Dual-Layer Positive Electrode Coating for Solid-State Battery Resistance
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Solution Overview
Problem
All-solid-state batteries face issues such as irreversibility due to interfacial side reactions between the solid electrolyte and the electrode, uneven electrode charge distribution, and high resistance, which degrade battery capacity and efficiency.
Innovation Solution
A positive electrode comprising a first and second positive electrode layer with specific coating layer contents and thickness ratios, where the first coating layer is less than 1% by weight and the second is 1% or more, using lithium metal oxides and lithium oxide coating layers to reduce resistance and suppress side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coating layer is applied to the positive electrode active material, then interfacial side reactions between the solid electrolyte and electrode active material are reduced, but resistance increases due to the coating layer acting as a resistor
Solution Approach 1:
The patent applies different coating layer contents to different regions of the positive electrode. The first positive electrode layer (in contact with solid electrolyte) has a coating layer content of 0.1-5 wt%, while the second positive electrode layer (not in contact with solid electrolyte) has a coating layer content of 0.1-1 wt%. This local differentiation allows the region facing the solid electrolyte to have sufficient protective coating to suppress side reactions, while the inner region has minimal coating to reduce resistance and improve charge-discharge performance.
2Quantity of substance
If the loading within the electrode is increased to improve capacity, then energy density is improved, but resistance deviation increases due to the protective layer acting as a resistor
Solution Approach 1:
The patent creates a spatial gradient in coating layer content across the electrode structure. By positioning the higher coating content (0.1-5 wt%) in the first positive electrode layer that interfaces with the solid electrolyte and the lower coating content (0.1-1 wt%) in the second positive electrode layer, the design enables high loading capacity while controlling resistance deviation. The differentiated coating strategy ensures that the protective function is concentrated where needed at the interface, while the bulk material maintains low resistance for efficient charge transport.
3Duration of action of stationary object
If a thick coating layer is applied to suppress side reactions, then battery life is improved, but charge and discharge performance deteriorates due to increased resistance
Solution Approach 1:
The patent implements a differentiated coating strategy where the first positive electrode layer contains 0.1-5 wt% coating layer to suppress interfacial side reactions and extend battery life, while the second positive electrode layer contains only 0.1-1 wt% coating layer to minimize resistance and maintain high charge-discharge performance. This local quality differentiation allows simultaneous optimization of both battery longevity and power performance.
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 solution enhances battery performance by uniformly involving positive electrode active material in charging and discharging, improving initial capacity, efficiency, and lifetime characteristics.
Implementation Method 1
interfacial side reactions between the solid electrolyte and the electrode
Implementation Method 2
the protective layer itself is a resistor, resulting in resistance deviation as the loading within the electrode increases
Data Source
Figure 1
AI summary
The present invention relates to a positive electrode for a secondary battery and a secondary battery comprising the same, and more particularly to a positive electrode for a secondary battery comprising a first positive electrode layer and a second positive electrode layer.