LLZ Solid-State Lithium-Ion Cell Sintering for Low Resistance and Capacity
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving both high capacity and low internal resistance due to excessive crystal growth of electrolyte particles during sintering, which reduces capacity and increases internal resistance when the heating temperature is adjusted.
Innovation Solution
Incorporating a sintering aid with atoms like B, P, or Si in the manufacturing process to suppress excessive crystal growth of LLZ-based solid electrolyte in the porous body while promoting crystal growth in the separator, allowing for integral formation of the porous body and separator at temperatures between 700° and 1050°, thereby maintaining high capacity and low internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating temperature during sintering is increased to promote crystal growth in the separator, then the internal resistance decreases, but excessive crystal growth occurs in the porous body reducing capacity
Solution Approach 1:
The patent applies local quality by adding different sintering aid compositions to different regions: the separator contains sintering aids (B, P, or Si atoms) that promote crystal growth and reduce internal resistance, while the porous body uses different sintering aids or no sintering aids to suppress excessive crystal growth and maintain capacity. This spatial differentiation of material properties resolves the contradiction between reducing internal resistance and maintaining capacity.
Solution Approach 2:
The patent changes the chemical composition parameter by introducing sintering aids containing specific atoms (B, P, or Si) at controlled concentrations (0.01-0.50 atomic ratio relative to LLZ). By adjusting the type and amount of sintering aids in different regions, the patent optimizes crystal growth behavior to simultaneously achieve low internal resistance in the separator and high capacity in the porous body.
2Reliability
If the heating temperature is increased to ensure sufficient bonding of electrolyte particles, then the internal resistance decreases, but the pore capacity of the porous electrolyte material is reduced
Solution Approach 1:
The patent implements local quality by differentiating the sintering aid composition between the separator and porous body. The separator receives sintering aids that promote dense crystal growth for low internal resistance, while the porous body uses different sintering conditions to maintain pore structure integrity and capacity, resolving the contradiction between bonding strength and pore preservation.
Solution Approach 2:
The sintering aids act as intermediaries that mediate the sintering process. By introducing B, P, or Si atoms as sintering aids, the patent enables sufficient bonding of electrolyte particles at lower temperatures while preserving pore structure, thus reducing internal resistance without sacrificing pore capacity.
3Quantity of substance
If the heating temperature is decreased to preserve pore capacity, then the capacity increases, but the electrolyte particles are insufficiently bonded increasing internal resistance
Solution Approach 1:
Sintering aids containing B, P, or Si atoms serve as intermediaries that facilitate bonding between electrolyte particles at lower heating temperatures. This enables sufficient bonding and low internal resistance while preserving pore capacity, resolving the contradiction between capacity and internal resistance at reduced sintering temperatures.
Solution Approach 2:
The patent changes the chemical composition by introducing sintering aids that lower the effective sintering temperature. This allows the system to achieve sufficient bonding and low internal resistance at temperatures that preserve pore capacity, effectively decoupling the trade-off between bonding quality and pore preservation.
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 increases the capacity of the lithium-ion secondary battery while reducing internal resistance by controlling crystal growth, ensuring efficient lithium-ion conductivity and storage capacity.
Implementation Method 1
Incorporating a sintering aid with atoms like B, P, or Si in the manufacturing process to suppress excessive crystal growth of LLZ-based solid electrolyte in the porous body while promoting crystal growth in the separator, allowing for integral formation of the porous body and separator at temperatures between 700° and 1050°
Implementation Method 2
suppress excessive crystal growth of LLZ-based solid electrolyte in the porous body while promoting crystal growth in the separator
Data Source
AI summary
A lithium-ion secondary battery includes: a single cell that includes a first electrode, a separator stacked on the first electrode, and a second electrode stacked on the separator. The first electrode includes a porous body that includes at least one LLZ-based solid electrolyte of a lithium lanthanum zirconate or the lithium lanthanum zirconate doped with an atom other than a Li atom, a La atom, and a Zr atom, and has a pore, and an active material held in the pore. The separator has a relative density of 80% or more, and includes the at least one LLZ-based solid electrolyte of the lithium lanthanum zirconate or the lithium lanthanum zirconate doped with the atom other than the Li atom, the La atom, and the Zr atom, and at least one of a B atom, a P atom, or a Si atom.