Li-Phosphate Sputtering Target for Stable Solid Electrolyte Deposition
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Solution Overview
Problem
The formation of Li-containing phosphoric-acid compound thin films for solid electrolytes in all-solid-state secondary batteries via sputtering methods is hindered by abnormal discharge and target cracking due to the generation of defects and impurity phases, such as Li4P2O7, which affects film-forming speed and stability.
Innovation Solution
A Li-containing phosphoric-acid compound sintered body with a high relative density and fine crystal grain diameter is achieved by using a raw material with an average particle diameter of 10 μm or less, sintered in a hot press furnace at 700 to 1000°C under vacuum or inert conditions, with a dew point of −30°C or lower, to minimize defects and impurity phases, resulting in a sputtering target that prevents abnormal discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sputtering targets with higher relative density (90% or more) are used, then manufacturing precision is improved, but abnormal discharge and target cracking occur during sputtering
Solution Approach 1:
The patent changes the particle size parameter of the raw material to 10 μm or less, which fundamentally alters the sintering behavior and microstructure development. This parameter change enables achieving high density (85% or more) while maintaining fine crystal grains (15 μm or less), thereby preventing abnormal discharge and target cracking during sputtering operations.
Solution Approach 2:
The patent performs preliminary particle size reduction of the raw material to 10 μm or less before sintering. This preliminary action ensures uniform packing and sintering behavior, leading to a sintered body with high density and fine crystal grains that are resistant to abnormal discharge and cracking during subsequent sputtering processes.
2Productivity
If film-forming speed is increased, then productivity is improved, but abnormal discharge occurs causing unstable operation
Solution Approach 1:
The patent changes the crystal grain size parameter to 15 μm or less through controlled sintering of fine particles. This parameter change creates a uniform fine-grained structure that prevents abnormal discharge even at high film-forming speeds, thereby maintaining both high productivity and stable operation.
3Manufacturing precision
If Li4P2O7 impurity phase is reduced, then manufacturing precision is improved, but requires stricter control of sintering conditions
Solution Approach 1:
The patent changes the raw material particle size to 10 μm or less, which fundamentally improves sintering uniformity and reduces Li4P2O7 impurity formation. This parameter change simplifies the sintering process control requirements while achieving high manufacturing precision in terms of impurity phase reduction.
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 enables stable and high-speed film formation of Li-containing phosphoric-acid compound thin films without abnormal discharge or target cracking, ensuring high film-forming speed and improved properties as a solid electrolyte.
Implementation Method 1
sintered in a hot press furnace at 700 to 1000°C under vacuum or inert conditions
Implementation Method 2
sintered in a hot press furnace at 700 to 1000°C under vacuum or inert conditions
Implementation Method 3
a sputtering method is preferably used in which a sputtering target made of substantially the same raw material as constitutes the film is sputtered
Data Source
AI summary
Provided is a Li-containing phosphoric-acid compound sintered body of both high relative density and very small crystal grain diameter with reduced incidence of defects (voids) such as air holes, the Li-containing phosphoric-acid compound sintered body causing a Li-containing phosphoric-acid compound thin film useful as a solid electrolyte for a secondary cell or the like to be stabilized without any incidence of target cracking or irregular electrical discharge, and offering high-speed film-forming capability. This Li-containing phosphoric-acid compound sintered body contains no defects measuring 50 μm or larger within a 1 mm2 cross-sectional region in the interior thereof, while having an average crystal grain diameter of no more than 15 μm and a relative density of at least 85%.