Lithium-Rich Cathode Activation to Limit Battery Gas Generation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries with lithium-rich manganese-based oxides face issues of excessive gas generation and metal elution during high-voltage activation, leading to reduced capacity and life characteristics.
Innovation Solution
A manufacturing method for lithium secondary batteries involving a preliminary cell with a positive electrode containing lithium-rich manganese-based oxide, where the charging capacity ratio from 4.3V to the cut-off voltage is limited to 0.63 or less, along with specific particle size and surface area ranges for the active material, and a controlled charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-voltage activation (4.3V or more) is performed to achieve high capacity, then capacity is improved, but gas generation and metal elution increase
Solution Approach 1:
A coating layer is formed on the surface of the lithium-rich manganese-based oxide positive electrode active material before battery assembly. This preliminary protective action prevents oxygen desorption and metal elution during subsequent high-voltage activation, allowing capacity improvement without excessive gas generation
Solution Approach 2:
A coating layer acts as an intermediary between the positive electrode active material and the electrolyte. This intermediate layer suppresses direct harmful interactions while allowing ionic transport, thereby enabling high-voltage operation without excessive gas generation and metal elution
2Object-generated harmful factors
If activation voltage is lowered to reduce gas generation, then gas generation is reduced, but abnormal capacity increase and additional gas generation occur during battery operation
Solution Approach 1:
The coating layer is applied in advance to enable proper activation at high voltage, preventing the need for low-voltage activation and subsequent abnormal capacity increase during battery operation
Solution Approach 2:
The coating layer serves as a stable intermediary that enables reliable high-voltage activation, preventing the abnormal capacity increase and additional gas generation that would otherwise occur during battery operation
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
Minimizes gas generation and metal elution, improving processability, stability, capacity, and life characteristics of the battery.
Implementation Method 1
achieves capacity by simultaneously utilizing not only the cation redox reaction of the transition metal but also the anion redox reaction using oxygen
Implementation Method 2
achieves capacity by simultaneously utilizing not only the cation redox reaction of the transition metal but also the anion redox reaction using oxygen
Implementation Method 3
in the process of such a high-voltage activation, oxygen desorption may occur, which may result in generation of excessive gas
Data Source
AI summary
The present disclosure relates to a manufacturing method of a lithium secondary battery comprising: a step(S1) of manufacturing a preliminary cell which comprises a positive electrode containing a positive electrode active material, a negative electrode, a separator and an electrolyte; and a step (S2) of charging the preliminary cell to a charging cut-off voltage and discharging to activate the preliminary cell, wherein: the positive electrode active material includes a lithium-rich manganese-based oxide containing 50 mol% or more of manganese(Mn) among all metals excluding lithium, and having a molar ratio of lithium to all metals excluding lithium (Li/Me) exceeding 1, the charging cut-off voltage is more than 4.3V, and the activating step is performed so that the ratio (B/A) of the charging capacity(B) in the range from 4.3V to the charging cut-off voltage to the total charging capacity(A) when the preliminary cell is charged to the charging cut-off voltage is 0.63 or less.