LiCoO2 Oriented Sintered Plate Grain Boundary Reduction
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Solution Overview
Problem
LiCoO2 oriented sintered plates with the (104) plane parallel to the surface often have a polycrystalline structure with significant grain boundaries in the thickness direction, leading to poor lithium ion conductivity and battery performance.
Innovation Solution
A method involving a green sheet with Co3O4 particles, fired at 900 to 1450°C to align the (h00) plane parallel to the surface, with optional Mg-containing compound attachment before or after lithium introduction to reduce grain boundaries and enhance crystal alignment, resulting in a LiCoO2 oriented sintered plate with improved lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a LiCoO2 oriented sintered plate with (104) plane parallel to surface is produced by conventional firing, then the crystal orientation is achieved, but significant grain boundaries form in the thickness direction resulting in poor lithium ion conductivity
Solution Approach 1:
The invention changes the chemical composition parameter by adding a specific amount of Al2O3 (0.1-5 wt%) to the green sheet formulation. This compositional modification suppresses abnormal grain growth and reduces grain boundary formation in the thickness direction during firing, while maintaining the desired (104) plane orientation parallel to the surface, thus resolving the contradiction between crystal orientation and lithium ion conductivity
Solution Approach 2:
The invention creates a composite structure by incorporating Al2O3 particles into the LiCoO2 matrix. The Al2O3 acts as a grain growth inhibitor that prevents excessive grain boundary formation in the thickness direction while allowing the LiCoO2 crystals to maintain their preferred (104) orientation parallel to the surface, thereby improving lithium ion conductivity without sacrificing crystal orientation
2Manufacturing precision
If the green sheet thickness is reduced to 100 μm or less, then the manufacturing precision of crystal orientation is improved, but the handling and processing difficulty increases
Solution Approach 1:
The invention applies local quality enhancement by adding Al2O3 specifically to the green sheet formulation, which improves the mechanical strength and handling properties of the thin sheet (100 μm or less) without affecting the overall thin profile. This localized compositional modification enables the thin sheet to be handled and processed more easily while maintaining the precise crystal orientation achieved through the thin geometry
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 method significantly reduces grain boundaries in the plate thickness direction, enhancing lithium ion conductivity and battery performance, particularly rate characteristics, when used as a positive electrode active material in lithium secondary batteries.
Implementation Method 1
firing the green sheet at a temperature of 900 to 1450° C. to obtain a Co3O4 oriented sintered plate
Implementation Method 2
a (h00) plane is aligned in parallel with a sheet surface
Implementation Method 3
firing the Co3O4 oriented sintered plate in the presence of a lithium source to introduce lithium
Implementation Method 4
attaching a Mg-containing compound to the Co3O4 oriented sintered plate before the step (c) or to the lithium cobaltate oriented sintered plate after the step (c) and firing the lithium cobaltate oriented sintered plate having the Mg-containing compound
Data Source
AI summary
Provided is a method for manufacturing a lithium cobaltate oriented sintered plate, comprising (a) providing a green sheet comprising Co3O4 particles, (b) firing the green sheet to form a Co3O4 oriented sintered plate, and (c) firing the sintered plate in the presence of a lithium source to introduce lithium and thereby form the lithium cobaltate oriented sintered plate composed of LiCoO2, the method further comprising (d1) attaching a Mg-containing compound to the Co3O4 oriented sintered plate before the step (c) or (d2) attaching the Mg-containing compound to the lithium cobaltate oriented sintered plate after the step (c) to fire the sintered plate. According to the present invention, a lithium cobaltate oriented sintered plate can be manufactured in which grain boundaries in the plate thickness direction are significantly reduced and with which enhanced battery performance can be achieved when used as a positive electrode active material in lithium secondary batteries.