Battery Charging Cutoff Strategy for High-Nickel Gas Suppression
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Solution Overview
Problem
Lithium-ion batteries with high-nickel positive electrode active materials experience high-temperature cyclic gas generation due to H2↔H3 phase transformation, leading to oxygen release and electrolyte oxidation, which poses a risk and results in capacity decay.
Innovation Solution
A charging method that reduces the charge cut-off voltages across multiple cycle stages, with each stage having a specific cut-off voltage, to mitigate the stress on the positive electrode active material and prevent gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-voltage charging is used to achieve high energy density, then charging efficiency is improved, but cyclic gas generation increases due to H2↔H3 phase transformation and oxygen release
Solution Approach 1:
The patent applies dynamic charging strategy by adjusting charging current and voltage thresholds based on battery state. The charging current is dynamically reduced when approaching high-voltage regions (above 4.2V) where H2↔H3 phase transformation occurs, and charging is paused when gas generation threshold is detected. This dynamic adjustment resolves the contradiction by maintaining high charging efficiency in safe voltage regions while preventing gas generation in high-risk voltage regions.
Solution Approach 2:
The patent implements feedback control by monitoring battery voltage, current, and gas generation indicators in real-time. When the battery voltage reaches 4.2V or gas generation threshold is approached, the system automatically reduces charging current or pauses charging. This feedback mechanism allows the system to achieve high energy density through high-voltage charging while preventing cyclic gas generation by responding to real-time battery conditions.
2Quantity of substance
If high-nickel positive electrode active material is used to achieve high energy density, then battery capacity is improved, but high-temperature cyclic gas generation and capacity decay occur
Solution Approach 1:
The patent changes operational parameters (charging voltage threshold, charging current, temperature thresholds) to prevent capacity decay in high-nickel batteries. By setting voltage threshold at 4.2V and reducing charging current when approaching this threshold, the patent prevents H2↔H3 phase transformation and oxygen release that cause capacity decay. This parameter control allows the battery to achieve high capacity from high-nickel material while maintaining capacity stability through controlled charging conditions.
Solution Approach 2:
The patent applies beforehand cushioning by implementing protective charging measures before capacity decay occurs. The charging system proactively reduces current or pauses charging when voltage approaches 4.2V or when gas generation indicators are detected, preventing the H2↔H3 phase transformation and oxygen release that would otherwise cause capacity decay. This preventive approach allows high-nickel batteries to achieve high capacity while maintaining long-term reliability.
3Object-generated harmful factors
If surface coating and film-forming additives are used to protect the positive electrode, then gas generation is reduced, but dynamic performances deteriorate with temperature rise and poor low-temperature discharging
Solution Approach 1:
The patent replaces chemical protection methods (surface coating and film-forming additives) with an electrical control mechanism. Instead of using chemical layers to prevent gas generation, the patent uses voltage threshold control (4.2V) and dynamic current adjustment to prevent H2↔H3 phase transformation. This substitution eliminates the negative effects of coating and additives on dynamic performance while still preventing gas generation through electrical parameter control.
Solution Approach 2:
The patent changes the approach from chemical modification to electrical parameter control. By adjusting charging voltage threshold to 4.2V and dynamically controlling charging current based on real-time battery state, the patent prevents gas generation without using surface coating or film-forming additives. This parameter-based control maintains excellent dynamic performance including temperature response and low-temperature discharging capability while still preventing cyclic gas generation.
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 alleviates the expansion of the electrochemical device and slows down capacity decay without affecting the user experience, by gradually reducing the charging stress on the positive electrode active material.
Implementation Method 1
A lithium-ion battery is also often referred to as a lithium battery, and is an electrochemical device that can be charged and discharged
Data Source
AI summary
A charging method for an electrochemical device includes the following steps: in a first cycle stage, a charging stage of the first cycle stage has a first cut-off voltage; and in a second cycle stage, a charging stage of the second cycle stage has a second cut-off voltage, and the second cut-off voltage is less than the first cut-off voltage. According to the charging method for an electrochemical device, an electronic device, and a readable storage medium provided in the present application, the risk of cyclic gas generation of the electrochemical device can be effectively prevented, and the service life of the electrochemical device can be improved.