Sodium Battery Positive Electrode Material with Carbon Coating
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Solution Overview
Problem
Sodium batteries face challenges with low operating potential, poor electron conductivity, and limited practical use due to the lack of suitable negative electrode active materials that ensure sufficient electromotive force and high electron conductivity, especially when using MoP2O7 as the positive electrode material.
Innovation Solution
A positive electrode material for sodium batteries is developed, comprising particles represented by the formula Na x M y (AO4) z (P2O7) with an electroconductive carbonaceous material coating, where M is a transition metal and A is an element like Al, Si, or P, exhibiting a crystal structure attributed to space group Pn2 1 a, enhancing Na ion conductivity and operating potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If MoP2O7 is used as the positive electrode active material, then the sodium battery can operate, but the operating potential is low
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by introducing multiple transition metals (Mn, Ni, Co) and varying their ratios, along with adjusting the P2O7 content. This compositional parameter optimization enables achieving both high operating potential (4.2V or higher) and sufficient electromotive force simultaneously, resolving the contradiction between operating potential and electromotive force reliability
Solution Approach 2:
The patent develops a composite positive electrode active material containing multiple transition metals (Mn, Ni, Co) in specific ratios, combined with P2O7. This composite structure leverages the synergistic effects of different metals to achieve both high operating potential and adequate electromotive force, overcoming the limitations of single-metal compounds like MoP2O7
2Ease of manufacture
If an active material with small electron conductivity is used, then the material can be processed, but the electrical resistance upon charging and discharging is large
Solution Approach 1:
The patent optimizes the electron conductivity parameter by carefully controlling the ratios of transition metals (Mn, Ni, Co) and the content of P2O7 in the composite active material. This parameter optimization achieves sufficient electron conductivity to reduce electrical resistance during charging and discharging, while maintaining processability, thereby resolving the contradiction between ease of manufacture and reliability of capacity
3Use of energy by moving object
If the positive electrode active material operates at high potential, then the energy density increases, but the electron conductivity requirement becomes more stringent
Solution Approach 1:
The patent employs a composite material system containing multiple transition metals (Mn, Ni, Co) with optimized ratios, combined with P2O7. This composite structure provides both the high operating potential (4.2V or higher) needed for high energy density and the sufficient electron conductivity required to support high-potential operation, resolving the contradiction between energy density and electron conductivity reliability
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 solution provides a positive electrode material with high operating potential, excellent electron conductivity, increased energy density, and improved charge-discharge efficiency and capacity, enabling practical application of sodium batteries.
Implementation Method 1
an electroconductive carbonaceous material that coats at least part of the surface of the positive electrode active material particles
Implementation Method 2
when the MOP 2 O 7 is used as the positive electrode active material of a sodium battery, the operation of the sodium battery is needed to be started by insertion of Na ions (discharge reaction)
Data Source
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AI summary
The invention is to provide a positive electrode material for sodium batteries, which has high operating potential and enable charging and discharging at high potential, and a method for producing thereof. Disclosed is a positive electrode material for sodium batteries, comprising positive electrode active material particles represented by the following general formula (1), and an electroconductive carbonaceous material that coats at least part of the surface of the positive electrode active material particles: General Formula (1): NaxMy(AO4)z(P2O7)w wherein M is at least one selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn; A is at least one selected from the group consisting of Al, Si, P, S, Ti, V and W; x is a value that satisfies 4≥x≥2; y is a value that satisfies 4≥y≥1; z is a value that satisfies 4≥z≥0; w is a value that satisfies 1≥w≥0; and at least one of z and w is 1 or more.