Polyimide Nanofilm Coated Positive Electrode for Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face rapid lifespan decrease due to side reactions between the positive electrode and electrolyte, especially under high voltage and high temperature conditions, with existing oxide coating technologies limiting surface modification and causing ion conductivity issues.
Innovation Solution
A surface-coated positive electrode active material with a nanofilm comprising polyimide and conductive nanoparticles, such as antimony tin oxide, indium tin oxide, or zinc oxide, is applied to prevent direct contact with the electrolyte, enhancing lithium ion migration and electron conductivity while surrounding the entire surface of the active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide coating layer is applied on the surface of a positive electrode active material, then stability of the positive electrode active material is enhanced, but the coating layer is one type of an ion insulation layer in which lithium ion migration is difficult, causing ion conductivity decrease
Solution Approach 1:
The patent applies a composite coating layer comprising polyimide and conductive metal oxide nanoparticles. The polyimide provides stability and protection, while the conductive metal oxide nanoparticles (such as indium tin oxide, antimony tin oxide, or zinc oxide) provide ion conductivity pathways. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both stability and ion conductivity.
Solution Approach 2:
The coating layer is designed with non-uniform distribution of conductive metal oxide nanoparticles within the polyimide matrix. This creates local conductive pathways for lithium ion migration while maintaining the overall protective and stabilizing function of the polyimide coating. The local quality variation allows different regions of the coating to perform different functions.
2Object-generated harmful factors
If a nanofilm including polyimide and conductive nanoparticles is formed on the positive electrode active material surface, then lithium ion migration is enhanced and conductivity is improved, but the side reaction between positive electrode active material and electrolyte must be suppressed
Solution Approach 1:
The composite coating of polyimide and conductive metal oxide nanoparticles simultaneously addresses both requirements. The polyimide forms a protective barrier that suppresses side reactions with the electrolyte, while the conductive metal oxide nanoparticles create pathways for lithium ion migration, enhancing conductivity. The synergistic effect of these two materials resolves the contradiction between preventing side reactions and maintaining conductivity.
Solution Approach 2:
The coating layer acts as an intermediary between the positive electrode active material and the electrolyte. It provides a controlled interface that allows beneficial lithium ion migration while blocking harmful direct contact between the active material and electrolyte, thus suppressing side reactions. The conductive nanoparticles within the coating mediate the ion transport process.
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
This solution significantly improves the lifespan and conductivity of lithium secondary batteries under high temperature and high voltage conditions, providing enhanced safety and maintaining consistent current and voltage distribution during charge-discharge cycles.
Implementation Method 1
a surface coated positive electrode active material prepared by forming a nanofilm including polyimide and conductive nanoparticles on the surface of the positive electrode active material
Implementation Method 2
the oxide coating layer is one type of an ion insulation layer in which lithium ion migration is difficult, and may cause an ion conductivity decrease
Implementation Method 3
lithium ion migration is difficult
Data Source
Figure 1(a)~3(b)
Figure 4
AI summary
The present invention relates to a surface coated positive electrode active material, a preparation method thereof, and a lithium secondary battery including the same. More specifically, it relates to a positive electrode active material of which surface is coated with a nanofilm including polyimide (PI) and conductive nanoparticles, a preparation method thereof, and a lithium secondary battery including the same. The positive electrode active material of which surface is coated with the nanofilm according to the present invention is capable of preventing direct contact of the positive electrode active material with an electrolyte thereby suppressing a side reaction between the positive electrode active material and the electrolyte, and as a result, a lifespan property of a lithium secondary battery using a positive electrode including the same may be significantly improved, and particularly, a lifespan property and conductivity are capable of being enhanced under a high temperature and high voltage condition.