High-Nickel Cathode Strain Control for Longer-Life Lithium Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving improved capacity characteristics and lifespan characteristics, particularly due to the trade-off between high nickel content for high energy density and the resulting decreased long-term stability and increased side reactions.
Innovation Solution
The lithium secondary battery incorporates lithium-nickel-based metal oxide particles with a controlled crystallite strain of 0.2 to 0.4, calculated using the Williamson-Hall method, which includes a balanced composition of nickel, manganese, and optionally cobalt, to enhance electrochemical activation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the nickel content in lithium-nickel-based metal oxide is increased to implement high energy density, then the energy density is improved, but the long-term stability and lifespan characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite strain (ε) within the range of 0.2 to 0.4, as calculated by the Williamson-Hall method using XRD analysis. This parameter optimization allows the cathode to maintain high nickel content for energy density while the controlled strain prevents structural deterioration, thereby improving both energy density and long-term stability simultaneously
Solution Approach 2:
The patent uses composite materials by incorporating multiple elements (Ni, Mn, Co, and other transition metals) in the lithium-nickel-based metal oxide with general formula Li_x Ni_{1-y} M_y O_{2+z}. This composite approach allows high nickel content for energy density while other elements provide structural stability, resolving the contradiction between energy density and long-term stability
2Use of energy by moving object
If the nickel content is increased to achieve high energy density, then the energy density is improved, but side reactions increase
Solution Approach 1:
The patent controls the crystallite strain parameter (ε) within 0.2 to 0.4, which modifies the structural properties of the high-nickel cathode material. This parameter control reduces structural deterioration and suppresses side reactions between the cathode and electrolyte, allowing high nickel content to be used without excessive side reactions while maintaining high energy density
3Reliability
If the crystallite strain is controlled to improve capacity retention and lifespan, then the stability is improved, but the energy density may be compromised
Solution Approach 1:
The patent optimizes the crystallite strain parameter (ε) within the specific range of 0.2 to 0.4, as determined by Williamson-Hall analysis of XRD patterns. This precise parameter control achieves the optimal balance where capacity retention and lifespan are improved while maintaining high energy density through appropriate nickel content in the cathode material
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 approach improves the capacity retention and lifespan of the lithium secondary battery by maintaining high energy density while reducing structural deterioration and side reactions.
Implementation Method 1
The lithium secondary battery may store an electric energy by a difference in chemical potential when lithium ions are intercalated and deintercalated between the cathode and the anode
Implementation Method 2
peaks of (101) plane, (102) plane, (104) plane, (105) plane and (107) plane of the lithium-nickel-based metal oxide particles measured through XRD analysis
Implementation Method 3
crystallite strain (ε), which is calculated by applying the Williamson-Hall method defined by Equation 1 below to peaks of (101) plane, (102) plane, (104) plane, (105) plane and (107) plane
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
A lithium secondary battery according to the embodiments of the present disclosure includes: a cathode which includes a cathode active material layer including a cathode active material containing lithium-nickel-based metal oxide particles; and an anode disposed to face the cathode, wherein the lithium-nickel-based metal oxide particles have a crystallite strain (ε) of 0.2 to 0.4, which is calculated by applying the Williamson-Hall method defined a predetermined equation to peaks of (101) plane, (102) plane, (104) plane, (105) plane and (107) plane of the lithium-nickel-based metal oxide particles measured through XRD analysis on the cathode active material layer. Accordingly, capacity characteristics and lifespan characteristics of the lithium secondary battery are improved.