Lithium Secondary Battery Cycling With Periodic High-Voltage Activation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries with Mn-rich positive electrode materials face high capacity and energy deterioration as the cycle progresses, requiring improvements in charge/discharge protocols to enhance their life characteristics without altering the battery design.
Innovation Solution
A method for charging and discharging lithium secondary batteries that includes alternating high voltage cycles, activating the rock-salt phase (Li2MnO3) at higher voltages to intercalate excess lithium ions into the negative electrode, thereby improving capacity retention and life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional charging and discharging methods are used, then the battery can operate normally, but the capacity and energy deteriorate rapidly as cycles progress
Solution Approach 1:
The patent applies periodic action by implementing alternating charge/discharge cycles with varying voltage ranges. The method periodically switches between a first cycle (lower voltage range for stability) and a second cycle (higher voltage range for capacity activation), which periodically activates the rock-salt phase to improve long-term capacity retention without causing continuous degradation from high voltage stress.
Solution Approach 2:
The patent changes the voltage parameter dynamically by implementing two distinct charge/discharge voltage ranges. The first cycle uses a conservative voltage range to minimize degradation, while the second cycle uses a higher voltage range to activate additional capacity in the rock-salt phase. This parameter variation allows the battery to access more capacity while managing degradation through controlled stress conditions.
2Quantity of substance
If high voltage charging is applied continuously, then additional capacity can be activated, but the battery life is reduced due to excessive stress
Solution Approach 1:
The patent uses periodic action to alternate between high-voltage and low-voltage charging cycles. The high-voltage second cycle activates additional capacity in the rock-salt phase, while the low-voltage first cycle allows recovery and reduces cumulative stress. This periodic alternation enables capacity activation while preserving battery life through rest periods at lower stress levels.
Solution Approach 2:
The patent applies preliminary action by performing activation cycles at higher voltage to develop capacity in the rock-salt phase before transitioning to normal operation cycles. The initial high-voltage cycles prepare the electrode structure by activating the rock-salt phase and establishing stable lithium ion pathways, which then enables subsequent cycles to maintain capacity with reduced degradation.
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
This method significantly enhances the energy retention rate and life of lithium secondary batteries by incorporating high voltage cycles at fixed intervals, reducing voltage drop and maintaining capacity over cycles without changing materials or structure.
Implementation Method 1
Charging and discharging are performed through a process in which lithium ions emitted from the positive electrode active material are intercalated into the negative electrode active material during charge and are deintercalated again during discharge
Implementation Method 2
the rock-salt phase (Li2MnO3) is further activated when driving at high voltage, which makes it possible to develop additional capacity
Data Source
AI summary
A method for charging and discharging a lithium secondary battery includes: a first step of preparing a lithium secondary battery including a positive electrode, a negative electrode and an electrolyte, with the positive electrode comprising lithium-rich manganese-based oxide having a manganese content of 50 mol % or more among all metals excluding lithium as a positive electrode active material; a second step of charging the lithium secondary battery from the lower limit voltage to the first upper limit voltage and discharging the lithium secondary battery from the first upper limit voltage to the lower limit voltage; and a third step of charging the lithium secondary battery from the lower limit voltage to the second upper limit voltage and discharging the lithium secondary battery from the second upper limit voltage to the lower limit voltage, wherein the second upper limit voltage is 0.05V to 0.20V higher than the first upper limit voltage, and the second step and the third step are alternately and repeatedly performed on the basis of a fixed number of times of cycles.