Battery Pack Thermal Zoning to Prevent Low-Temperature Cask Effect
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Solution Overview
Problem
Lithium-ion secondary battery packs used in electric vehicles experience a significant reduction in energy retention rate at low temperatures, leading to decreased endurance mileage during winter use.
Innovation Solution
A battery pack design that divides its interior space into regions with different temperature change rates, placing high-performance battery cells in areas with larger temperature changes and standard cells in areas with smaller changes, ensuring energy exertion is balanced across regions to avoid the 'cask effect' and maintain high energy retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery cells are uniformly distributed in the battery pack, then the structure is simple and easy to manufacture, but the energy retention rate at low temperature is significantly reduced due to the cask effect
Solution Approach 1:
The patent applies local quality by differentiating battery cell performance characteristics across different spatial regions within the battery pack. Specifically, it places high-performance battery cells (with better low-temperature characteristics) in the first region and standard-performance battery cells in the second region, allowing each location to contribute optimally to overall pack performance based on its thermal environment
Solution Approach 2:
The patent segments the battery pack into multiple regions (first region and second region) with different thermal characteristics and places different types of battery cells in each region. This segmentation allows the system to address the cask effect by ensuring that no single weak cell limits the overall pack performance, thereby improving energy retention at low temperatures
2Reliability
If high-performance battery cells are placed in regions with larger temperature changes, then low-temperature energy retention is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements local quality by matching battery cell performance characteristics to the thermal environment of specific regions. High-performance cells are strategically placed in the first region experiencing larger temperature changes, while standard cells are placed in the second region with more stable temperatures, optimizing overall pack performance
Solution Approach 2:
The patent changes the performance parameters of battery cells by selecting cells with different discharge capacity ratios (E1′/E1 between 0.95-1.67 and E2′/E2 between 0.65-0.95) to match the thermal characteristics of different regions, thereby achieving consistent energy exertion across the entire pack at low temperatures
Data Source
AI summary
The present application provides a battery pack and a power consuming device powered by the battery pack. The battery pack includes a battery pack cavity and a plurality of battery cells received in the battery pack cavity. An interior space of the battery pack cavity can be divided into a first region with a temperature change rate of K1 and a second region with a temperature change rate of K2, where 0.066≤K1≤0.131 and 0.034≤K2≤0.066, K1 and K2 being expressed in ° C./min. The plurality of battery cells include at least one first battery cell arranged in the first region, and at least one second battery cell arranged in the second region. The battery pack of the present application can reduce or avoid the cask effect at low temperature and improve the energy retention rate at low temperature.