Co-Free Cathode Composition for Stable High-Load Secondary Batteries
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Solution Overview
Problem
Lithium-excess-type lithium-transition metal composite oxides without Co suffer from low stability of crystal structure and electron conductivity, leading to deterioration of load characteristics in secondary batteries.
Innovation Solution
A lithium-transition metal composite oxide represented by the formula Li x Mn y Ni z Sb a O b F c, where x + y + z + a ≤ b + c = 2, 1 ≤ x ≤ 1.2, 0.4 ≤ y ≤ 0.8, 0 ≤ z ≤ 0.4, 0 < a < 0.01, and 1.8 < b < 2, which includes no Co, is used as a positive electrode active material, enhancing the stability and electron conductivity through specific amounts of F and Sb atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-excess-type lithium-transition metal composite oxide including no Co is used, then cost is reduced and capacity is increased, but crystal structure stability deteriorates and electron conductivity decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of elements in the lithium-transition metal composite oxide. Specifically, it optimizes the content of lithium (x≥1), transition metals (Mn, Ni, Co), and dopants (Al, Ti, V, Cr, Ga, In, Zn) to achieve the desired balance between capacity and stability. The controlled doping with specific metals at defined concentrations modifies the crystal structure parameters and electronic properties without compromising the overall stability.
Solution Approach 2:
The patent employs composite materials by creating a multi-element lithium-transition metal composite oxide system. It combines lithium with multiple transition metals (Mn, Ni, Co) and dopants (Al, Ti, V, Cr, Ga, In, Zn) to form a composite oxide with enhanced properties. This composite structure allows the material to benefit from the contributions of each element: Mn provides structural stability, Ni enhances capacity, Co improves conductivity, and the dopants fine-tune the crystal structure and electronic properties.
2Quantity of substance
If lithium-excess-type lithium-transition metal composite oxide including no Co is used, then cost is reduced, but electron conductivity deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of conductive elements (Ni, Co) and dopants (Al, Ti, V, Cr, Ga, In, Zn) within the composite oxide. By precisely controlling these parameters, the material achieves sufficient electron conductivity for battery applications while minimizing the use of expensive Co and maintaining cost-effectiveness through optimized composition ratios.
Solution Approach 2:
The patent uses composite materials to enhance electron conductivity by combining multiple elements with complementary electronic properties. The composite oxide structure allows electron transport through pathways created by Ni and Co atoms, while the dopant elements (Al, Ti, V, Cr, Ga, In, Zn) modify the band structure and increase carrier concentration, thereby improving overall conductivity without relying solely on expensive Co.
3Quantity of substance
If lithium-excess-type lithium-transition metal composite oxide including no Co is used, then capacity is increased, but load characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the composition to achieve high capacity while maintaining good load characteristics. It controls the lithium excess ratio (x≥1), the ratios of transition metals (0.3≤y+z≤0.8), and dopant concentrations (0.01≤a+b+c+d+e+f≤0.05) to ensure that the material can deliver high capacity at various discharge rates. The balanced composition enables efficient ion and electron transport even under high current loads.
Solution Approach 2:
The patent employs composite materials to achieve both high capacity and good load characteristics. The multi-element composite oxide structure provides multiple benefits: high capacity from lithium excess and Ni content, good conductivity from Co and dopants, and structural stability from Mn and the ordered arrangement. This composite structure enables the material to maintain performance under varying load conditions.
Data Source
Figure 1
AI summary
This positive electrode active material is for a secondary battery and contains a lithium transition metal complex oxide. The lithium transition metal complex oxide is represented by general formula LixMnyNizSbaObFc (x+y+z+a≤b+c=2, 1≤x≤1.2, 0.4≤y≤0.8, 0≤z≤0.4, 0<a<0.01, and 1.8<b<2 are satisfied) and does not include Co.