Battery Pre-heating for Fast Charge Durability
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Solution Overview
Problem
Lithium-ion traction batteries in electric vehicles face durability issues due to temperature extremes and high charge/discharge rates, leading to reduced cycle life and increased resistance, especially when charged at low temperatures, which can result in metallic lithium plating and internal short circuits.
Innovation Solution
A battery controller that pre-heats the traction battery to a temperature between 35°C and 45°C before fast charging, allowing for increased charge rates while minimizing deleterious effects on cycle life and power capability, by inhibiting power transfer when temperatures exceed the upper threshold and activating cooling or heating systems accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast charging is performed at low temperatures, then charging speed is improved, but battery durability deteriorates due to metallic lithium plating and internal short circuits
Solution Approach 1:
The system performs preliminary heating of the battery to a predetermined temperature range (above 0°C and below 45°C) before initiating fast charging. This preliminary action ensures the battery is in an optimal temperature state to accept fast charging current without causing lithium plating, thereby enabling high-speed charging while protecting battery durability.
Solution Approach 2:
The system dynamically adjusts the battery temperature parameter by controlling heating and cooling operations based on the battery's current temperature state. By maintaining the temperature within the optimal range (above 0°C and below 45°C) before and during fast charging, the system optimizes charge reaction kinetics while preventing harmful effects, thus achieving both high charging speed and battery durability.
2Productivity
If battery temperature is elevated to improve charge reaction kinetics, then charging efficiency is improved, but battery durability worsens due to thermal degradation
Solution Approach 1:
The system optimizes the battery temperature parameter by heating the battery to a controlled temperature range (above 0°C and below 45°C) before fast charging. This parameter optimization improves charge reaction kinetics and charging efficiency while preventing thermal degradation and maintaining battery durability through precise temperature control.
Solution Approach 2:
The system continuously monitors the battery temperature and adjusts heating/cooling operations based on feedback from temperature sensors. This closed-loop control ensures the battery remains within the optimal temperature range during fast charging, maximizing charging efficiency while preventing excessive temperature rise that would harm battery durability.
3Reliability
If cooling is activated to maintain battery temperature below upper threshold, then battery safety is improved, but charging speed deteriorates due to reduced charge reaction kinetics
Solution Approach 1:
The system performs preliminary heating to bring the battery temperature into the optimal range (above 0°C and below 45°C) before fast charging begins. This preliminary action ensures that cooling operations are minimized or eliminated during charging, allowing maximum charging speed while maintaining battery safety through pre-established temperature control.
Solution Approach 2:
The system dynamically adjusts cooling operation based on real-time temperature monitoring. By activating cooling only when necessary to maintain the temperature below the upper threshold (45°C) and using minimal cooling intervention, the system preserves charging speed while ensuring battery safety through adaptive temperature management.
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 extends battery cycle life and reduces resistance by optimizing charge reaction kinetics at elevated temperatures, outweighing the risks of elevated temperatures and enabling faster charging without compromising durability.
Implementation Method 1
heat the battery to a temperature between the lower threshold and the upper threshold
Implementation Method 2
cool the battery when a temperature of the battery exceeds a lower threshold
Data Source
AI summary
A vehicle includes a thermal system for a battery; and a controller for the thermal system. The controller may be configured to, during vehicle motion, cool the battery when a temperature of the battery exceeds a lower threshold and inhibit transfer of power with the battery when the temperature exceeds an upper threshold, and while coupled with a charge station, heat the battery to a temperature between the lower threshold and the upper threshold.