Yttria-Stabilized Zirconia Substrate for Solid-State Battery
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Solution Overview
Problem
Conventional lithium-ion and lithium polymer batteries face safety issues due to flammable liquid electrolytes and have limited energy density due to a high ratio of inactive materials, while solid-state batteries with lithium phosphorous oxynitride electrolytes offer improved safety and energy density but require suitable substrates that can withstand high annealing temperatures and have matching thermal expansion coefficients.
Innovation Solution
The use of yttria-stabilized zirconia (YSZ) substrates, which can withstand annealing temperatures between 700° C and 800° C and have a near-zero coefficient of thermal expansion, allowing for the growth of thicker lithium cobalt oxide cathodes without cracking, thereby enhancing the energy density of solid-state batteries to approximately 1030 Wh/L.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium-ion and lithium polymer batteries use liquid electrolytes, then the batteries can operate with standard components, but the liquid electrolyte becomes flammable and presents safety issues
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid by using lithium phosphorous oxynitride (LiPON) solid-state electrolyte. This parameter change eliminates the flammability issue inherent in liquid electrolytes while maintaining ionic conductivity necessary for battery operation.
Solution Approach 2:
The patent employs a composite structure combining solid-state LiPON electrolyte with lithium cobalt oxide cathode and graphite anode. This composite material approach creates a safe battery system that leverages the non-flammable properties of solid electrolytes while maintaining electrochemical performance.
2Quantity of substance
If conventional lithium-ion and lithium polymer batteries use high ratios of inactive materials (polymer separator, liquid electrolyte), then the battery structure is simple, but the energy density is limited to approximately 500-550 Wh/L
Solution Approach 1:
The patent extracts and eliminates the inactive polymer separator component by using a solid-state LiPON electrolyte that simultaneously functions as both electrolyte and separator. This removal of redundant inactive materials increases the ratio of active to inactive materials, thereby increasing energy density.
Solution Approach 2:
The solid-state LiPON electrolyte performs multiple functions: it serves as both the ionic conductor (electrolyte) and the physical barrier between electrodes (separator). This multi-functionality eliminates the need for separate inactive components, increasing energy density.
3Quantity of substance
If solid-state batteries use lithium anode with theoretical specific capacity of 3800 mAh/g, then the energy density increases to approximately 1000 Wh/L, but the battery requires substrates that can withstand high annealing temperatures
Solution Approach 1:
The patent changes the substrate material parameter to yttria-stabilized zirconia (YSZ), which has the capability to withstand high annealing temperatures (700-800°C) required for processing lithium cobalt oxide cathodes. This parameter change enables the use of high-capacity lithium anode and thick cathodes without substrate degradation.
4Manufacturing precision
If solid-state batteries anneal lithium cobalt oxide cathodes at high temperatures (700-800°C), then the cathode crystallization and performance are optimized, but substrates with mismatched thermal expansion coefficients cause cracking
Solution Approach 1:
The patent changes the substrate material parameter to YSZ, which has a near-zero coefficient of thermal expansion. This parameter change matches the thermal expansion characteristics of lithium cobalt oxide cathode, preventing cracking during high-temperature annealing while enabling optimal cathode crystallization.
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 YSZ substrate enables solid-state batteries to achieve improved energy density and safety by allowing optimal annealing of lithium cobalt oxide cathodes, reducing the risk of flammability and increasing the battery's capacity without material degradation.
Implementation Method 1
YSZ substrates, which can withstand annealing temperatures between 700° C and 800° C
Implementation Method 2
have a near-zero coefficient of thermal expansion, allowing for the growth of thicker lithium cobalt oxide cathodes without cracking
Data Source
AI summary
Disclosed are solid-state batteries having improved energy density and methods of manufacturing the solid-state batteries having improved energy density. In some embodiments, the solid-state battery may include a substrate of yttria-stabilized zirconia, a cathode current collector formed on the substrate, an anode current collector formed on the substrate, a cathode of lithium cobalt oxide in electrical contact with the cathode current collector, an anode of lithium in electrical contact with the anode current collector, and a solid-state electrolyte of lithium phosphorous oxynitride formed between the cathode and the anode.