Battery Cell Segmented Jellyroll Design for Thermal Runaway Prevention
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Solution Overview
Problem
Ternary lithium-ion batteries used in new energy vehicles face safety issues such as spontaneous combustion, thermal runaway, and rapid capacity attenuation due to unstable nickel-cobalt-aluminium and nickel-cobalt-manganese materials, especially at high temperatures, leading to potential fires and explosions.
Innovation Solution
A cell design incorporating a jellyroll A with a first positive-electrode sheet and a jellyroll B with a ternary positive-electrode sheet, using specific active materials like lithium iron phosphate and lithium nickel cobalt manganate, along with controlled thicknesses and coatings to manage heat and ion migration, reducing the number of ternary sheets and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ternary positive-electrode sheets (nickel-cobalt-aluminium or nickel-cobalt-manganese) are used to achieve high energy density, then the battery capacity and energy storage are improved, but the structural stability deteriorates at high temperature leading to safety issues
Solution Approach 1:
The positive electrode is divided into two types of sheets: first positive-electrode sheets with stable materials (lithium iron phosphate or lithium manganese iron phosphate) and second positive-electrode sheets with ternary materials (nickel-cobalt-aluminium or nickel-cobalt-manganese). This segmentation allows the battery to achieve high energy density from the ternary sheets while the stable sheets provide structural support and safety at high temperatures, preventing spontaneous combustion and thermal runaway.
2Use of energy by moving object
If the number of ternary positive-electrode sheets is increased to improve energy density, then the battery capacity is improved, but the risk of thermal runaway and explosion increases
Solution Approach 1:
Different regions of the battery are assigned different electrode configurations. The first positive-electrode sheets with stable materials are strategically placed to provide local safety zones that prevent thermal runaway, while the second positive-electrode sheets with high-capacity ternary materials are placed in regions optimized for energy density. This local quality differentiation allows the battery to achieve high overall capacity while maintaining safety through distributed stable regions.
3Use of energy by moving object
If high pH value materials are used to improve battery performance, then the energy density is improved, but the cell monomer becomes unstable and may bloat
Solution Approach 1:
The positive electrode uses a composite structure combining first positive-electrode sheets with stable materials (lithium iron phosphate or lithium manganese iron phosphate having low pH values) and second positive-electrode sheets with ternary materials. This composite material approach allows the stable low-pH materials to counterbalance the high-pH ternary materials, preventing cell monomer bloat while maintaining the high energy density benefits of the ternary components.
Data Source
Figure 1~3
Figure 4
AI summary
A cell includes a jellyroll A and a jellyroll B. The jellyroll A is formed by laminating a first positive-electrode sheet, a separator, a negative-electrode sheet, and another separator sequentially; the jellyroll B comprises a first portion of laminates and a second portion of laminates laminated on the first portion of laminates. The first portion of laminates is formed by laminating a first positive-electrode sheet, a separator, a negative-electrode sheet, and another separator sequentially; the second portion of laminates is formed by laminating a ternary positive- electrode sheet, a separator, a negative-electrode sheet, and another separator sequentially.