Hexagonal Layered Lithium Metal Oxide Synthesis
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Solution Overview
Problem
Lithium metal oxides with cubic spinel-like structures in lithium and lithium-ion batteries undergo phase transformations, leading to poor electrochemical performance and hindered lithium ion diffusion, which affects battery cycling and energy density.
Innovation Solution
A method to produce lithium metal oxides with a substantially single-phase, hexagonal layered crystal structure by controlling the synthesis temperature and cooling rate, ensuring the absence of localized cubic spinel-like phases, using the formula Li x Ni a Co b Mn c O 2, where a, b, and c are within specific ranges, to maintain structural stability and enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium metal oxides are synthesized with cubic spinel-like structure, then synthesis is easier, but electrochemical performance deteriorates and lithium ion diffusion is hindered
Solution Approach 1:
The patent applies parameter changes by precisely controlling synthesis temperature (heating to 600-1000°C) and cooling rate (0.1-10°C/min) to transform the crystal structure from cubic spinel-like to hexagonal layered LiMO2, thereby improving electrochemical performance while maintaining synthesis feasibility
Solution Approach 2:
The patent utilizes phase transitions by controlling the transformation from cubic spinel-like phase to hexagonal layered phase through controlled cooling after high-temperature synthesis, eliminating harmful cubic phases and achieving superior electrochemical performance
2Reliability
If hexagonal layered structure is formed, then lithium ion diffusion improves, but synthesis requires precise temperature and cooling rate control
Solution Approach 1:
The patent optimizes synthesis parameters by heating to 600-1000°C and controlling cooling rate at 0.1-10°C/min, achieving hexagonal layered structure that enables superior lithium ion diffusion while managing process complexity through defined parameter ranges
Solution Approach 2:
The patent replaces complex mechanical control systems with a controlled cooling process that naturally achieves the desired hexagonal layered structure through thermodynamic principles, simplifying the synthesis process while maintaining high lithium ion diffusion performance
3Stability of the object's composition
If cubic spinel-like phases are present, then phase transformation occurs during cycling, but this leads to poor battery cycling performance
Solution Approach 1:
The patent controls phase transitions by eliminating cubic spinel-like phases through controlled cooling to form stable hexagonal layered structure, preventing harmful phase transformations during battery cycling and extending battery life
Solution Approach 2:
The patent applies preliminary anti-action by preventing the formation of harmful cubic spinel-like phases during synthesis through controlled cooling, thereby preemptively avoiding phase transformations that would degrade battery cycling performance
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 resulting lithium metal oxides exhibit improved electrochemical performance, consistent cycling, and higher energy density due to the absence of cubic spinel-like phases, which allows for better lithium ion diffusion and structural integrity during charge and discharge cycles.
Implementation Method 1
phase transformation between the two structures is possible and the layered structure is energetically favored only at high temperatures
Implementation Method 2
a method of preparing a compound having a substantially single phase, hexagonal layered crystal structure
Implementation Method 3
Layered LiCoO 2 also has an energetically favored tendency of changing into spinel LiCo 2 O 4 when 50% of the lithium ions are removed from the LiCoO 2 during electrochemical charging
Data Source
Figure 1~2
Figure 3a~4b
AI summary
The present invention relates to compounds having a hexagonal layered structure that is substantially free from cubic-spinel like phases, a process for preparing the same and the use thereof.