All-Solid Lithium Battery Reducing Internal Resistance
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Solution Overview
Problem
Conventional all-solid lithium ion secondary batteries face challenges with high internal resistance and low capacity, particularly in the bulk type, which limits their performance and manufacturing efficiency.
Innovation Solution
Incorporating a compound containing lithium and boron into the positive electrode, negative electrode, and solid electrolyte layers, with specific mol % ranges of Li2CO3 and H3BO3, to enhance interface contact areas and lithium ion conductivity, thereby reducing internal resistance and improving capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a boron compound is added as a sintering aid to prevent delamination and reduce manufacturing cost, then manufacturing precision and ease of manufacture are improved, but the battery exhibits high internal resistance and low capacity
Solution Approach 1:
The patent changes the chemical composition parameters by adding specific amounts of lithium compound (4.38-13.34 mol% as Li2CO3) and boron compound (0.37-1.11 mol% as H3BO3) to the positive electrode active material, negative electrode active material, and solid electrolyte. This parameter optimization resolves the contradiction by achieving low internal resistance through controlled composition while maintaining manufacturing feasibility through a simplified one-step firing process that eliminates complex multi-step manufacturing procedures
Solution Approach 2:
The patent creates a composite material system by combining positive electrode active material, negative electrode active material, solid electrolyte, lithium compound, and boron compound into an integrated structure. This composite approach allows the boron compound to function as a sintering aid for manufacturing precision while the lithium compound compensates for capacity loss, simultaneously achieving low internal resistance and manufacturing efficiency
2Productivity
If the members are made into sheets and stacked then fired at the same time to enable mass production, then productivity is improved, but the internal resistance remains high and capacity is low
Solution Approach 1:
The patent modifies the chemical composition parameters of the sheet materials by incorporating specific ratios of lithium compound (4.38-13.34 mol% as Li2CO3) and boron compound (0.37-1.11 mol% as H3BO3) in the positive electrode, negative electrode, and solid electrolyte layers. This composition optimization enables the one-step firing process to produce sheets with low internal resistance and high capacity while maintaining the high productivity of mass production
Solution Approach 2:
The boron compound acts as an intermediary sintering aid that facilitates bonding between stacked sheets during firing, while the lithium compound serves as an intermediary that enhances lithium ion conductivity across interfaces. This intermediary mechanism allows mass production through sheet stacking and firing while achieving low internal resistance through improved interfacial contact and ion transport
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 addition of lithium and boron compounds at the interface and grain boundaries within the battery layers significantly reduces internal resistance and increases capacity, leading to a more efficient and reliable lithium ion secondary battery.
Implementation Method 1
enhance interface contact areas and lithium ion conductivity, thereby reducing internal resistance
Implementation Method 2
the members made into sheets and stacked and then fired at the same time
Data Source
AI summary
Provided is an all-solid lithium ion secondary battery including a sintered body including a solid electrolyte layer and a positive electrode layer and a negative electrode layer which are stacked alternately with the solid electrolyte layer interposed therebetween, wherein: the positive electrode layer, the negative electrode layer, and the solid electrolyte layer include a compound containing lithium and boron; and a content of lithium and boron contained in the compound to a total of a positive electrode active material included in the positive electrode layer, a negative electrode active material included in the negative electrode layer, and a solid electrolyte included in the solid electrolyte layer is respectively 4.38 mol % to 13.34 mol % in terms of Li2CO3 and 0.37 mol % to 1.11 mol % in terms of H3BO3.