Magnesium Composite Oxide Positive Electrode for Secondary Batteries
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Solution Overview
Problem
Magnesium composite oxides used as positive electrode active materials in magnesium secondary batteries exhibit low discharge capacity, making it difficult to achieve favorable charge-discharge characteristics.
Innovation Solution
A positive electrode active material with a rock salt-type crystal structure, represented by the formula MgxM1yM2zO2, where M1 is Ni, Co, or Mn, and M2 is selected from Ni, Co, Mn, Ti, V, Cr, Fe, Cu, Nb, W, or Ru, with specific stoichiometric ratios of x, y, and z optimized for improved charge-discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional magnesium composite oxides (e.g., Mg0.67Ni1.33O2, MgNiO2) are used as positive electrode active materials, then the battery structure is simple and manufacturing is easy, but the discharge capacity is small and charge-discharge characteristics are poor
Solution Approach 1:
The invention changes the compositional parameters of the magnesium composite oxide by introducing a three-component system (Mg-M1-M2) with specific stoichiometric ratios (0.3≤x≤1.0, 0.1<y≤0.7, 0.1<z≤0.7) to optimize discharge capacity while maintaining the rock salt-type crystal structure
Solution Approach 2:
The invention creates a composite oxide material combining Mg with two different transition metal elements (M1 and M2) in a rock salt-type structure, where M1 and M2 are selected from specific element groups, to achieve synergistic effects that improve both capacity and charge-discharge characteristics
2Quantity of substance
If the composition of magnesium composite oxide is optimized for high discharge capacity, then charge-discharge characteristics improve, but the crystal structure complexity increases
Solution Approach 1:
The invention optimizes the compositional parameters (x, y, z ratios) within specific ranges to achieve high discharge capacity while maintaining the simple rock salt-type crystal structure (space group Fm-3m), avoiding complex crystal phases
Solution Approach 2:
The invention assigns different functional roles to different metal elements in the composite oxide: Mg provides the basic rock salt structure, M1 (Ni, Co, or Mn) contributes to electronic properties, and M2 (from the specified group) enhances capacity, with each element occupying specific sites in the crystal lattice
Data Source
AI summary
A positive electrode active material for a magnesium secondary battery, and a positive electrode for a magnesium secondary battery and a magnesium secondary battery in which the positive electrode active material is used are provided. The positive electrode active material consists of a magnesium composite oxide which is represented by Formula (1): MgxM1yM2zO2 and which has a rock salt-type crystal structure of space group Fm-3m. In Formula (1), M1 is Ni, Co, or Mn, M2 is different from M1 and is at least one element selected from the group consisting of Ni, Co, Mn, Ti, V, Cr, Fe, Cu, Nb, W, Mo, and Ru, 0<x≤1, 0<y<2, 0<z<1; and 1.5≤x+y+z≤2.0.