Secondary Battery Charging with SOH-Based Lithium Supplementation
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Solution Overview
Problem
Secondary batteries face challenges in maintaining energy density due to irreversible lithium loss during the first charging process, leading to reduced cycle life and performance issues such as phase transitions and increased Directive Current Resistance (DCR).
Innovation Solution
A lithium-supplementing method that detects the State Of Health (SOH) of the secondary battery and supplements lithium when necessary, performing a controlled charging process to maintain active lithium content, thereby extending cycle life and improving energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a first charging process is performed on a secondary battery, then the battery can be charged, but irreversible lithium loss occurs due to SEI film formation on the negative electrode
Solution Approach 1:
The patent introduces a lithium supplementing material into the battery system before normal operation begins. This material serves as a preliminary lithium reservoir that can compensate for the inevitable lithium loss during SEI film formation, ensuring the battery maintains sufficient active lithium content throughout its cycle life.
Solution Approach 2:
The patent changes the voltage parameter by performing a second charging process at a voltage higher than the first charging voltage. This high-voltage charging activates the lithium supplementing material to release lithium ions, thereby compensating for the lithium loss that occurred during initial charging and cycling.
2Reliability
If lithium is supplemented during cycling, then active lithium content is maintained, but material phase transition and increased DCR may occur
Solution Approach 1:
The patent carefully controls the voltage parameter during lithium supplementation, using a second charging voltage that is higher than the first but still within a safe range (e.g., 4.4V-4.8V). This controlled parameter change activates the lithium supplementing material while avoiding excessive voltage that would cause material phase transitions and electrolyte decomposition.
Solution Approach 2:
The patent implements a monitoring mechanism that detects the State of Health (SOH) of the battery and determines when lithium supplementation is needed. This feedback-based approach ensures lithium is supplemented only when necessary, preventing over-supplementation that could lead to harmful effects while maintaining optimal lithium content for extended cycle life.
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 supplements lithium, reducing irreversible capacity loss, improving cycling performance, and enhancing the energy density of secondary batteries by maintaining active lithium levels and avoiding issues like phase transitions and gas generation.
Implementation Method 1
activating the lithium-supplementing material when the SOH1 is less than or equal to a first threshold, to supplement lithium for the secondary battery
Data Source
AI summary
A charging method for a secondary battery including a lithium-supplementing material. The method includes acquiring a first state of health of the secondary battery in response to the secondary battery being at a preset charging node, activating the lithium-supplementing material in response to the first state of health being less than or equal to a first threshold to supplement lithium for the secondary battery, performing a charging process on the secondary battery, determining a second state of health of the secondary battery based on a working parameter of the secondary battery in the charging process, and charging the secondary battery in response to the second state of health being greater than a second threshold.