Lithium Complex Oxide Sintered Plate for Flexible Battery Electrodes
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Solution Overview
Problem
Miniaturized lithium secondary batteries for smart cards and wearable devices face challenges in achieving high capacity, energy density, bending resistance, and rapid charge characteristics due to limitations in the structure and porosity of conventional lithium complex oxide sintered plates, which lead to capacity retention issues and potential short circuits under bending stress.
Innovation Solution
A lithium complex oxide sintered plate with a specific structure featuring a layered rock-salt structure, porosity of 3-30%, mean pore diameter of 15 μm or less, open pore rate of 70% or more, and a thickness of 40-200 μm, with a controlled pore diameter distribution that disperses stress and enhances bonding strength, preventing grain boundary cracking and interface separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of lithium complex oxide sintered plate is increased to improve capacity and energy density, then the bending resistance deteriorates due to stress concentration and grain boundary cracking
Solution Approach 1:
The patent applies porous materials by controlling the sintered plate to have a porosity of 30-60% with a specific pore diameter distribution (D10: 0.5-5 μm, D50: 5-20 μm, D90: 20-50 μm). The porous structure reduces stress concentration during bending by providing stress relief pathways, while maintaining high capacity through increased surface area and ion transport channels. This resolves the contradiction between increasing thickness for capacity and maintaining bending resistance.
Solution Approach 2:
The patent changes physical parameters by precisely controlling porosity (30-60%), pore diameter distribution (D10: 0.5-5 μm, D50: 5-20 μm, D90: 20-50 μm), and thickness (50-200 μm) to achieve optimal performance. These parameter changes enable the sintered plate to simultaneously achieve high capacity, high bending resistance, and rapid charge characteristics by optimizing the balance between structural integrity and ion transport.
2Productivity
If the porosity is increased to improve ion transport and rapid charge characteristics, then the structural strength deteriorates leading to grain boundary cracking
Solution Approach 1:
The patent utilizes porous materials with controlled porosity (30-60%) and specific pore diameter distribution to enhance ion transport while maintaining structural strength. The interconnected porous network facilitates rapid lithium ion diffusion for fast charging, while the controlled pore size and distribution prevent excessive structural weakening, thus resolving the contradiction between rapid charge characteristics and structural strength.
Solution Approach 2:
The patent creates a composite structure within the sintered plate by combining densely sintered regions with porous regions. This composite architecture provides both mechanical strength from the dense framework and rapid ion transport pathways through the porous networks, effectively resolving the contradiction between structural strength and rapid charge characteristics.
3Quantity of substance
If the thickness is increased to improve capacity, then the uniformity of stress distribution deteriorates causing interface separation
Solution Approach 1:
The patent employs porous materials with controlled porosity (30-60%) and pore diameter distribution to improve stress distribution uniformity in thick sintered plates. The porous structure acts as a stress buffer that distributes mechanical loads more uniformly throughout the thickness, preventing stress concentration at interfaces. This enables the plate to maintain high capacity while achieving uniform stress distribution and preventing interface separation.
4Quantity of substance
If conventional sintering methods are used to produce thick plates, then the manufacturing cost increases and quality consistency deteriorates
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for porosity (30-60%), pore diameter distribution (D10: 0.5-5 μm, D50: 5-20 μm, D90: 20-50 μm), and thickness (50-200 μm) that can be consistently achieved through controlled sintering processes. These well-defined parameters enable manufacturers to produce thick plates with consistent quality and high bending resistance at scale, reducing manufacturing costs while maintaining performance.
Data Source
AI summary
Disclosed is a lithium complex oxide sintered plate for use in a positive electrode of a lithium secondary battery. The lithium complex oxide sintered plate has a structure in which a plurality of primary grains having a layered rock-salt structure are bonded, and has a porosity of 3 to 30%, a mean pore diameter of 15 μm or less, an open pore rate of 70% or more, a thickness of 40 to 200 μm, a primary grain diameter of 20 μm or less, the primary grain diameter being a mean diameter of the primary grains, and a pore diameter distribution in which the number of peaks is one and volume-based D10, D50 and D90 pore diameters satisfy expressions: D50/D10≥2.5, D90/D50≥2.5 and D90/D10≥8.0.