Sodium-Doped Spinel Cathode for High-Capacity Lithium-Ion Batteries
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Solution Overview
Problem
Existing positive electrode active materials for non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, do not adequately address the need for increased capacity, particularly in applications requiring higher energy density.
Innovation Solution
A positive electrode active material with a crystal structure belonging to the space group R-3m, containing a predetermined amount of sodium (Na) and oxygen deficiency, is used, enhancing electronic conductivity and structural stability, thereby improving charge-discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-transition metal composite oxide with layered structure is used as positive electrode active material, then the battery can operate with basic performance, but the capacity is insufficient for high energy density applications
Solution Approach 1:
The invention changes the crystal structure parameter from layered structure to spinel structure (space group Fd-3m), and introduces oxygen deficiency (d > 0) to modify the electronic structure. This parameter change enables higher capacity while maintaining structural stability, directly resolving the contradiction between basic operation and high energy density requirement
Solution Approach 2:
The invention uses a composite oxide containing Li, transition metals (Ni, Mn, Co), and main-group elements (Al, Ga, In, B, P, Si, Ge, Sn) in a spinel structure. This composite material approach allows optimization of both capacity and energy density by combining multiple elements with complementary properties
2Quantity of substance
If oxygen deficiency is introduced into lithium-transition metal composite oxide to increase capacity, then the charge-discharge capacity improves, but the structural stability may deteriorate
Solution Approach 1:
The invention precisely controls the oxygen deficiency parameter (d) within the range 0 < d ≤ 0.25, and combines it with specific metal ratios (0.3 ≤ b ≤ 0.7 for Ni, 0.2 ≤ a ≤ 0.5 for Mn) to achieve optimal balance between capacity enhancement and structural stability in the spinel structure
Solution Approach 2:
The invention introduces oxygen deficiency selectively in the spinel structure while maintaining specific elemental distributions (Ni at b sites, Mn at a sites, main-group elements as dopants). This local quality control ensures that oxygen deficiency enhances capacity without causing widespread structural degradation
3Quantity of substance
If the crystal structure is changed to spinel structure with oxygen deficiency, then the electronic conductivity and capacity increase, but the manufacturing precision requirements increase
Solution Approach 1:
The invention defines specific parameter ranges for compositional control (0.3 ≤ b ≤ 0.7 for Ni, 0.2 ≤ a ≤ 0.5 for Mn, 0 < d ≤ 0.25 for oxygen deficiency) that balance electronic conductivity enhancement with manufacturability. These parameter specifications make high-precision synthesis achievable through conventional methods
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 introduction of sodium and controlled oxygen deficiency in the layered rock-salt structure significantly increases the charge-discharge capacity of non-aqueous electrolyte secondary batteries.
Implementation Method 1
a positive electrode active material for a non-aqueous electrolyte secondary battery, having a crystal structure belonging to the space group R-3m, and being represented by a compositional formula Li α Na β Ni 1-b-c Mn b X c O 2-d wherein X represents at least one selected from the group consisting of transition metal elements or main-group elements other than Li, Na, Ni, and Mn; and 0.80
Data Source
Figure 1
AI summary
A positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention has a crystal structure belonging to space group R-3m and is represented by the compositional formula LiαNaβNi1-b-cMnbXcO2-d, wherein X is at least one element selected from the group consisting of typical elements and transition metal elements other than Li, Na, Ni, and Mn, 0.80 < α ≤ 1.20, 0 < β ≤ 0.20, 0.80 < α + β ≤ 1.20, 0 < 1-b-c ≤ 1, 0 ≤ b < 1, 0 ≤ c < 1, and 0 < d ≤ 0.2.