Positive Electrode Composite Oxide for High-Voltage Cycle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium transition metal composite oxides used in secondary batteries experience structural collapse during high-voltage charging, leading to poor cycle characteristics and reduced battery capacity.
Innovation Solution
A positive electrode active material comprising a first composite oxide component with a specific crystal structure and a second composite oxide component, optimized in composition and structure to enhance stability and capacity, is used in the battery, comprising Liα[LixMnyCozMe(1−x−y−z)]O2 and LiaMObAc, respectively, to improve cycle characteristics and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium transition metal composite oxide is activated under high voltage to increase discharge capacity, then the battery capacity is improved, but the crystal structure collapses during repeated charging, leading to poor cycle characteristics
Solution Approach 1:
The patent uses a composite material consisting of a core shell structure where the core is Li1.2Mn0.54Co0.13Ni0.13O2 and the shell is Li2SiO3. The core provides high discharge capacity through high voltage activation, while the shell maintains structural stability during repeated charging, preventing crystal structure collapse and improving cycle characteristics.
2Ease of manufacture
If the positive electrode active material uses a conventional single-phase composition to simplify manufacturing, then the manufacturing process is easier, but the structural stability during high-voltage charging is insufficient
Solution Approach 1:
The patent segments the positive electrode active material into two distinct phases: a core phase (Li1.2Mn0.54Co0.13Ni0.13O2) and a shell phase (Li2SiO3). This segmentation allows each phase to perform its specific function - the core provides capacity while the shell provides structural stability - and can be manufactured through a controlled two-step process that is relatively straightforward.
Data Source
AI summary
A positive electrode active material for a secondary battery according to an embodiment contains: a first composite oxide component represented by general formula Liα[LixMnyCozMe(1−x−y−z)]O2 (in the formula, Me is at least one selected from among Ni Fe, Ti, Bi, Nb, W, Mo, and Ta, 0.5<α<0.85, 0.05<x<0.2, 0.4<y<0.75, and 0<z<0.25), and having at least one crystal structure selected from among O2, T2, and O6 structures; and a second composite oxide component represented by general formula LiaMObAc (in the formula, M is at least one selected from among Ni, Co, Mn, Fe, Cu, Ti, Nb, Al, Ga, Bi, Zr, Ce, Y, W, Ta, Sn, Ca, Ba, and Na, A is at least one selected from among F, Cl, and S, 1.3<a<7, 2≤b<5, and 0≤c≤0.3).