Iodine-Coated Positive Electrode Material for High-Temperature Cycling
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Solution Overview
Problem
Lithium-ion secondary batteries with high nickel content face challenges in maintaining high-temperature cycle characteristics and stability due to gas generation and resistance increases, limiting their application in high-capacity batteries.
Innovation Solution
Incorporating an iodine-containing material with an oxidation number of +3 to +7, such as periodate ions, onto the surface of lithium transition metal oxides in the positive electrode active material to form a coating that inhibits gas generation and resistance increases, thereby enhancing cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content is used to increase battery capacity, then energy density is improved, but high-temperature cycle characteristics deteriorate due to gas generation and resistance increases
Solution Approach 1:
The patent applies composite materials by forming a coating layer containing iodine on the surface of the lithium transition metal oxide particles. This coating layer composite structure combines the high-capacity lithium transition metal oxide core with an iodine-containing protective shell, where the iodine species (with oxidation number +3 to +7) suppresses gas generation and resistance increases during high-temperature cycling, thus resolving the contradiction between high capacity and high-temperature stability
Solution Approach 2:
The patent utilizes parameter changes by controlling the oxidation number of iodine to be +3 to +7 in the coating layer. This specific oxidation state range optimizes the protective function of the iodine-containing material, enabling it to effectively inhibit gas generation and resistance increases while maintaining electrochemical performance, thereby improving high-temperature cycle characteristics without sacrificing capacity
2Quantity of substance
If high nickel content is used to increase battery capacity, then energy density is improved, but resistance increases during cycling
Solution Approach 1:
The iodine-containing coating layer forms a composite structure that acts as a protective barrier, preventing direct contact between the lithium transition metal oxide and the electrolyte. This composite material approach suppresses resistance increases during cycling while preserving the high capacity characteristics of the nickel-rich positive electrode active material
3Quantity of substance
If high nickel content is used to increase battery capacity, then energy density is improved, but gas generation occurs during cycling
Solution Approach 1:
The coating layer containing iodine with oxidation number +3 to +7 forms a stable composite structure on the particle surface that suppresses gas generation during high-temperature cycling. The iodine-containing material acts as a protective barrier that prevents harmful gas evolution while maintaining the high capacity performance of the underlying lithium transition metal oxide
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 iodine-containing material improves the high-temperature cycle characteristics and electrical conductivity of lithium-ion secondary batteries, reducing degradation and maintaining capacity retention over repeated charge/discharge cycles.
Implementation Method 1
an iodine-containing material at least partially covering the lithium transition metal oxide
Implementation Method 2
the iodine-containing material having iodine having an oxidation number of +3 to +7
Data Source
AI summary
A positive electrode active material, a method of making the same, and a lithium-ion secondary battery including the same are disclosed herein. A lithium-ion secondary battery including the positive electrode active material can have excellent cycle characteristics at high temperature. In some embodiments, a positive electrode active material a lithium transition metal oxide, and an iodine-containing material at least partially covering the lithium transition metal oxide, where the iodine-containing material contains iodine having an oxidation number of +3 to +7.