Battery Pack Cell Layout for Low-Temperature Energy 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, leading to poor endurance.
Innovation Solution
A battery pack design that divides its internal space into temperature regions, with specific battery cells arranged in each region to optimize temperature distribution, using lithium iron phosphate positive electrodes with a low-temperature additive containing compounds with conjugated carbonyl groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple lithium-ion secondary battery cells are connected in series or parallel to improve overall discharging capacity, then the battery pack can meet higher energy requirements, but the energy retention rate deteriorates significantly in low-temperature environments
Solution Approach 1:
The patent applies local quality by adding different amounts of low-temperature additive to the positive electrode active substance in different battery cells based on their position in the battery pack. Specifically, battery cells in different thermal environments (first, second, and third battery cells) receive different concentrations of low-temperature additive (first amount, second amount, and third amount respectively), allowing each cell to be optimized for its specific operating conditions. This resolves the contradiction by enabling high discharging capacity through multiple cells while maintaining energy retention rate through localized material composition adjustments.
2Ease of manufacture
If the battery pack is designed with uniform battery cell arrangement, then the structure is simple and easy to manufacture, but the temperature distribution becomes uneven leading to poor low-temperature performance
Solution Approach 1:
The patent implements local quality by creating a non-uniform arrangement of battery cells with different low-temperature additive compositions according to their positional temperature characteristics. The battery pack is divided into regions (first, second, third regions) with different thermal properties, and each region contains battery cells with specifically formulated positive electrodes. This maintains relatively simple overall structure while improving low-temperature endurance through localized material optimization.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition parameters of the positive electrode active substance - specifically the content of low-temperature additive - based on the thermal environment of different battery cell positions. By changing the additive concentration parameter (first amount, second amount, third amount) in different regions, the patent optimizes low-temperature performance without fundamentally altering the battery pack structure.
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 the battery pack's energy retention rate and discharging power at low temperatures by reducing discharging capacity differences between cells and improving overall energy retention.
Implementation Method 1
the low-temperature additive being selected from one or more of compounds containing at least two carbonyl groups that are respectively or jointly conjugated with a double bond, an unsaturated monocyclic ring or unsaturated fused ring
Data Source
AI summary
Provided is a battery pack. The battery pack includes a first battery cell, a second battery cell, and a third battery cell. A positive electrode active substance of each battery cell is composed of lithium iron phosphate and a low-temperature additive. The low-temperature additive is selected from compounds containing at least two carbonyl groups, which are conjugated with an unsaturated structure or an atom having lone-pair electrons connected with the carbonyl groups. At a temperature lower than or equal to 10° C., a ratio of a discharging capacity of a single cell of the second battery cell to a discharging capacity of a single cell of the first battery cell ranges from 1.003 to 1.12, and a ratio of a discharging capacity of a single cell of the third battery cell to a discharging capacity of a single cell of the second battery cell ranges from 1.005 to 1.15.