Lithium-Rich Manganese Oxide Activation via Controlled Charge Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The generation of oxidizing gases during the high-voltage activating step in lithium secondary batteries using lithium-rich manganese-based oxides leads to increased resistance, pressure buildup, and stability issues, limiting charge/discharge capacity.
Innovation Solution
A method for manufacturing lithium secondary batteries involving the use of lithium-rich manganese-based oxide with specific manganese and lithium ratios, followed by controlled charging and discharging to form a Li/Li dumbbell structure, with a charge end point set at 1.10 < Y/X ≤ 1.13, where Y/X is the charge capacity to estimated capacity ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-voltage activating step (4.4V or more) is performed to achieve high capacity, then charge capacity is improved, but oxidizing gas generation increases significantly
Solution Approach 1:
The patent changes the voltage parameter from conventional high voltage (4.4V or more) to a specific range (3.8V to 4.2V) to suppress oxidizing gas generation while maintaining adequate charge capacity. This parameter optimization resolves the contradiction by finding a voltage level that balances capacity utilization with gas generation suppression.
Solution Approach 2:
The patent performs multiple activating steps with progressively increasing voltage limits rather than a single high-voltage step. The voltage limit is increased in subsequent steps only if gas generation in the previous step was within the specified range (10-50 mL), allowing partial activation at lower voltages first to stabilize the structure before higher voltage activation.
2Quantity of substance
If high-voltage activating step is performed, then lithium ion utilization is improved, but resistance of positive electrode increases significantly
Solution Approach 1:
The patent uses periodic activating steps with rest periods between them. Each activating step is followed by a rest period during which the battery is stored at a specific voltage range, allowing the positive electrode structure to stabilize and reducing cumulative resistance increase while still achieving progressive lithium ion utilization.
Solution Approach 2:
The patent performs multiple activating steps with progressively increasing voltage limits rather than a single high-voltage step. The voltage limit is increased in subsequent steps only if gas generation in the previous step was within the specified range, allowing partial activation at lower voltages first to minimize resistance increase while still achieving adequate lithium ion utilization.
3Use of energy by moving object
If high-voltage activating step is performed, then energy density is improved, but pressure inside cell increases causing safety issues
Solution Approach 1:
The patent changes the voltage parameter from conventional high voltage (4.4V or more) to a specific range (3.8V to 4.2V) and controls the charge capacity ratio to 10-50 mL, which suppresses oxidizing gas generation and consequently reduces pressure buildup inside the cell while maintaining adequate energy density.
Solution Approach 2:
The patent performs multiple activating steps with progressively increasing voltage limits rather than a single high-voltage step. The voltage limit is increased in subsequent steps only if gas generation in the previous step was within the specified range, allowing gradual energy density improvement while suppressing excessive pressure buildup through controlled activation.
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
Suppresses the generation of oxidizing gases, stabilizes the battery structure, and maintains charge capacity by adjusting the charge end point during activation, enhancing battery performance and safety.
Implementation Method 1
charging and discharging the battery cell at least one or more times to activate the battery
Implementation Method 2
formation/desorption of oxygen radicals occurs through an oxygen redox reaction, and large amounts of oxidizing gases such as CO, CO2, and O2 may be generated due to side reactions between oxygen radicals and the electrolyte
Implementation Method 3
ending the charging when a ratio (Y/X) of the charge capacity (mAh/g) (Y) of a secondary battery to the estimated capacity (mAh/g) (X) of a positive electrode active material at a point where all lithium ions contained in the lithium-rich manganese-based oxide form a Li/Li dumbbell structure
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to a method for manufacturing a lithium secondary battery, the method comprising the steps of: preparing a battery cell including a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode includes lithium-rich manganese-based oxide in which the content of manganese in all metals excluding lithium is greater than 50 mol%, and a ratio of the number of moles of lithium to the number of moles of all metals excluding lithium(Li/Me) is greater than 1; and charging and discharging the battery cell at least one or more times to activate the battery, wherein the activating step includes ending the charging when a ratio(Y/X) of the charge capacity(mAh/g) (Y) of a secondary battery to the estimated capacity(mAh/g) (X) of a positive electrode active material at a point where all lithium ions contained in the lithium-rich manganese-based oxide form a Li/Li dumbbell structure corresponds to 1.10 < Y/X ≤ 1.13.