Manganese-Based Positive Electrode Porosity and Coating for High-Temperature Stability
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Solution Overview
Problem
Manganese-based lithium secondary batteries face degradation due to manganese release during charging and discharging, especially at high temperatures, leading to increased resistance and reduced performance, which hinders the development of high-performance batteries with improved high-temperature storage and cycle characteristics.
Innovation Solution
A positive electrode with a manganese-based active material having a porosity of 30% to 35%, represented by the chemical formula xLi2MnO3·(1-x)LiMO2, where 0<x<1 and M is Al, Mg, Mn, Ni, Co, Cr, or Fe, is used, along with a binder and conductive material, to minimize manganese release and enhance high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manganese-based positive electrode active material is used, then cost and resource availability are improved, but manganese release during charging and discharging causes battery degradation and performance deterioration
Solution Approach 1:
A coating layer comprising at least one of a metal oxide, metal hydroxide, metal carbonate, or metal phosphate is formed on the surface of the positive electrode active material particles. This coating layer acts as an intermediary barrier that prevents direct contact between the manganese-based active material and the electrolyte solution, thereby suppressing manganese release while maintaining the cost and resource availability benefits of manganese-based materials
2Temperature
If high temperature storage is performed, then battery performance is improved, but manganese release increases causing faster electrolyte decomposition and resistance increase
Solution Approach 1:
The coating layer serves as a protective intermediary that remains stable at high temperatures and prevents manganese release even under elevated temperature conditions, thereby enabling high temperature storage without the harmful effects of accelerated manganese dissolution and electrolyte decomposition
Solution Approach 2:
The coating layer changes the surface properties of the positive electrode active material, creating a stable interface that resists thermal degradation and prevents manganese release at high temperatures, thereby transforming the thermal stability parameter of the electrode material
3Productivity
If manganese releases into electrolyte solution, then charging and discharging process continues, but manganese precipitation on negative electrode causes electrolyte decomposition and resistance increase
Solution Approach 1:
The coating layer on the positive electrode active material particles acts as a barrier that prevents manganese release into the electrolyte solution during charging and discharging, thereby eliminating the source of manganese that would otherwise precipitate on the negative electrode and cause electrolyte decomposition and resistance increase
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 solution reduces gas generation and transition metal precipitation, improving safety and resistance characteristics, thereby enhancing high-temperature storage and cycle performance of lithium secondary batteries.
Implementation Method 1
by the intercalation of lithium ions from a positive electrode active material to a negative electrode active material
Implementation Method 2
deintercalation for discharge
Implementation Method 3
when the released manganese substance is precipitated on the surface of a negative electrode active material
Implementation Method 4
the electrolyte solution decomposes fast in the negative electrode active material by a reduction reaction with electrons
Data Source
AI summary
The present disclosure relates to a positive electrode for a lithium secondary battery including an electrode current collector, and a positive electrode active material layer coated on at least a part of the electrode current collector, wherein the positive electrode active material layer includes a manganese-based positive electrode active material, and a porosity is from 30% to 35%, to improve high-temperature storage characteristics and high-temperature cycle characteristics.