Sintered Electrode Buffer Layer Neutralizes Acid
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Solution Overview
Problem
The challenge in producing oxide solid-state batteries is the chemical reaction between lithium containing composite oxide and lithium lanthanum zirconate at high temperatures, leading to a high resistance layer and reduced cathode capacity, which can be attributed to the generation of acid during the sintering process.
Innovation Solution
A method involving the use of a mixture of lithium lanthanum zirconate and a lithium salt with a lower melting point, combined with a hydroxide to neutralize the acid and suppress the deterioration of the cathode active material, allowing for a lower sintering temperature and improved charge and discharge capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature sintering is applied to join cathode active material to oxide solid electrolyte, then joining strength is improved, but chemical reaction occurs between materials forming high resistance layer
Solution Approach 1:
A buffer layer comprising lithium containing composite oxide and hydroxide is introduced between the cathode active material and the oxide solid electrolyte. This buffer layer acts as an intermediary that prevents direct chemical reaction between the cathode active material and the oxide solid electrolyte during sintering, while still allowing effective joining through sintering bonds to form at the interfaces.
Solution Approach 2:
The buffer layer is prepared in advance by mixing lithium containing composite oxide particles with hydroxide particles before the sintering process. This preliminary preparation ensures that the protective buffer layer is already in place before the high temperature sintering occurs, preventing the harmful chemical reactions that would otherwise take place between the cathode active material and the oxide solid electrolyte.
2Object-affected harmful factors
If sintering temperature is lowered to prevent chemical reaction, then harmful factors are reduced, but joining strength and cathode capacity deteriorate
Solution Approach 1:
The buffer layer serves as a protective intermediary that allows sintering to proceed at lower temperatures without causing harmful chemical reactions. The buffer layer composition is specifically designed to remain stable at the reduced sintering temperature while still enabling effective joining through sintering bonds.
Solution Approach 2:
The invention changes the sintering temperature parameter from high temperature (e.g., 900-1100°C) to a lower temperature range (e.g., 600-800°C). This parameter change is made possible by the presence of the buffer layer, which protects against chemical reactions that would otherwise occur at the higher temperatures needed for strong joining.
3Use of energy by moving object
If sintering temperature is lowered to improve energy efficiency, then energy consumption is reduced, but cathode capacity decreases due to material deterioration
Solution Approach 1:
The sintering temperature is reduced from conventional high temperatures to a lower range (600-800°C), which significantly reduces energy consumption. The buffer layer enables this temperature reduction while maintaining cathode capacity by preventing the chemical reactions and material deterioration that would otherwise occur.
Solution Approach 2:
The buffer layer protects the cathode active material from chemical reactions with the oxide solid electrolyte during low-temperature sintering. This protection maintains the structural integrity and electrochemical performance of the cathode active material, ensuring high cathode capacity is retained even at reduced sintering temperatures.
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
This approach effectively lowers the sintering temperature, neutralizes the acid generated during the reaction, and enhances the cathode capacity and overall battery performance by suppressing the deterioration of the cathode active material, resulting in higher charge and discharge capacities.
Implementation Method 1
heated at a temperature equal to or higher than the melting point of the lithium salt, to sinter the solid electrolyte mixture
Implementation Method 2
the generated acid and the cathode active material reacted with each other, to deteriorate the cathode active material... neutralizing the acid generated by the reaction of LLZ and the lithium salt with a hydroxide
Implementation Method 3
heated the laminate at a temperature equal to or higher than the melting point of the lithium salt, to sinter the solid electrolyte mixture and join the cathode active material to the solid electrolyte mixture
Data Source
AI summary
A sintered electrode having a large cathode capacity is obtained. A method for producing a sintered electrode which uses a lithium containing composite oxide as a cathode active material, and lithium lanthanum zirconate as an oxide solid electrolyte comprises: mixing at least the lithium containing composite oxide and a hydroxide, to obtain a cathode mixture; mixing at least the lithium lanthanum zirconate and a lithium salt that has a melting point lower than the lithium lanthanum zirconate, to obtain a solid electrolyte mixture; laminating the cathode mixture and the solid electrolyte mixture, to obtain a laminate; and heating the laminate, to sinter at least the solid electrolyte mixture.