Mixed-Chemistry Battery Module Using Cell Heat Sharing at Low Temperature
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Solution Overview
Problem
Lithium-ion secondary battery modules or packs experience rapid capacity degradation and poor power performance in low-temperature environments, particularly in high-latitude or high-altitude conditions, due to increased internal resistance and reduced lithium ion mobility.
Innovation Solution
A battery module comprising cells of different chemical systems, where one type of cell has a higher alternating current impedance and discharge resistance growth rate than the other, allowing the first type of cell to generate more heat and transfer it to the second type, maintaining an ideal temperature range for improved capacity and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large-capacity battery modules or packs are used to increase total energy released, then energy capacity is improved, but in low-temperature environments capacity retention and power performance deteriorate rapidly
Solution Approach 1:
The battery module is segmented into different types of battery cells (first type and second type) with different chemical systems. Each type has different impedance characteristics, allowing the module to benefit from both high capacity and low-temperature performance. The first type cells provide higher capacity while the second type cells with lower impedance maintain power performance at low temperatures.
Solution Approach 2:
Different regions of the battery module have different cell types with locally optimized properties. The first type cells are positioned to provide energy capacity while the second type cells are positioned to provide power performance and heat generation at low temperatures, creating local quality differences that resolve the contradiction.
2Power
If cells with higher impedance are used to generate more heat at low temperature, then power performance is improved, but discharge resistance growth rate increases
Solution Approach 1:
The higher impedance of the first type cells, which would normally be considered harmful due to heat generation and resistance growth, is converted into a benefit by positioning these cells to provide the necessary heat at low temperatures. The impedance-related heat generation is transformed from a harmful factor into a useful heating mechanism that maintains operational temperature.
Solution Approach 2:
The battery module uses a composite structure with two different types of battery cells having different chemical systems and impedance characteristics. This composite approach allows the module to combine the high capacity of one cell type with the low-temperature power performance of another cell type, resolving the contradiction between power performance and resistance growth.
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
The solution enhances capacity retention and power performance of the battery module at low temperatures by ensuring the second type of cell operates within an optimal temperature range, thereby mitigating the effects of low-temperature degradation.
Implementation Method 1
the alternating current impedance of the first type of cell is greater than that of the second type of cell, so that the first type of cell releases more heat than the second type of cell does
Implementation Method 2
The first type of cell transfers heat to the second type of cell, adjusting an actual temperature of the second type of cell to be in an ideal temperature range
Data Source
AI summary
A battery module, a battery pack, and an electric apparatus are provided. In some embodiments, the battery module includes a first type of cell and a second type of cell that are cells of different chemical systems, where the first type of cell includes n first cells, the second type of cell includes m second cells, n and m each are selected from an integer greater than 1, at least one of the first cells and at least one of the second cells are electrically connected in series, and the first cell and the second cell satisfy at least the following relationships: 0.08≤ΔRB/ΔRA≤3.50, and 0.10 mΩ/100 cycles≤ΔRA≤0.40 mΩ/100 cycles, where ΔRA is a discharge resistance growth rate of the first cell, and ΔRB is a discharge resistance growth rate of the second cell; and IMPB<IMPA, where IMPA is an alternating current impedance of the first cell, and IMPB is an alternating current impedance of the second cell.