Lithium Battery Design for High-Temperature Stability
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Summary
Problems
Lithium secondary batteries face challenges with high-temperature stability and life characteristics due to rapid phase transitions and chemical instability in nickel-based transition metal oxides, leading to battery swelling and reduced capacity, especially when exposed to high voltages and elevated temperatures.
Innovation solutions
A lithium secondary battery design incorporating a positive electrode with a core-shell structure of lithium-metal oxides, including nickel, manganese, and cobalt, and an electrolyte containing a difluorophosphite compound to stabilize the electrode structure and reduce gas production during high-temperature storage.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a lithium nickel-based transition metal oxide with high nickel content is used to increase capacity, then the energy density is improved, but excessive gas is produced during storage and cycles causing battery swelling and high-temperature stability deteriorates
Why choose this principle:
The positive electrode active material is segmented into two distinct components: a first lithium-metal oxide providing high capacity and a second lithium-metal oxide providing structural stability. This segmentation allows each component to fulfill its specific function, resolving the contradiction between high energy density and high-temperature stability.
Principle concept:
If a lithium nickel-based transition metal oxide with high nickel content is used to increase capacity, then the energy density is improved, but excessive gas is produced during storage and cycles causing battery swelling and high-temperature stability deteriorates
Why choose this principle:
The patent creates a composite positive electrode active material by combining two different lithium-metal oxides with complementary properties. The first lithium-metal oxide contributes high capacity while the second lithium-metal oxide suppresses gas production and maintains stability at high temperatures, achieving both high energy density and reliability.
Application Domain
Data Source
AI summary:
A lithium secondary battery design incorporating a positive electrode with a core-shell structure of lithium-metal oxides, including nickel, manganese, and cobalt, and an electrolyte containing a difluorophosphite compound to stabilize the electrode structure and reduce gas production during high-temperature storage.
Abstract
Provided is a lithium secondary battery, and the lithium secondary battery of the present invention includes: a positive electrode including a first lithium-metal oxide including secondary particles formed by aggregating primary particles having a particle diameter of 2 μm or less and a second lithium-metal oxide including nickel and at least one or more metals selected from the group consisting of manganese (Mn) and cobalt (Co) and including particles having a primary particle diameter of 2 μm or more; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte, wherein the electrolyte includes a lithium salt, a nonaqueous organic solvent, and a difluorophosphite compound containing at least one or more difluorophosphite groups.