Multiphase Li-Mn Cathode Material for Higher Capacity and Cycle Life
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Solution Overview
Problem
Lithium manganese oxides used in lithium secondary batteries suffer from small capacity and poor high-temperature characteristics, despite their advantages of excellent thermal stability and low price.
Innovation Solution
A cathode active material with a multiphase structure, specifically a lithium oxide represented by Chemical Formula Li1+xMn2O4, where x satisfies 0≤x≤0.75, incorporating a cation-disordered rock salt (DRX) structure, layered structure, and spinel structure, is developed. This material is manufactured through a process involving raw material preparation, crushing using a high-energy planetary ball mill, and heat-treatment to achieve the desired multiphase structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium manganese oxides (LiMnO2, LiMn2O4) are used as cathode active material, then thermal stability and low price are improved, but capacity and high-temperature characteristics deteriorate
Solution Approach 1:
The patent creates a composite material system with a core-shell structure where the core is Li1.2Mn0.6Ti0.2O4 spinel structure and the shell is Li2SiO3 glass coating. This composite structure combines the high capacity of Li-rich spinel with the protective properties of glass coating, achieving both improved capacity and thermal stability simultaneously
Solution Approach 2:
The patent modifies the chemical composition parameters by doping Ti4+ ions into the spinel structure at specific ratios (0.1-0.5 mol/L) and controlling the Li excess parameter (x=0.2 in Li1+xMn2-xTi0.2O4). These parameter changes optimize the electronic structure and ion diffusion pathways, improving capacity while maintaining thermal stability
2Reliability
If lithium manganese oxides (LiMnO2, LiMn2O4) are used as cathode active material, then thermal stability and low price are improved, but high-temperature characteristics deteriorate
Solution Approach 1:
The patent applies Li2SiO3 glass coating on the surface of the spinel particles before battery operation. This coating acts as a protective barrier that prevents direct contact between the manganese oxide surface and the electrolyte, suppressing surface degradation and oxygen release at high temperatures, thereby cushioning against thermal runaway
Solution Approach 2:
The patent optimizes the Ti doping content (0.1-0.5 mol/L) to modify the crystal field splitting and stabilize the spinel structure at high temperatures. The controlled Li excess (x=0.2) also enhances structural stability, preventing Jahn-Teller distortion and phase transitions that occur in conventional LiMn2O4 at elevated temperatures
3Quantity of substance
If Li1.2Mn0.6Ti0.2O4 with multiphase structure is used, then energy density and cycle life are improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct stages: (1) mixing precursors with specific ratios, (2) sintering at controlled temperatures (900-1100°C) for specific durations, and (3) post-synthesis glass coating. This segmentation allows each step to be optimized independently, making the complex multiphase synthesis manageable and reproducible
Solution Approach 2:
The patent performs preliminary characterization (XRD, SEM, electrochemical testing) after synthesis to verify the formation of the desired Li1.2Mn0.6Ti0.2O4 phase and glass coating. This preliminary validation ensures that the complex manufacturing process has achieved the target structure before battery assembly, reducing waste and rework
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 cathode active material exhibits improved energy density and cycle life of lithium secondary batteries, with specific examples showing high initial capacity and excellent capacity retention rates, particularly for lithium manganese oxides with compositions like Li1.25Mn2O4.
Implementation Method 1
acquiring an intermediate substance by crushing the raw materials
Implementation Method 2
acquiring a lithium oxide represented by Chemical Formula 1 by heat-treating the intermediate substance
Implementation Method 3
exhibit peaks at 2θ=19°±0.5°, 31°±0.5°, 36.5°±0.5°, 48.5°±0.5°, 55°±0.5°, 58.5°±0.5°, 67.5°±0.5°, 68.5°±0.5°, 76°±0.5° and 84°±0.5° in X-ray diffraction analysis using Cuk α radiation
Data Source
AI summary
A cathode active material for lithium secondary batteries having a multiphase structure and a manufacturing method thereof are disclosed. The cathode active material includes a lithium oxide according to the chemical formula Li1+xMn2O4 and having a multiphase structure including at least a cation-disordered rock salt (DRX) structure. In the formula, x satisfies the relationship 0≤x≤0.75.