Nickel-Rich Cathode Preparation Using Dehydrated Lithium Salt
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Solution Overview
Problem
Rechargeable lithium batteries face limitations in achieving high capacity and cost-effectiveness due to the use of lithium-containing cobalt oxide, which has limited resource availability and high costs, while lithium manganese oxides offer environmental benefits but suffer from low capacity and cycle characteristics.
Innovation Solution
A method for preparing a nickel-based lithium transition metal oxide by mixing nickel, cobalt, and optional metal compounds, undergoing co-precipitation, primary and secondary heat treatments, and incorporating a dehydrated lithium salt to optimize the composition and structure for improved capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-containing cobalt oxide (LiCoO2) is used as positive active material, then charge and discharge efficiency and cycle-life characteristics are improved, but capacity is reduced and cost increases due to cobalt resource limitation
Solution Approach 1:
The patent uses composite materials by combining nickel oxide (LiNiO2) and cobalt oxide (LiCoO2) in a specific ratio (0.95≤x<1 and 0<x≤0.05) to create a positive active material that leverages the high capacity of nickel-based compounds while incorporating cobalt to maintain cycle-life characteristics and charge/discharge efficiency. This composite approach resolves the contradiction by achieving both high capacity and reliable cycle performance.
2Reliability
If lithium-containing cobalt oxide (LiCoO2) is used as positive active material, then charge and discharge efficiency and cycle-life characteristics are improved, but cost increases due to cobalt resource limitation
Solution Approach 1:
The patent creates a cost-effective composite material by using a nickel-rich composition (0.95≤x<1) with a small amount of cobalt (0<x≤0.05). This reduces cobalt content and associated costs while maintaining the cycle-life characteristics and charge/discharge efficiency that cobalt provides. The composite structure allows cost reduction without sacrificing reliability.
3Object-affected harmful factors
If lithium manganese oxide (LiMn2O4) is used as positive active material, then environmental friendliness is improved, but capacity and cycle characteristics are reduced
Solution Approach 1:
The patent develops a nickel-based composite positive active material (LiNi1-xCoxO2) that combines the environmental benefits of reduced cobalt content with enhanced capacity compared to lithium manganese oxide. By optimizing the nickel-cobalt ratio, the invention achieves high capacity (0.3≤x<1) while maintaining environmental friendliness through lower toxic metal content and improved cycle characteristics compared to manganese-based materials.
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 enhances the capacity and cycle-life characteristics of rechargeable lithium batteries, reducing costs and improving structural stability, while maintaining environmental friendliness.
Implementation Method 1
subjecting the transition metal hydroxide precursor to a primary heat treatment at about 400° C. to about 600° C. for about 0.5 hour to about 20 hours to prepare a transition metal composite oxide precursor
Implementation Method 2
drying a hydrated lithium salt having an average particle diameter (D50) of about 400 μm to 600 μm to obtain a resultant
Implementation Method 3
performing a secondary heat treatment on the second mixture to prepare a nickel-based lithium transition metal oxide
Data Source
AI summary
A method of preparing a positive active material involves mixing a nickel compound, a cobalt compound, and optionally a metal compound to obtain a first mixture, subjecting the first mixture to a co-precipitation reaction to obtain a first resulting product, washing with water, filtering and drying the first resulting product to prepare a transition metal hydroxide precursor, subjecting the transition metal hydroxide precursor to a primary heat treatment to prepare a transition metal composite oxide precursor, mixing the transition metal composite oxide precursor and a dehydrated lithium salt to obtain a second mixture, and performing a secondary heat treatment on the second mixture to prepare a nickel-based lithium transition metal oxide. The dehydrated lithium salt is prepared by drying a hydrated lithium salt having an average particle diameter (D50) of about 400-600 μm and then pulverizing the resultant to have a D50 of about 3-30 μm.