Battery Pack Electrode Zoning for Low-Temperature Discharge Retention
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Solution Overview
Problem
Lithium-ion battery packs experience a significant reduction in energy retention rate when used in low-temperature environments, such as winter, due to varying discharge capabilities and heat insulation effects across different positions within the pack.
Innovation Solution
The battery pack is designed with multiple regions within the internal space, each with a distinct temperature gradient, where battery cells with different discharge voltage plateaus are strategically placed to maintain optimal performance. These cells include lithium iron phosphate and supplementary active substances like Li3V2(PO4)3, which help in prolonging the discharging process and improving power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-ion secondary battery cells are connected in series or parallel to increase discharge capacity, then the overall discharge capacity of the battery pack is improved, but the energy retention rate under low temperature is significantly reduced
Solution Approach 1:
The patent divides the battery pack into multiple regions based on temperature distribution, with each region containing battery cells having different positive electrode active substances optimized for local temperature conditions. This local optimization ensures that cells in colder regions maintain better discharge performance, thereby improving overall energy retention rate under low temperature while preserving total discharge capacity
Solution Approach 2:
The patent changes the chemical composition parameter of the positive electrode active substance across different regions. By using lithium iron phosphate in warmer regions and supplementary active substances like lithium nickel cobalt manganate in colder regions, the discharge voltage plateau characteristics are optimized for each temperature zone, resolving the contradiction between capacity and low-temperature retention
2Reliability
If battery cells with different discharge voltage plateaus are distributed in different regions, then the energy retention rate under low temperature is improved, but the device complexity increases
Solution Approach 1:
The patent segments the battery pack into distinct temperature-based regions and assigns specific battery cell types to each segment. This segmentation allows for optimized performance in each region while maintaining a systematic and organized structure that manages complexity through clear zonation rather than random distribution
Solution Approach 2:
The patent systematically varies the positive electrode active substance composition parameter across regions based on temperature gradients. This parameter change strategy creates a predictable pattern for battery cell distribution, making the complex multi-component system manageable through standardized regional configurations
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 ensures a higher overall energy retention rate and improved power performance of the battery pack under low-temperature conditions by optimizing the discharge capacity proportions and voltage plateaus across different regions, thereby enhancing the pack's endurance in cold environments.
Implementation Method 1
a positive electrode of each k-th battery cell includes a positive electrode active substance, the positive electrode active substance including the following substances: lithium iron phosphate and/or lithium nickel cobalt manganate having a first discharge voltage plateau, and one or more types of supplementary active substances having a second discharge voltage plateau
Implementation Method 2
lithium iron phosphate and/or lithium nickel cobalt manganate having a first discharge voltage plateau, and one or more types of supplementary active substances having a second discharge voltage plateau
Implementation Method 3
based on determined temperature distribution in an entire internal space of the battery pack box during use under low temperature
Implementation Method 4
temperature distribution in an entire internal space of the battery pack box during use under low temperature
Data Source
AI summary
A battery pack includes a battery pack box with an internal space including a first region to an n-th region, each provided with a battery cell. A positive electrode active substance in a positive electrode of each k-th battery cell includes lithium iron phosphate and/or lithium nickel cobalt manganate having a first discharge voltage plateau and one or more types of supplementary active substances having a second discharge voltage plateau. For the first battery cell to the n-th battery cell, in any case where a sum of a discharge capacity corresponding to the first discharge voltage plateau and a discharge capacity corresponding to the second discharge voltage plateau is 100%, a discharge capacity proportion corresponding to the second discharge voltage plateau of the k-th battery cell is greater than a discharge capacity proportion corresponding to the second discharge voltage plateau of the (k−1)-th battery cell.