Non-Aqueous Battery Cathode Composition for Longer Cycle Life
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries require improvement in charge-discharge cycle characteristics for on-board and power storage applications, as existing technologies like those described in Patent Literatures 1 and 2 still fall short in achieving optimal cycle characteristics.
Innovation Solution
A non-aqueous electrolyte secondary battery design incorporating a positive electrode with a mixture layer containing a first lithium-transition metal composite oxide (LixNi1-y-zCoyMzO2) and a second lithium-transition metal composite oxide (LiaNi2-a-bMebO2), along with a non-aqueous electrolyte that includes a sulfonylimide salt, which enhances the battery's cycle characteristics by protecting the surface of the active materials and inhibiting side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active materials (Patent Literatures 1 and 2) are used, then battery structure is simple, but charge-discharge cycle characteristics are insufficient
Solution Approach 1:
The patent applies composite materials by combining a first lithium-transition metal composite oxide (LixNi1-y-zCoyMzO2) and a second lithium-transition metal composite oxide (LiaNi2-a-bMebO2) in the positive electrode mixture layer. This composite structure improves charge-discharge cycle characteristics while managing structural complexity through systematic material design.
Solution Approach 2:
The patent implements local quality by creating a core-shell structure where the first lithium-transition metal composite oxide forms the core and the second lithium-transition metal composite oxide forms the surface layer. This local differentiation optimizes both bulk capacity and surface stability, resolving the contradiction between reliability and structural complexity.
2Use of energy by moving object
If higher capacity is pursued, then energy storage increases, but cycle stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios and stoichiometric parameters (x, y, z, a, b) of the lithium-transition metal composite oxides. This systematic parameter optimization enables simultaneous achievement of high capacity and cycle stability by adjusting material composition within specific ranges.
Solution Approach 2:
The second lithium-transition metal composite oxide acts as an intermediary protective layer on the surface of the first composite oxide. This intermediate structure mediates between the high-capacity core material and the electrolyte environment, enabling both high energy storage and long cycle life by preventing direct degradation reactions.
3Reliability
If sulfonylimide salt is added to non-aqueous electrolyte, then cycle characteristics improve, but electrolyte composition complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration and type of sulfonylimide salt in the non-aqueous electrolyte. This controlled addition improves cycle characteristics while managing electrolyte complexity through systematic composition design and concentration optimization.
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 proposed battery configuration significantly improves charge-discharge cycle characteristics, achieving both higher capacity and better cycle stability through the combination of specific composite oxides and sulfonylimide salts, leading to remarkable improvements in battery performance.
Implementation Method 1
a non-aqueous electrolyte, which includes a sulfonylimide salt
Implementation Method 2
inhibiting side reactions
Data Source
AI summary
This non-aqueous electrolyte secondary battery, which is one example of an embodiment, comprises: a positive electrode that has a positive electrode mixture layer; a negative electrode; and a non-aqueous electrolyte. The positive electrode mixture layer contains a first lithium-and-transition-metal composite oxide represented by general formula LixNi1-y-zCoyMzO2 (in the formula, 0.8≤x≤1.2, 0≤y≤0.2, 0<z≤0.5, and M is at least one metal element excluding Li, Ni, and Co), and a second lithium-and-transition-metal composite oxide represented by general formula LiaNi2-a-bMebO2 (in the formula, 0<a≤0.5, 0≤b≤0.5, and Me is at least one metal element excluding Li and Ni). The non-aqueous electrolyte contains a sulfonyl imide salt.