Positive Electrode Particle Structure for Stable Battery Capacity
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in maintaining capacity and cycle performance due to charge and discharge cycles, requiring improvements in positive electrode active materials for enhanced safety and reliability.
Innovation Solution
A positive electrode active material particle comprising a first region with a layered rock-salt crystal structure and a second region with a rock-salt crystal structure, where the second region contains magnesium and fluorine, is developed to stabilize the crystal structure and inhibit capacity reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material is used in lithium-ion secondary batteries, then capacity and charge-discharge characteristics can be improved, but capacity decreases due to charge and discharge cycles
Solution Approach 1:
The positive electrode active material uses a composite structure with lithium, magnesium, and fluorine components. The specific composite material composition (Li-Mg-F system) creates a stable crystal structure that maintains capacity during charge-discharge cycles, resolving the contradiction between achieving high capacity and maintaining cycle performance reliability.
Solution Approach 2:
The invention optimizes specific parameter ratios of lithium, magnesium, and fluorine in the active material. By controlling the compositional parameters within specific ranges, the material achieves both high capacity and improved cycle stability, preventing capacity degradation over repeated cycles.
2Reliability
If the crystal structure is stabilized to inhibit capacity reduction, then cycle performance improves, but material composition complexity increases
Solution Approach 1:
The invention introduces magnesium and fluorine at specific locations within the crystal structure to stabilize particular regions. This localized modification approach stabilizes the crystal structure for improved cycle performance while minimizing overall material composition complexity, as the stabilizing elements are incorporated in specific ratios rather than uniformly throughout.
Data Source
AI summary
Positive electrode active material particles that inhibit a decrease in capacity due to charge and discharge cycles are provided. A high-capacity secondary battery, a secondary battery with excellent charge and discharge characteristics, or a highly-safe or highly-reliable secondary battery is provided. A novel material, active material particles, and a storage device are provided. The positive electrode active material particle includes a first region and a second region in contact with the outside of the first region. The first region contains lithium, oxygen, and an element M that is one or more elements selected from cobalt, manganese, and nickel. The second region contains the element M, oxygen, magnesium, and fluorine. The atomic ratio of lithium to the element M (Li/M) measured by X-ray photoelectron spectroscopy is 0.5 or more and 0.85 or less. The atomic ratio of magnesium to the element M (Mg/M) is 0.2 or more and 0.5 or less.