Enhanced Lithium Battery Stability with Composite Electrode Materials
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Summary
Problems
Lithium secondary batteries face challenges with high irreversible capacity and structural instability due to excess lithium in positive electrode materials, leading to voltage sagging and degradation, particularly at high temperatures.
Innovation solutions
A positive electrode material comprising a combination of large and small lithium composite transition metal oxide particles, where the first material has a lithium-to-metal ratio of 1 to 1.5 and the second material has a crystallite size of 180 nm or more, enhancing structural stability and thermal performance.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If excess lithium-containing lithium transition metal oxide is used as positive electrode active material to achieve high capacity and high output, then capacity and output characteristics are improved, but irreversible capacity increases and oxygen is released causing structural collapse and voltage sagging
Why choose this principle:
The patent controls the lithium-to-transition metal ratio parameter within a specific range (1.05 ≤ Li/Me ≤ 1.30) to optimize the balance between capacity and structural stability. This parameter control prevents excessive lithium content that would cause oxygen release while maintaining high capacity characteristics.
Principle concept:
If excess lithium-containing lithium transition metal oxide is used as positive electrode active material to achieve high capacity and high output, then capacity and output characteristics are improved, but irreversible capacity increases and oxygen is released causing structural collapse and voltage sagging
Why choose this principle:
The patent uses composite lithium transition metal oxides containing multiple transition metals (Ni, Co, Mn) in specific ratios. This composite structure combines the high capacity benefits of excess lithium with the structural stability provided by manganese and cobalt, preventing oxygen release and structural collapse.
Application Domain
Data Source
AI summary:
A positive electrode material comprising a combination of large and small lithium composite transition metal oxide particles, where the first material has a lithium-to-metal ratio of 1 to 1.5 and the second material has a crystallite size of 180 nm or more, enhancing structural stability and thermal performance.
Abstract
A positive electrode material for a lithium secondary battery includes a first positive electrode active material and a second positive electrode active material, both of which are lithium composite transition metal oxides containing transition metals. The first positive electrode active material has a larger average particle size (D 50 ) than the second positive electrode active material, wherein a ratio (Li/Me) 1 of the mole number of lithium with respect to the total mole number of transition metals of the first positive electrode active material is more than 1 to 1.5 or less, and a ratio (Li/Me) 2 of the mole number of lithium (Li) with respect to the total mole number of transition metals of the second positive electrode active material is 0.9 to 1. The second positive electrode active material has a crystallite size of 180 nm or more.