Battery Charge Control Device for Lithium Ion Safety
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Solution Overview
Problem
Lithium ion secondary batteries face the risk of lithium metal precipitation on the negative electrode during high-rate charging, high state of charge, long-term continuous charging, or charging at low temperatures, leading to overheating and performance reduction.
Innovation Solution
A battery charge/discharge control device that adjusts input power to prevent the negative electrode potential from reaching the lithium reference potential, using a power adjustment unit that calculates and limits the charge current based on charge history, temperature, and state of charge to avoid lithium precipitation, while also considering battery degradation and voltage limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-rate charging is applied to lithium ion secondary batteries, then charging speed and productivity are improved, but lithium metal precipitates on the negative electrode causing overheating and performance reduction
Solution Approach 1:
The patent implements dynamic charge rate adjustment by continuously monitoring battery state (temperature, charge level, current) and adapting the charging current in real-time. The control device reduces charge rate when approaching critical thresholds and allows higher rates when conditions permit, resolving the contradiction between charging speed and safety through adaptive dynamic control rather than fixed rate charging
Solution Approach 2:
The system employs multiple feedback mechanisms including temperature sensors, voltage monitors, and current detectors that continuously feed battery state information back to the control device. This feedback loop enables the controller to adjust charging parameters dynamically, preventing lithium precipitation while maximizing charging speed within safe operating boundaries
2Duration of action of moving object
If continuous charge for a long period of time is applied, then battery capacity is fully utilized, but lithium metal precipitates on the negative electrode surface
Solution Approach 1:
The patent implements periodic charge interruptions or rate reductions during extended charging cycles. The control device monitors charge duration and automatically adjusts the charging profile by introducing rest periods or reducing current at specific intervals, preventing lithium metal accumulation while still achieving full battery utilization over time
Solution Approach 2:
The system performs preliminary assessment of battery state before initiating or continuing charge cycles. By evaluating temperature, charge level, and historical charge patterns in advance, the control device preemptively adjusts charging parameters to prevent conditions that would lead to lithium precipitation, ensuring safe extended charging operation
3Adaptability or versatility
If charging at low temperature is applied, then battery operation is maintained in cold conditions, but lithium metal precipitates on the negative electrode due to high resistance state
Solution Approach 1:
The patent dynamically changes charging parameters (current, voltage, rate) based on detected temperature conditions. When low temperature is detected, the control device automatically reduces charge rate and adjusts voltage profiles to compensate for increased resistance, preventing lithium precipitation while maintaining operational capability in cold environments
Solution Approach 2:
The system applies preliminary heating or pre-conditioning when cold temperature is detected before initiating full charging. By preemptively warming the battery or adjusting parameters to counteract cold-temperature effects, the control device prevents the high-resistance state that would otherwise cause lithium metal precipitation during charging in cold conditions
4Power
If charging from high state of charge is applied, then battery voltage and power output are improved, but lithium metal precipitates on the negative electrode
Solution Approach 1:
The patent implements partial charging control that deliberately limits charge to below 100% state of charge under certain conditions, or applies reduced charge rates when approaching high voltage thresholds. This partial action approach prevents lithium precipitation by avoiding the excessive voltage and current conditions that cause metal deposition, while still achieving sufficient power output for practical applications
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
Effectively suppresses overcharge and prevents lithium metal precipitation, thereby avoiding overheating and performance degradation of lithium ion secondary batteries.
Implementation Method 1
there is a possibility that a lithium (Li) metal precipitates on a surface of the negative electrode of a lithium ion secondary battery during use
Data Source
AI summary
A battery charge/discharge control device (20) includes an input-enabled power adjustment unit (40) having an input-enabled current value calculation unit (42) and an input power limit value calculation unit (44). The input-enabled current value calculation unit (42) uses a battery current value, a battery temperature value, and an estimated charge capacity value at the time “t” upon execution of detection, so as to obtain an input-enabled current value reduction amount per unit time during charge and an enabled current amount recovery amount per unit time when being left uncontrolled. Moreover, the input-enabled current value calculation unit (42) calculates an input-enabled current value Ilim(t) to a battery (10) according to the previously calculated input-enabled current value Ilim(t−1) which has been calculated previously or the only initially set input-enabled current value The input power limit value calculation unit (44) calculates the battery input power limit value so that the input current limit target value obtained in accordance with the input-enabled current value Ilim(t) is greater than an actual battery current value. Thus, the input-enabled power to the battery (10) is adjusted in accordance with the battery input power limit value.