Positive-Electrode Active Material for High-Capacity Batteries
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Solution Overview
Problem
Existing positive-electrode active materials for batteries face challenges in achieving high capacity and stability due to limitations in crystal structure, composition, and electrochemical reactions, leading to insufficient capacity and destabilization upon lithium deintercalation.
Innovation Solution
A positive-electrode active material with a composition formula LixMeyAzOαFβ, where Me includes elements like Mn, Co, Ni, and A includes B, Si, or P, with a crystal structure belonging to the Fm-3m space group, optimizing the ratios of x, y, z, α, and β to enhance capacity and stability by improving operating voltage, cycle characteristics, and Li intercalation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing positive-electrode active materials are used, then the battery can operate, but the capacity is insufficient and the structure destabilizes upon lithium deintercalation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the stoichiometric ratios in the composition formula LixMeyAzOαFβ, where x, y, z, α, and β are optimized within specific ranges. This changes the chemical composition parameters to achieve both high lithium content (x≥1.3) for capacity and appropriate metal element ratios (y) for structural stability, resolving the contradiction between capacity and stability
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Me = Mn, Co, Ni, Fe, Al, Cu, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ru, W) with lithium, oxygen, and fluorine in a specific composite formula. This composite structure allows the material to achieve both high capacity through multiple redox-active metals and enhanced stability through synergistic effects of different elements, particularly fluorine substitution which strengthens the crystal structure
2Quantity of substance
If lithium content is increased to improve capacity, then discharge capacity increases, but structure stability deteriorates upon lithium abstraction
Solution Approach 1:
The patent applies beforehand cushioning by incorporating fluorine substitution (Fβ where 0.1≤β≤1.2) into the crystal structure in advance. The fluorine atoms act as structural cushions that strengthen the crystal lattice and prevent collapse when lithium is abstracted during charging, allowing high lithium content (x≥1.3) to be maintained without compromising structural stability
Solution Approach 2:
The patent changes the compositional parameters by optimizing the ratio of lithium to other elements in the formula LixMeyAzOαFβ. By controlling x≥1.3 while maintaining appropriate y, z, α, and β values, the material achieves high lithium content for capacity while the balanced composition parameters ensure structural stability during lithium deintercalation
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 material achieves a high-capacity battery with improved cycle characteristics and stability, maintaining structure integrity even after significant lithium abstraction, resulting in higher discharge capacity and longer battery life.
Implementation Method 1
a battery including a positive-electrode active material... has an oxidation-reduction potential of approximately 3.3 V... The lithium-ion battery has a capacity of approximately 220 mAh/g or more
Implementation Method 2
Li intercalation efficiency... maintaining structure integrity even after significant lithium abstraction
Data Source
AI summary
A positive-electrode active material contains a compound represented by the following composition formula (1):LixMeyAzOαFβ (1)where Me denotes one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Cu, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ru, and W, A denotes one or more elements selected from the group consisting of B, Si, and P, and the following conditions: 1.3≤x≤2.1, 0.8≤y≤1.3, 0<z≤0.2, 1.8≤α≤2.9, and 0.1≤β≤1.2 are satisfied. A crystal structure of the compound belongs to a space group Fm-3m.