Nickel Cathode Active Material with Crack-Resistant Crystallite Control
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Solution Overview
Problem
Conventional nickel-based lithium transition metal oxides suffer from structural degradation and volume changes during charge and discharge, leading to cracks and reduced conductivity, which limits their capacity retention and increases resistance.
Innovation Solution
A nickel-based lithium composite transition metal oxide is developed with optimized crystallite size and reduced strain, achieved by adjusting sintering conditions to satisfy specific size and strain equations, minimizing cracks and enhancing capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content is increased to improve capacity characteristics, then capacity increases, but surface instability and structural degradation occur during charge and discharge
Solution Approach 1:
The patent optimizes the crystallite size parameter to a specific range (50-150 nm) to resolve the contradiction between high nickel content for capacity and surface stability. By controlling the crystallite size within this range, the material achieves both high capacity from high nickel content and improved surface stability that prevents degradation during charge-discharge cycles
Solution Approach 2:
The patent uses composite materials by combining nickel-based lithium transition metal oxide with other metal elements (such as cobalt, manganese, aluminum) to create a composite structure. This composite approach allows the material to achieve high capacity through high nickel content while the other elements provide structural stability and prevent surface degradation
2Quantity of substance
If nickel content is increased to improve capacity characteristics, then capacity increases, but volume changes in unit cell occur causing cracks
Solution Approach 1:
The patent controls the crystallite size parameter within 50-150 nm to minimize volume changes in the unit cell during charge and discharge. This parameter optimization reduces the expansion and contraction that causes cracks, thereby maintaining structural integrity while still achieving high capacity through high nickel content
Solution Approach 2:
The patent applies beforehand cushioning by pre-optimizing the crystallite size and compositional ratios before the material undergoes charge-discharge cycling. This pre-optimization creates a more resilient structure that can withstand the mechanical stresses of volume changes, preventing crack formation before they occur
3Reliability
If coating or doping is applied to prevent cracks, then structural stability improves, but additional cost and manufacturing complexity increase
Solution Approach 1:
The patent applies self-service by designing the nickel-based lithium transition metal oxide material to inherently possess structural stability through optimized crystallite size (50-150 nm) and compositional ratios. The material structure itself provides crack prevention without requiring external coating or doping processes, thereby maintaining structural stability while avoiding additional manufacturing complexity and cost
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 optimized nickel-based lithium composite transition metal oxide minimizes cracks, increases capacity retention, and suppresses resistance increase, resulting in improved battery performance.
Implementation Method 1
electrical energy is produced by oxidation and reduction reactions when the lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Implementation Method 2
achieved by adjusting sintering conditions to satisfy specific size and strain equations
Data Source
AI summary
A positive electrode active material for a secondary battery which includes a: nickel-based lithium composite transition metal oxide including nickel (Ni), wherein the lithium composite transition metal oxide satisfies Equation 2: [Equation 2]Δ size (| crystallite sizeIB-crystallite sizeFWHM|) ≤20, wherein, in Equation 1 and Equation 2, crystallite sizeFWHM is a crystallite size obtained by calculating from X-ray diffraction (XRD) data using a full width at half maximum (FWHM) method, and crystallite sizeIB is a crystallite size obtained by calculating from XRD data using an integral breadth (IB) method.