Lithium Nickel Composite Oxide Cathode for High Capacity Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high capacity and long cycle-life characteristics due to the limitations of nickel-based composite oxides, which suffer from reduced stability and capacity degradation due to excessive residual lithium on the surface.
Innovation Solution
A cathode active material using lithium nickel composite oxide with a specific c-axis lattice parameter range (14.1720 Å ≤ c ≤ 14.1750 Å) is developed, achieved through a production method involving mixing nickel and lithium precursors, primary firing, washing, drying, and secondary firing, to minimize surface lithium and enhance structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based composite oxide is used to increase battery capacity, then capacity is improved, but cycle-life characteristics deteriorate due to excessive residual lithium on the surface
Solution Approach 1:
The patent extracts and removes excessive residual lithium from the surface of the nickel-based composite oxide particles through a washing process. This is achieved by suspending the particles in water and removing lithium ions from the surface, thereby reducing the harmful residual lithium while preserving the high-capacity nickel-based composite oxide structure.
Solution Approach 2:
The patent performs preliminary washing and drying treatments after the primary firing process but before the secondary firing process. This preliminary removal of residual lithium prevents the formation of harmful surface compounds during secondary firing and ensures stable cycle-life characteristics in the final product.
2Reliability
If residual lithium on the surface is reduced through washing, then cycle-life characteristics are improved, but manufacturing complexity increases due to additional washing and drying steps
Solution Approach 1:
The patent combines the washing and drying steps into an integrated treatment process that is performed between primary and secondary firing. By merging these steps and optimizing the water-to-particle ratio and drying conditions, the process achieves effective residual lithium removal without requiring separate, complex manufacturing stages.
3Reliability
If washing is performed to remove residual lithium, then cycle-life characteristics are improved, but lithium loss increases during the washing process
Solution Approach 1:
The patent applies local quality by selectively removing lithium from the surface region of the particles while preserving the bulk composition. The washing process targets only the residual lithium on the particle surfaces, maintaining the high-capacity nickel-based composite oxide structure in the interior and minimizing overall lithium loss.
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 approach results in a lithium secondary battery with improved cycle-life characteristics and high capacity, as evidenced by the stabilization of the crystal structure during lithium ion intercalation/deintercalation and reduced impurity formation.
Implementation Method 1
a structure capable of intercalating lithium ions
Implementation Method 2
washing the same
Data Source
AI summary
The present disclosure relates to a cathode active material for a lithium secondary battery, a method for preparing same, and a lithium secondary battery comprising same, the cathode active material comprising a lithium-nickel compound oxide, wherein a c-axis lattice parameter of a unit lattice of the lithium-nickel compound oxide satisfies Formula 1:14.1720 ÅA≤c≤14.1750 ÅA [Formula 1]