Low-Cobalt Cathode Composition for Battery Life and Resistance
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining resistance and life-span properties when using lithium metal oxide particles with low or no cobalt content, as they tend to have deteriorated performance due to high production costs and volume changes during charging and discharging.
Innovation Solution
A cathode for lithium secondary batteries is developed using lithium metal oxide particles with a cobalt content of less than 2 mol%, combined with specific conductive materials and a Raman spectrum intensity ratio (I D /I G) within a predetermined range, to enhance resistance and life-span properties while reducing cobalt content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium metal oxide particles with low or no cobalt content are used, then production cost is reduced, but resistance and life-span properties deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the lithium metal oxide particles by limiting cobalt content to 2 mol% or less while optimizing nickel content (60-80 mol%) and manganese content (10-40 mol%). This parameter adjustment reduces production cost while maintaining resistance and life-span properties through the optimized composition ratio.
Solution Approach 2:
The patent creates a composite cathode active material layer combining lithium metal oxide particles with specific conductive materials (carbon black, graphite, or carbon nanotubes) in controlled ratios. This composite structure compensates for the reduced cobalt content, maintaining electrical conductivity and structural stability, thereby preserving resistance and life-span properties while enabling lower cobalt usage.
2Ease of manufacture
If cobalt content in lithium metal oxide particles is reduced, then production cost decreases, but performance deteriorates due to volume changes during charging and discharging
Solution Approach 1:
The patent optimizes the compositional parameters of the lithium metal oxide particles by controlling the ratios of nickel (60-80 mol%), manganese (10-40 mol%), and cobalt (≤2 mol%). This parameter optimization reduces cobalt content for lower cost while the specific composition ratio mitigates volume changes during charging and discharging, maintaining performance stability.
Solution Approach 2:
The patent introduces conductive materials (carbon black, graphite, or carbon nanotubes) as intermediary substances in the cathode active material layer. These intermediaries compensate for the structural weaknesses caused by reduced cobalt content, stabilizing the particle structure during charging and discharging cycles, thereby preventing performance deterioration while enabling cost reduction.
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 effectively improves the resistance and life-span properties of lithium secondary batteries by adjusting the I D /I G value and using a blend of conductive materials, preventing deterioration and maintaining energy density, even with low or no cobalt content in the lithium metal oxide particles.
Implementation Method 1
The cathode active material layer includes a cathode active material and a conductive material
Implementation Method 2
I D is a maximum peak intensity in a range of 1,300 cm -1 in a Raman spectrum
Data Source
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AI summary
A cathode for a lithium secondary battery includes a cathode current collector, and a cathode active material layer formed on the cathode current collector. The cathode active material layer includes a cathode active material and a conductive material ID/IG is in a range from 0.5 to 1.25 in a Raman spectrum of the cathode active material layer. The cathode active material includes lithium metal oxide particles containing nickel and manganese and having a content of cobalt of less than 2 mol% among all elements except for lithium and oxygen.