Lithium Ion Battery High Rate Deterioration Recovery via dQ/dV Voltage Control
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Solution Overview
Problem
Lithium ion batteries for vehicles suffer from high rate deterioration, which is difficult to recover without additional devices, as existing techniques require heaters or electrolyte vibration, complicating the battery system structure.
Innovation Solution
A battery system with a voltage converter and control unit that calculates a deterioration index based on lithium ion concentration distribution, adjusting the battery voltage to a specific peak voltage derived from the positive electrode active material's dQ/dV characteristic curve, allowing for repeated charging/discharging within a predetermined voltage range to reduce bias and recover high rate deterioration without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heater is added to warm the battery to recover high rate deterioration, then the deterioration recovery effect is achieved, but the device complexity increases
Solution Approach 1:
The battery system uses its own voltage converter to perform controlled charge/discharge cycles that automatically recover high rate deterioration. The control unit monitors the deterioration index and triggers self-recovery operations without external intervention, eliminating the need for heaters or other additional devices.
Solution Approach 2:
The invention changes the voltage parameter during controlled charge/discharge cycles to specific ranges that induce structural changes in the positive electrode active material. By adjusting voltage parameters rather than temperature, the system achieves deterioration recovery without requiring thermal management equipment.
2Reliability
If a vibration device is added to vibrate the electrolyte to recover high rate deterioration, then the deterioration recovery effect is achieved, but the device complexity increases
Solution Approach 1:
The invention replaces the mechanical vibration system with an electrical control system. Instead of using physical vibration to move lithium ions, the system uses controlled voltage changes during charge/discharge cycles to achieve the same effect, eliminating the need for vibration devices.
Solution Approach 2:
The battery system performs self-recovery through controlled charge/discharge operations managed by the control unit. The system monitors its own deterioration index and executes recovery protocols using its existing voltage converter, without requiring external vibration equipment.
3Reliability
If the battery voltage is controlled to fall within a specific range including peak voltage, then high rate deterioration is recovered, but the control complexity increases
Solution Approach 1:
The control unit continuously monitors the deterioration index calculated from voltage characteristics and adjusts the charge/discharge control accordingly. When the deterioration index exceeds a threshold, the system activates controlled voltage cycling; when it falls below the threshold, normal operation resumes. This feedback mechanism automates the control process without requiring complex manual intervention.
Solution Approach 2:
The system changes voltage parameters to specific ranges that correspond to peak voltages on dQ/dV curves. These voltage changes induce structural transformations in the positive electrode material that recover deterioration. The control logic monitors voltage characteristics and adjusts parameters automatically based on real-time battery state.
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 approach effectively recovers high rate deterioration of lithium ion batteries using a simple structure, reducing internal resistance and extending battery life without the need for extra hardware, such as heaters or vibration devices.
Implementation Method 1
the specific voltage is a peak voltage on a dQ/dV voltage characteristic curve, the peak voltage being derived from structural change of a positive electrode active material contained in the electrode assembly
Implementation Method 2
a positive electrode is thus shrunk due to structural change of the positive electrode active material, and hence a negative electrode relatively expands. Owing to the expansion of the negative electrode, an electrolyte is absorbed by the negative electrode, resulting in reducing the bias in the lithium ion concentration distribution within the electrode assembly
Data Source
AI summary
A battery system includes a battery that is a lithium ion battery including an electrode assembly containing a positive electrode active material. An ECU calculates a deterioration index value ΣD corresponding a degree of progress of high rate deterioration, and when the deterioration index value ΣD exceeds a threshold value, controls a power converter or a PCU to cause a voltage of the battery to fall within a voltage range including a specific voltage. The specific voltage is a peak voltage on a dQ/dV voltage characteristic curve, the peak voltage being derived from structural change of the positive electrode active material. The dQ/dV voltage characteristic curve is a curve indicating a relationship between dQ/dV that is a ratio of a change dQ of a stored electricity amount to a change dV of the voltage of the battery, and the voltage of the battery.