Positive Electrode Active Material for High-Voltage Cycle Stability
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Solution Overview
Problem
Developing a positive electrode active material for lithium-ion batteries with high specific capacity and good cycle performance, especially under high voltage conditions, is a pressing technical challenge due to the collapse of the crystal structure and subsequent capacity decay.
Innovation Solution
A positive electrode active material with a specific lithium metal oxide composition and crystal phase structure, represented by Formulas 1 and 2, is developed. This material includes a core of lithium metal oxide with a Cmca space group cubic lattice structure and a coating layer, which enhances structural stability and prevents capacity decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charge and discharge voltage is increased to increase battery capacity, then the specific capacity is improved, but the crystal structure collapses leading to rapid capacity decay and reduced cycle performance
Solution Approach 1:
The patent modifies the chemical composition parameters of the lithium metal oxide by incorporating multiple dopant elements (M1 and M2) at controlled concentrations. This changes the electronic and structural parameters of the material, enabling it to maintain structural integrity at high voltages while achieving high capacity. The specific composition ranges (0.01≤a≤0.1, 0.01≤b≤0.1, 0.01≤c≤0.1) are optimized to balance capacity and stability.
Solution Approach 2:
The patent creates a composite lithium metal oxide material by combining multiple elements (Li, Na, Co, M1, M2, O) in a specific composite structure. This composite approach allows the material to benefit from the synergistic effects of different elements: Li and Na provide high capacity, Co provides structural stability, M1 and M2 provide dopant effects that enhance both capacity and structural resilience against voltage-induced collapse.
2Quantity of substance
If the charge and discharge voltage is increased to increase battery capacity, then the specific capacity is improved, but the crystal structure collapses leading to rapid capacity decay
Solution Approach 1:
The patent optimizes compositional parameters by controlling the concentrations of dopant elements M1 and M2 within specific ranges (0.01≤a≤0.1, 0.01≤b≤0.1, 0.01≤c≤0.1). These parameter changes strengthen the crystal structure through dopant-induced lattice stabilization, allowing the material to withstand high voltage stress without structural collapse while maintaining high specific capacity.
Solution Approach 2:
The multi-element composite structure (Li1-n1-a1-b1Nan1Co1-a1M1b1M2a1O2) provides inherent structural stability through the synergistic interaction of different elements. The composite nature allows the crystal structure to resist voltage-induced collapse while enabling high lithium ion insertion/extraction, thus achieving both high specific capacity and structural stability.
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 positive electrode active material significantly improves the specific capacity and cycle performance of lithium-ion batteries, maintaining excellent performance even under high voltage conditions, and prevents structural collapse.
Implementation Method 1
in an X-ray diffraction spectrum, the lithium metal oxide is a Cmca space group of a cubic lattice structure
Data Source
AI summary
The present application provides a positive electrode active material and its use, where the positive electrode active material includes a lithium metal oxide as shown in Formula 1 or Formula 2; in an X-ray diffraction spectrum, the lithium metal oxide has a Cmca space group of a cubic lattice structure, and has a 002 peak with a 2θ of 17.9°-18.1°, and a 131 peak with a 2θ of 67.0°-67.5°. The positive electrode active material of the present application is beneficial to improving the cycle performance and specific capacity of lithium-ion batteries.