Porous All-Solid Lithium Battery Electrodes for Lower Resistance
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Solution Overview
Problem
Existing all-solid lithium batteries with low-angle oriented positive electrode plates and specific solid electrolytes suffer from high battery resistance and poor high-rate performance during charge/discharge cycles.
Innovation Solution
The battery resistance and high-rate performance are improved by adjusting the porosity of the low-angle oriented positive electrode plates to 30 to 50% and filling 30% or more of the pores with a specific solid electrolyte, such as xLiOH-yLi2SO4 or Li a (OH) b F c Br, which has a melting point lower than the battery components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the porosity of the positive electrode plate is reduced to increase packing density, then the capacity increases, but the high-rate performance deteriorates due to insufficient electrolyte penetration
Solution Approach 1:
The patent utilizes a porous positive electrode plate with controlled porosity (10-50%) to enable sufficient electrolyte penetration while maintaining high packing density of active material. The porous structure allows electrolyte to reach deep into the electrode, ensuring good high-rate performance without sacrificing capacity.
Solution Approach 2:
The patent optimizes the porosity parameter of the positive electrode plate within a specific range (10-50%) to achieve the best balance between packing density and electrolyte penetration. This parameter optimization ensures both high capacity and good high-rate performance.
2Reliability
If a solid electrolyte with high melting point is used to ensure thermal stability, then the reliability improves, but the manufacturing process becomes more difficult due to limited permeation into pores
Solution Approach 1:
The patent utilizes the phase transition of the solid electrolyte from solid to liquid state during the heating process. The electrolyte is heated above its melting point to become liquid, enabling it to permeate into the pores of the positive electrode plate, and then cooled to solidify in place, achieving both good contact and thermal stability.
Solution Approach 2:
The patent performs preliminary heating of the solid electrolyte above its melting point before assembly, allowing it to flow and penetrate into the pores of the positive electrode plate in advance. This preliminary action ensures good interfacial contact and electrolyte distribution before the battery operates.
3Stability of the object's composition
If the orientation angle of primary grains is reduced to minimize expansion-contraction stress, then the interface stability improves, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent specifies a range for the orientation angle (0° to 30°) rather than a single value, making the manufacturing process more robust. This range-based specification balances interface stability requirements with manufacturing controllability, allowing reasonable variations while maintaining performance.
4Strength
If powder-dispersed positive electrodes with binder are used to ensure structural integrity, then the mechanical strength improves, but the capacity and charge/discharge efficiency decrease due to low packing density
Solution Approach 1:
The patent removes the binder component from the positive electrode structure, using only the active material particles themselves to form the electrode. This extraction of the non-active binder material eliminates the dead weight that reduces capacity and efficiency, while the particles are held together by van der Waals forces and the solid electrolyte.
Solution Approach 2:
The patent creates a composite structure where active material particles are combined with solid electrolyte, forming an integrated electrode-electrolyte composite. This composite structure provides both mechanical integrity and ionic conductivity without requiring organic binders, achieving high capacity and good charge/discharge efficiency.
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 configuration significantly enhances the production yield and improves the battery's high-rate performance and cycle characteristics by ensuring strong interfacial contact between the solid electrolyte and the electrode plates.
Implementation Method 1
pressing the negative electrode plate toward the oriented positive electrode plate, or the oriented positive electrode plate toward the negative electrode plate at 100 to 600°C to melt the solid electrolyte powder and permeate the melt into the pores in the oriented positive electrode plate
Implementation Method 2
melt the solid electrolyte powder and permeate the melt into the pores in the oriented positive electrode plate
Implementation Method 3
spontaneously or controllably cooling the oriented positive electrode plate, the molten electrolyte and the negative electrode plate to solidify the molten electrolyte
Data Source
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AI summary
Provided is an all-solid lithium battery that can significantly reduce battery resistance and remarkably improve high-rate performance during charge/discharge cycles, and can also greatly enhance the production yield of batteries. The all-solid lithium battery includes: a low-angle oriented positive electrode plate that is a lithium complex oxide sintered plate having a porosity of 10 to 50%; a negative electrode plate containing Ti and capable of intercalating and deintercalating lithium ions at 0.4 V or higher (vs. Li/Li+); and a solid electrolyte having a melting point lower than the melting point or pyrolytic temperature of the oriented positive electrode plate or the negative electrode plate, wherein at least 30% of pores in the oriented positive electrode plate is filled with the solid electrolyte in an observation of a cross-section perpendicular to a main face of the oriented positive electrode plate.