Lithium-Rich Manganese Oxide Cell Activation Under Pressurization
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Solution Overview
Problem
Lithium secondary batteries using lithium-rich manganese-based oxide experience abnormal capacity increase and excessive gas generation during operation due to the high-voltage activation process, which can lead to lithium precipitation and electrode degradation.
Innovation Solution
A method for manufacturing lithium secondary batteries involving lithium-rich manganese-based oxide, where the battery cells are activated under specific conditions, including charging in constant current-constant voltage mode and pressurization, to minimize gas generation and prevent abnormal capacity increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-voltage activation process (4.4V or higher) is used to activate Li2MnO3 phase, then capacity is improved, but gas generation and transition metal elution occur
Solution Approach 1:
A coating layer is formed on the surface of lithium-rich manganese-based oxide particles before battery assembly. This coating layer acts as a protective barrier that prevents direct contact between the high-voltage activation process and the bulk material, thereby suppressing gas generation and transition metal elution while still allowing sufficient lithium ion transport to activate the Li2MnO3 phase and achieve high capacity.
2Object-generated harmful factors
If activation voltage is lowered to reduce gas generation, then gas generation is suppressed, but Li2MnO3 phase activation is insufficient causing abnormal capacity increase during operation
Solution Approach 1:
The invention modifies the surface properties of lithium-rich manganese-based oxide by forming a coating layer with specific composition and structure. This coating layer changes the interfacial parameters between the electrode material and electrolyte, enabling sufficient activation of Li2MnO3 phase at reduced voltages while preventing abnormal capacity increase during subsequent battery operation.
3Quantity of substance
If high-voltage activation is performed, then Li2MnO3 phase is activated to achieve high capacity, but transition metal elution occurs
Solution Approach 1:
A coating layer is introduced as an intermediary between the lithium-rich manganese-based oxide and the electrolyte. This coating layer mediates the interaction during high-voltage activation, allowing lithium ion transport necessary for Li2MnO3 phase activation while blocking the direct contact that would otherwise cause transition metal elution into the electrolyte.
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 method effectively suppresses abnormal capacity increase and gas generation during battery operation, enhancing the stability and longevity of the lithium secondary batteries by ensuring proper activation and gas discharge.
Implementation Method 1
charging and discharging the battery cell under pressurization to activate the battery
Implementation Method 2
charging and discharging the battery cell under pressurization to activate the battery
Data Source
AI summary
A method for manufacturing a lithium secondary battery includes preparing a battery cell, charging and discharging the battery cell under pressurization to activate the battery, and then charging is performed in a constant voltage mode. The battery cell includes a positive electrode, a negative electrode and an electrolyte, with the positive electrode containing lithium-rich manganese-based oxide in which the content of manganese in all metals excluding lithium is greater than 50 mol %, and the ratio of the number of moles of lithium to the number of moles of all metals excluding lithium (Li/Me) is greater than 1. The charging and discharging the battery cell under pressurization activates the battery. In the activating, the charging is performed in constant current mode until the charge cut-off voltage, and then the charging is performed in a constant voltage mode, and the charge cut-off voltage is greater than 4.35V.