Positive Electrode Active Material Doping for High-Voltage Cycle Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving stable charge and discharge cycles, high capacity, reliability, safety, and cost effectiveness due to the instability of positive electrode active materials at high potentials and temperatures.
Innovation Solution
A method for forming a positive electrode active material involves mixing a cobalt source with an additive element source, such as gallium or aluminum, in acidic and alkaline solutions to create a cobalt compound, which is then combined with a lithium source and heated to form a composite oxide, with specific heating temperatures and atmospheres to enhance stability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode is charged to a high potential to achieve high capacity, then the charge and discharge capacity is improved, but the crystal structure stability deteriorates causing significant deterioration in charge and discharge cycles
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the positive electrode active material surface before the material is subjected to high potential charging. This coating layer, formed through preliminary chemical treatment with specific reagents, prevents crystal structure deterioration during subsequent high-capacity charging cycles, thus resolving the contradiction between achieving high capacity and maintaining structural stability.
Solution Approach 2:
The patent employs composite materials by combining the positive electrode active material with a protective coating layer formed through chemical treatment. This composite structure allows the core material to provide high capacity while the outer coating layer maintains crystal structure stability during charging and discharging, effectively resolving the technical contradiction between capacity and reliability.
2Ease of manufacture
If conventional synthesis methods are used to produce positive electrode active materials, then the manufacturing process is simple, but the charge and discharge cycle performance and reliability are insufficient
Solution Approach 1:
The patent introduces a preliminary chemical treatment step where the positive electrode active material is treated with specific reagents to form a protective coating layer. This preliminary action enhances the material's cycle performance and reliability without significantly complicating the overall manufacturing process, as the treatment can be integrated into existing synthesis workflows.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical environment during synthesis through the use of specific reagents and controlled treatment conditions. These parameter changes (chemical composition, treatment time, temperature) transform the surface properties of the active material to improve cycle performance while maintaining manufacturing feasibility.
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 results in a positive electrode active material that is stable at high potentials and temperatures, with improved charge and discharge cycle performance, high capacity, and enhanced safety, leading to more reliable secondary batteries.
Implementation Method 1
a cobalt source and an additive element source are mixed to form an acidic solution; the acidic solution and an alkaline solution are made to react to form a cobalt compound
Implementation Method 2
the cobalt compound and a lithium source are mixed to form a mixture; and the mixture is heated
Data Source
AI summary
A novel method for forming a positive electrode active material is provided. In the method for forming a positive electrode active material, a cobalt source and an additive element source are mixed to form an acidic solution; the acidic solution and an alkaline solution are made to react to form a cobalt compound; the cobalt compound and a lithium source are mixed to form a mixture; and the mixture is heated. The additive element source is a compound containing one or more selected from gallium, aluminum, boron, nickel, and indium.