Sprayed Lithium Cobalt Oxide Targets for DC Sputtering
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Solution Overview
Problem
Lithium cobalt oxide sputtering targets with high resistivity are not suitable for direct current (DC) sputtering, requiring additional conductive materials and limiting their application in achieving high deposition rates and stable sputtering over a wide range of pressures and powers.
Innovation Solution
A sputtering target with a top coat comprising lithium cobalt oxide (LiCoOx) having an X-Ray diffraction pattern with a peak at 44°±0.2° 2-theta, which enables DC sputterability without the need for conductive elements, achieved through thermal spraying of lithium cobalt oxide powder onto a backing substrate, resulting in a Fd-3m cubic spinel phase that reduces resistivity with increasing power, allowing high deposition rates and stable sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium cobalt oxide with high resistivity is used as sputtering target, then the target material provides high capacity and good ion conductivity, but the target cannot be sputtered in direct current mode due to insufficient electrical conductivity
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen content (x value) in lithium cobalt oxide (LiCoOx) to be less than 2.0, which fundamentally alters the electrical conductivity properties of the material. This compositional parameter change enables the material to achieve sufficient conductivity for DC sputtering while maintaining its electrochemical performance for battery applications.
Solution Approach 2:
The patent creates a composite structure by combining lithium cobalt oxide with specific crystal phase characteristics (indicated by the XRD peak at 44°±0.2° 2-theta) that provide enhanced electrical conductivity. This composite approach maintains the beneficial electrochemical properties while adding the necessary conductive characteristics for DC sputtering operation.
2Manufacturing precision
If conventional sputtering targets are used to achieve thick cathode layers (3-10 μm), then the deposition process requires additional conductive materials, but this increases device complexity and limits deposition efficiency
Solution Approach 1:
The patent extracts and eliminates the need for additional conductive materials (such as carbon black or metal powders) from the target composition. By achieving sufficient conductivity through the lithium cobalt oxide composition control itself, the patent removes these extraneous components, simplifying the target structure while maintaining the ability to deposit thick cathode layers with precise thickness control.
Solution Approach 2:
The patent changes the compositional parameters of lithium cobalt oxide (specifically the oxygen stoichiometry) to inherently provide the necessary electrical conductivity, eliminating the need for composite conductive additives. This parameter optimization allows for simpler target design while achieving the same or better deposition performance.
3Productivity
If high power is applied to increase deposition rate, then the sputtering efficiency improves, but arcing and heterogeneous bands occur in conventional targets
Solution Approach 1:
The patent changes the material parameters of lithium cobalt oxide to achieve a balance that allows high power operation without arcing. The controlled oxygen deficiency and specific crystal phase structure enable the material to dissipate energy more uniformly, permitting higher deposition rates while maintaining plasma stability and avoiding heterogeneous band formation.
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 target allows for efficient DC sputtering with high deposition rates per unit power density, maintaining stability across various pressures and powers, and produces a homogeneous sputtered layer without the issues of arcing and heterogeneous bands, enhancing the performance and uptime of the sputtering process.
Implementation Method 1
Deposition of such a LiCoO2 cathode layer may be achieved by sputtering
Implementation Method 2
providing a backing substrate, projecting, preferably thermal spraying, said powder in a molten form onto said backing substrate
Implementation Method 3
wherein the lithium cobalt oxide has an X-Ray diffraction pattern with a peak P2 at 44°±0,2° 2-theta, wherein the X-Ray diffraction pattern is measured with an X-Ray diffractometer with CuKα1 radiation
Data Source
AI summary
A sputtering target comprising a top coat including a composition of lithium cobalt oxide LiyCozOx. x is smaller than or equal to y+z, and the lithium cobalt oxide has an X-Ray diffraction pattern with a peak P2 at 44°±0.2° 2-theta. The X-Ray diffraction pattern is measured with an X-Ray diffractometer with CuKα1 radiation.