Quantity of substance
If the capacity of positive electrode active material is increased to exceed 200 mAh/g, then high-rate capability and electrochemical properties are improved, but the manufacturing process becomes more complex requiring multiple steps including precipitation, drying, and firing
Solution Approach 1:
The patent applies preliminary action by pre-forming the porous structure and optimizing the metal element distribution during the precipitation stage before drying and firing. The controlled precipitation process creates a hierarchical porous structure in advance, and the subsequent drying and firing steps only need to remove water and crystallize the structure, significantly simplifying the overall manufacturing process while achieving high capacity
Solution Approach 2:
The patent employs parameter changes by optimizing the pH value (8-10), temperature (20-40°C), and metal element ratios during precipitation to control the formation of porous structure and element distribution. By adjusting these parameters, the process achieves high capacity materials with improved manufacturability through standardized control conditions
3Speed
If a hierarchical porous structure is constructed on the positive electrode active material, then lithium ion diffusion rate increases and electrochemical properties are enhanced, but the specific surface area control becomes more difficult requiring precise pH and temperature control
Solution Approach 1:
The patent applies feedback by monitoring and controlling pH value and temperature during the precipitation process to maintain optimal conditions for hierarchical porous structure formation. The pH is controlled within 8-10 and temperature within 20-40°C, with adjustments made based on observed precipitation behavior, ensuring consistent specific surface area and lithium ion diffusion properties
Solution Approach 2:
The patent employs parameter changes by systematically optimizing pH (8-10), temperature (20-40°C), and metal element ratios to control the precipitation kinetics and porous structure formation. These parameter adjustments enable precise control of specific surface area while maintaining high lithium ion diffusion rates through the hierarchical porous architecture
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 prepared material exhibits improved high-rate capability and capacity, with capacities exceeding 200 mAh/g, and enhanced lithium ion diffusion rates, leading to better electrochemical properties.
Implementation Method 1
Lithium ions in the electrolyte move to the negative electrode at the time of charging and move to the positive electrode at the time of discharging
Implementation Method 2
excess electrons are discharged or absorbed in each electrode, thereby causing a chemical reaction. The electron flows in the electric wire in this process, and as a result, electric energy is generated
Implementation Method 3
adding a lithium source to the positive electrode active material precursor and firing them to prepare a positive electrode active material
Data Source
AI summary
Provided is a method for preparing a positive electrode active material for a lithium secondary battery, the method comprising: mixing and reacting a nickel source, a cobalt source, and an aluminum source, ammonia water, sucrose, and a pH adjusting agent to prepare a mixed solution; drying and oxidizing the mixed solution to prepare a positive electrode active material precursor; and adding a lithium source to the positive electrode active material precursor and firing them to prepare a positive electrode active material for a lithium secondary battery.