Asymmetric Cathode Loading for Stack-Type Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable lithium batteries with high nickel-based or cobalt-free positive electrode active materials face challenges in achieving high energy density while maintaining low charge/discharge efficiency, which affects cycle-life characteristics and capacity.
Innovation Solution
A stack-type rechargeable lithium battery design featuring a positive electrode with a first active material layer having a higher loading level than a second active material layer, where both layers consist of secondary and single particles respectively, optimized with specific chemical compositions and particle sizes to enhance cycle-life characteristics and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel-based or cobalt-free positive electrode active materials are used to increase energy density, then capacity is improved, but charge/discharge efficiency deteriorates due to cation mixing
Solution Approach 1:
The positive electrode active material is segmented into two distinct particle types: single particles with high charge/discharge efficiency and secondary particles (agglomerates of primary particles) with high capacity. This segmentation allows each particle type to contribute its strengths to the overall electrode performance, resolving the contradiction between capacity and efficiency
Solution Approach 2:
The invention creates a composite positive electrode active material comprising both single particles and secondary particles of high nickel-based or cobalt-free compounds. This composite structure combines the beneficial properties of single particles (high efficiency) with those of secondary particles (high capacity), achieving both improved capacity and maintained charge/discharge efficiency
2Quantity of substance
If positive electrode active materials with relatively low charge/discharge efficiency are used, then energy density can be increased, but cycle-life characteristics deteriorate significantly
Solution Approach 1:
The invention applies local quality by creating regions with different particle types within the positive electrode active material. Single particles provide high efficiency in certain regions while secondary particles provide high capacity in other regions, allowing the electrode to achieve both high energy density and improved cycle-life characteristics through spatial differentiation of material properties
3Ease of manufacture
If uniform loading levels are applied to both surfaces of the positive electrode, then manufacturing is simplified, but cell capacity and utilization rate are suboptimal
Solution Approach 1:
The invention introduces asymmetry in the loading levels of the positive electrode active material on the two surfaces of the current collector. By applying different loading levels (first loading level and second loading level) to opposite surfaces, the electrode design optimizes cell capacity and utilization rate, accepting increased manufacturing complexity as a trade-off for significantly improved productivity
Data Source
Figure 1
Figure 2
AI summary
A positive electrode for a stack-type rechargeable lithium battery includes a current collector, a first positive electrode active material layer on one surface of the current collector, and a second positive electrode active material layer on the other surface of the current collector, wherein a loading level of the first positive electrode active material layer is about 5% or more higher than a loading level of the second positive electrode active material layer, each of the first positive electrode active material layer and the second positive electrode active material layer includes a first positive electrode active material in the form of secondary particles and a second positive electrode active material in the form of single particles, an average particle diameter of secondary particles of the first positive electrode active material is larger than an average particle diameter of single particles of the second positive electrode active material.