Li-Ni Composite Oxide Particles for Battery Cathodes
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Solution Overview
Problem
Current Li-Ni composite oxides for non-aqueous electrolyte secondary batteries face challenges in achieving high discharge capacity and first-cycle charge/discharge efficiency due to instability in crystal structure and increased reactivity with electrolytes, leading to deteriorated cycle characteristics and energy density.
Innovation Solution
Li-Ni composite oxide particles with a composition of Li x (Ni y Co 2(1-y)/5 Mn 3(1-y)/5 ) 1-z M z O 2, where x, y, and z are within specific ranges, and M is Al, Zr, or Mg, are produced by mixing lithium and Ni-Co-Mn hydroxide particles with optional aluminum or zirconium compounds, calcined in an oxidative atmosphere, to control metal occupancy and crystallite size for enhanced stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li is extracted from LiNiO2 to increase discharge capacity, then charge/discharge capacity is improved, but crystal structure suffers from Jahn-Teller distortion and first-cycle charge/discharge efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lithium content (x) to be 1.00 ≤ x ≤ 1.10 and the metal occupancy in lithium sites to be 2-7%. This controlled parameter range prevents excessive lithium extraction that would cause Jahn-Teller distortion, while still achieving high discharge capacity. The specific parameter ranges optimize both capacity and structural stability.
Solution Approach 2:
The patent uses composite materials by incorporating multiple metal elements (Ni, Co, Mn) in specific ratios within the Li-Ni composite oxide structure. This composite approach stabilizes the crystal structure during lithium extraction, preventing Jahn-Teller distortion while maintaining high capacity. The multi-element composition provides structural robustness that single-element materials cannot achieve.
2Quantity of substance
If Li-Ni composite oxide particles are densely aggregated to form secondary particles with high packing density, then discharge capacity is improved, but particles are broken by compression and reactivity with electrolyte increases
Solution Approach 1:
The patent applies parameter changes by controlling particle size (1-20 μm) and specific surface area (0.1-1.6 m²/g) within optimal ranges. These parameter adjustments ensure high packing density for capacity while limiting surface area to reduce electrolyte reactivity and prevent particle breakage during compression.
Solution Approach 2:
The patent applies local quality by creating a controlled surface structure with specific metal occupancy (2-7% in lithium sites) that provides local stability at particle boundaries. This localized structural optimization prevents breakage at compression points and reduces reactivity at surface sites, while maintaining high capacity in the bulk material.
3Quantity of substance
If Li-Ni composite oxide has high discharge capacity, then energy density is improved, but first-cycle charge/discharge efficiency is low requiring excessive negative electrode material
Solution Approach 1:
The patent applies parameter changes by optimizing lithium content (x = 1.00-1.10) and metal occupancy (2-7%) to achieve high discharge capacity while minimizing irreversible capacity loss. This precise parameter control ensures that the first-cycle charge/discharge efficiency is improved, reducing the need for excessive negative electrode material and optimizing energy density.
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 controlled composition and production process result in Li-Ni composite oxide particles with improved diffusion paths, minimized crystal structure changes, and suppressed reactivity, achieving high charge/discharge capacity and efficiency, suitable for use as a positive electrode active substance in non-aqueous electrolyte secondary batteries.
Implementation Method 1
calcined in an oxidative atmosphere
Implementation Method 2
calcined in an oxidative atmosphere
Implementation Method 3
improved diffusion paths
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to Li-Ni composite oxide particles having a composition of Lix(NiyCo2(1-y)/5Mn3(1-y)/5)1-zMzO2 wherein x, y and z represent 1.00 ≤ x ≤ 1.10; 0.65 < y < 0.82; and 0 ≤ z < 0.05, respectively; and M is at least one element selected from the group consisting of Al, Zr and Mg. The Li-Ni composite oxide particles of the present invention exhibit a high initial discharge capacity and are excellent in first-cycle charge/discharge efficiency when used as a positive electrode active substance for non-aqueous electrolyte secondary batteries.