Battery Pack Thermal Segmentation for Low-Temperature Energy Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The energy retention rate of lithium-ion secondary battery packs used in electric vehicles significantly decreases at low temperatures, leading to reduced endurance mileage.
Innovation Solution
A battery pack design that divides its interior space into regions with different temperature change rates, using battery cells with varying low-temperature performance to ensure consistent energy exertion across regions, thereby avoiding the 'cold creep' effect and improving overall energy retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery cells are uniformly distributed in the battery pack cavity, then the structure is simple and easy to manufacture, but the energy retention rate at low temperature deteriorates due to temperature gradients causing the cask effect
Solution Approach 1:
The battery pack cavity is divided into a first region and a second region based on temperature change rates. The first region (with higher temperature change rate K1) contains first battery cells with better low-temperature performance, while the second region (with lower temperature change rate K2) contains second battery cells. This spatial segmentation resolves the contradiction by allowing differentiated cell placement to improve low-temperature energy retention without requiring complex overall structural changes.
Solution Approach 2:
Different types of battery cells are placed in different regions of the battery pack according to local temperature characteristics. First battery cells with superior low-temperature performance are positioned in the first region experiencing higher temperature change rates, while second battery cells are positioned in the second region. This local quality differentiation enables the battery pack to maintain high energy retention rates across varying temperature conditions while preserving a relatively simple overall structure.
2Reliability
If battery cells with different low-temperature performance are used in different regions, then the energy exertion consistency at low temperature is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The battery pack is segmented into two regions with different temperature characteristics, allowing the use of different battery cell types in each region. This segmentation enables energy exertion consistency across the pack by matching cell performance to local thermal conditions, while the segmentation itself follows a straightforward spatial division that does not significantly complicate manufacturing processes.
Solution Approach 2:
Battery cells with appropriate low-temperature performance characteristics are selectively placed in specific regions based on their thermal environment. First battery cells with better low-temperature performance are positioned in the first region, while second battery cells are positioned in the second region. This local quality matching improves energy consistency without requiring complex manufacturing procedures, as it involves primarily strategic cell placement rather than complex assembly operations.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present application provides a battery pack and a power consuming device. The battery pack comprises a battery pack cavity and a plurality of battery cells received in the battery pack cavity, wherein 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<KI<0.131 and 0.034<K2<0.066, K1 and K2 being expressed in °C/min; the plurality of battery cells comprises: at least one first battery cell arranged in the first region; and at least one second battery cell arranged in the second region; and the full discharge energies of the first battery cell and the second battery cell when standing at 25°C are E1 and E2 respectively and the full discharge energies of the first battery cell and the second battery cell when standing at -20°C are E1' and E2' respectively, where 1<E1/E2≤1.5, and 0.95≤E1'/E2'≤1.67, E1, E2, E1', and E2' being expressed in Wh. The battery pack of the present application can avoid the cask effect at low temperature and improve the energy retention rate at low temperature.