Nickel-Rich Cathode Material with Stable Li-O Layer Spacing
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Solution Overview
Problem
Lithium secondary batteries with high nickel content face rapid degradation in structural integrity and lifetime characteristics, especially at high temperatures, due to exothermic reactions and structural deterioration, which existing doping or coating techniques fail to adequately address.
Innovation Solution
A lithium secondary battery design featuring a nickel-rich positive electrode active material with a layered structure and a nickel content of 85% or more, where the lithium-oxygen interlayer spacing change is minimized to 3% or less in a specific state-of-charge range, utilizing a lithium composite transition metal oxide with a coating layer and measured using high-resolution powder diffraction data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a Ni-rich NCM-based lithium oxide with high nickel content (80 atm% or more) is used as positive electrode active material, then capacity implementation is improved, but structural stability and chemical stability decrease leading to rapid degradation in lifetime characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling the nickel content to be 80 atm% or more of total transition metals, and controlling the atomic ratios of cobalt and manganese within specific ranges (0.05≤b≤0.20 and 0.05≤c≤0.20). This optimization of compositional parameters achieves high capacity while suppressing cation mixing and maintaining structural stability during charging-discharging cycles.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (nickel, cobalt, manganese) in a specific ratio to create Li(Ni a Co b Mn c )O 2. This composite approach leverages nickel for high capacity, cobalt for structural stability, and manganese for chemical stability, achieving a balance that resolves the contradiction between capacity and lifetime characteristics.
2Quantity of substance
If a positive electrode active material with high nickel content (80 atm% or more) is used, then capacity characteristics are improved, but structural integrity degrades rapidly under high-temperature conditions
Solution Approach 1:
The patent controls the atomic ratios of transition metals within specific ranges to optimize structural stability at high temperatures. By setting 0.05≤b≤0.20 for cobalt and 0.05≤c≤0.20 for manganese, the material maintains structural integrity during thermal stress while preserving high capacity characteristics.
Solution Approach 2:
The patent accepts controlled surface degradation as a trade-off, focusing on maintaining bulk structural integrity. The material is designed to tolerate surface changes during charging-discharging cycles while preserving core structural stability, effectively managing the limited lifetime under high-temperature conditions.
3Quantity of substance
If a positive electrode active material with high nickel content (80 atm% or more) is used, then capacity implementation is improved, but cation mixing and irreversible phase transformation are accelerated under high-temperature conditions
Solution Approach 1:
The patent optimizes the atomic ratios of transition metals to suppress cation mixing and phase transformation at high temperatures. By controlling the nickel content at 80 atm% or more while limiting cobalt and manganese to specific ranges, the material achieves high capacity implementation while resisting high-temperature degradation mechanisms.
Solution Approach 2:
The patent converts the potential harm of high nickel content (which accelerates cation mixing and phase transformation) into a benefit by carefully balancing it with cobalt and manganese. The controlled presence of these elements suppresses the harmful effects while preserving the high capacity benefits of nickel-rich composition.
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 battery exhibits excellent capacity and high-temperature lifetime characteristics by maintaining structural stability and enabling smooth lithium ion migration, preventing rapid degradation.
Implementation Method 1
enabling smooth lithium ion migration, preventing rapid degradation
Implementation Method 2
secondary batteries which allow charging and discharging and thus have semi-permanent characteristics and allow for repeated use
Data Source
Figure 1
AI summary
Provided is a lithium secondary battery which includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode includes a lithium composite transition metal oxide powder having a layered structure and a nickel content accounting for 85 atm% or more of total transition metals, and wherein the lithium composite transition metal oxide powder undergoes a 3% or less change in lithium-oxygen (Li-O) interlayer spacing in a state-of-charge (SOC) range of 58% to 72%.