Porous Cathode Layers with Dual Electrolyte Films
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high energy density and rate capability while maintaining stability and durability, as high-density sintering of cathode active materials reduces ion conductivity and energy density.
Innovation Solution
The battery design incorporates cathode layers with a porous structure and a dual electrolyte film system, where the second electrolyte film is placed within the pores of the cathode layers, enhancing ion conductivity and energy density without compromising stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cathode active materials are sintered at high density to increase energy density, then capacity increases, but ion conductivity decreases
Solution Approach 1:
The cathode layer is designed with a porous structure containing multiple pores that penetrate through the layer. These pores provide pathways for ion transport, maintaining ion conductivity even when the cathode active material is densely sintered to increase energy density. The porous structure resolves the contradiction by providing both high material density for capacity and sufficient void space for ion conduction.
2Quantity of substance
If cathode layer thickness is increased to increase capacity, then energy density improves, but ion conductivity and rate capability deteriorate
Solution Approach 1:
The cathode layer is segmented into multiple regions connected by pores that extend through the entire thickness of the layer. This segmentation creates multiple parallel ion transport pathways, reducing the effective diffusion distance for ions even in thick cathode layers. As a result, capacity is maintained through increased thickness while ion conductivity is preserved through the distributed pore network.
3Quantity of substance
If cathode layer thickness is increased to increase capacity, then energy density improves, but rate capability deteriorates
Solution Approach 1:
The porous structure with pores penetrating through the cathode layer provides efficient ion transport channels that reduce resistance to ion flow. This enables fast charging and discharging rates even in thick cathode layers with high capacity, as ions can quickly reach active material sites through the pore network, thereby maintaining high rate capability.
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 increases energy density and rate capability by maintaining high ion conductivity across varying cathode layer thicknesses, from 30 μm to 50 μm, without significant capacity reduction.
Implementation Method 1
each of the cathode layers has a porous structure including a plurality of pores
Implementation Method 2
an electrolyte layer including a first electrolyte film surrounding external surfaces of the cathode layers, and a second electrolyte film disposed in the pores of the cathode layers
Data Source
AI summary
A secondary battery may include a plurality of cathode layers which have a porous structure including a plurality of pores, have a flat plate-shape, and are arranged to be spaced apart from each other in a direction. The secondary battery further includes an electrolyte layer including a first electrolyte film and a second electrolyte film, where the first electrolyte film surrounds external surfaces of the cathode layers, and the second electrolyte film is disposed in the pores of the cathode layers. The secondary battery further includes an anode layer surrounding the first electrolyte film.