Sodium Ion Battery Cathode Material Composition Optimization
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Solution Overview
Problem
Sodium ion batteries face challenges with poor actual capacity and cycle performance due to the limitations of existing positive active materials, hindering their commercialization, and are prone to irreversible chemical reactions that lead to capacity loss and safety issues.
Innovation Solution
A positive electrode active material with a specific chemical composition and water content is developed, enhancing ionic and electronic conductivity, inhibiting the formation of sodium hydroxide and carbonate layers, and improving stability, thereby reducing side reactions and increasing capacity retention and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing positive active materials are used in sodium ion batteries, then the battery can operate, but the actual capacity and cycle performance are poor
Solution Approach 1:
The patent changes the chemical composition parameters of the positive active material by introducing specific dopants (Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) at controlled concentrations (0.01-0.10 mol ratio) to optimize both capacity and cycle performance simultaneously
Solution Approach 2:
The patent creates composite materials by combining layered oxide base materials with multiple dopant elements, forming a composite structure that leverages the benefits of each component to achieve both high capacity and long cycle life
2Ease of manufacture
If positive active materials are used without controlled water content, then material preparation is simpler, but irreversible chemical reactions occur forming sodium hydroxide and carbonate layers
Solution Approach 1:
The patent performs preliminary water content control during the material synthesis process, maintaining water content at 50-200 ppm before battery assembly to prevent subsequent formation of inactive sodium hydroxide and carbonate layers that would reduce capacity retention
Solution Approach 2:
The patent creates an inert environment by strictly controlling water content in the positive active material, preventing irreversible chemical reactions with moisture that would form harmful sodium hydroxide and carbonate layers on the material surface
3Productivity
If positive active materials have high reactivity, then charging/discharging capacity elaboration is improved, but interface side reactions increase
Solution Approach 1:
The patent optimizes the chemical composition parameters by introducing dopants at precise concentrations that enhance ionic conductivity and charging/discharging capacity while simultaneously suppressing interface side reactions through stabilized surface chemistry
4Reliability
If sodium ion diffusion is not hindered, then electrochemical performance is good, but sodium hydroxide and carbonate layers form on particle surfaces
Solution Approach 1:
The patent creates an inert environment by controlling water content to 50-200 ppm, preventing the formation of harmful sodium hydroxide and carbonate layers that would otherwise form through irreversible reactions with moisture, thereby maintaining good electrochemical performance
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 improved positive electrode active material results in higher charging/discharging capacity, cycle performance, and safety performance for sodium ion batteries by reducing irreversible reactions and hindrances to ion and electron diffusion, leading to enhanced electrochemical and safety performance.
Implementation Method 1
Sodium ion batteries can realize charging and discharging by a sodium ion intercalation-deintercalation process between positive and negative electrodes
Implementation Method 2
the positive electrode active material has relatively high ionic and electronic conductivity
Implementation Method 3
it effectively inhibits the formation of sodium hydroxide layer without electrochemical activity due to irreversible chemical reactions on the surface of particles
Data Source
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AI summary
The present application discloses a positive electrode active material and its preparation method, a sodium ion battery and an apparatus containing the sodium ion battery. The positive electrode active material satisfies a chemical formula of Na1-xCuhFekMnlMmO2-y wherein M is one or more selected from Li, Be, B, Mg, Al, K, Ca, Ti, Co,Ni, Zn, Ga, Sr, Y,Nb, Mo, In,Sn, and Ba, 0 < x ≤ 0.33, 0 < h ≤ 0.24, 0 ≤ k ≤ 0.32, 0 < l ≤ 0.68, 0 ≤ m < 0.1, h+k+l+m = 1, 0 ≤ y < 0.2, and the positive electrode active material has a water content of 6000 ppm or less.