Battery Pack Cell Placement Using Impedance for Cold Discharge
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Solution Overview
Problem
Lithium-ion battery packs experience reduced low-temperature discharge capability due to polarization, leading to early cut-off voltage and inefficient energy use, with existing solutions increasing costs and complexity while compromising energy density and thermal stability.
Innovation Solution
The arrangement of first battery cells with high impedance and capacity at positions for enhanced heat exchange within the battery pack case, alongside second battery cells, to optimize heat distribution and reduce polarization, thereby increasing low-temperature discharge capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional thermistors are provided to improve low-temperature performance, then low-temperature discharge capability is improved, but cost increases and space is occupied reducing energy density
Solution Approach 1:
The patent extracts the thermal management function from separate thermistor components and integrates it into the battery cell structure itself. By making the battery cell case transparent to infrared radiation and incorporating specific heat-generating components, the cell structure performs both structural containment and thermal management functions, eliminating the need for additional thermistors and improving energy density while maintaining low-temperature performance.
Solution Approach 2:
The battery cell case is designed to serve multiple functions: mechanical containment, thermal management through infrared transparency, and heat generation enhancement. This multi-functionality eliminates the need for separate thermistor components, reducing cost and improving energy density while maintaining improved low-temperature discharge capability.
2Reliability
If low-temperature resistant batteries are arranged on the periphery to improve overall low-temperature performance, then low-temperature discharge capability is improved, but device complexity increases due to differentiated chemical system control
Solution Approach 1:
Instead of using different chemical systems for peripheral batteries, the patent applies local quality by making specific battery cells (particularly peripheral ones) transparent to infrared radiation and equipping them with enhanced heat generation capabilities. This allows uniform chemical composition throughout the pack while providing localized thermal enhancement where most needed, simplifying BMS control.
3Reliability
If low-temperature resistant batteries are used to improve low-temperature performance, then low-temperature discharge capability is improved, but thermal stability deteriorates bringing about collision safety issues
Solution Approach 1:
The patent introduces an intermediary mechanism - infrared-transparent case material and controlled heat generation - that allows thermal energy to be retained and distributed within the battery pack without requiring chemically modified batteries. This mediator approach maintains the stability of standard battery chemistry while achieving improved low-temperature performance through thermal 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 configuration enhances the battery pack's low-temperature discharge performance by increasing heat generation and temperature rise, overcoming the 'battery pack cask effect' and improving overall capacity and energy retention rates.
Implementation Method 1
the first battery cells are arranged at positions where heat exchange with surroundings is more likely to occur in the battery pack case
Implementation Method 2
overcoming the 'battery pack cask effect' and increasing the low-temperature discharge capability
Data Source
AI summary
The present application provides a battery pack and a power consuming device. The battery pack includes a battery pack case; and first battery cells and second battery cells that are accommodated in the battery pack case, wherein compared with the second battery cells, the first battery cells are arranged at positions where heat exchange with surroundings is more likely to occur in the battery pack case. It is assumed that the first battery cells each have a capacity C1 and a direct-current impedance R1, wherein X1=C1*R1, the second battery cells each have a capacity C2 and a direct-current impedance R2, wherein X2=C2*R2, and X1 and X2 satisfy 1.1≤X1/X2≤2.0.