Sodium Oxide Positive Electrode for High Energy Density Batteries
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries using lithium-containing transition metal composite oxides face challenges in achieving high energy density due to degradation of crystal structure and reversibility when lithium is extracted, leading to limited discharge capacity and cycle performance.
Innovation Solution
A non-aqueous electrolyte secondary battery with a positive electrode active material comprising sodium oxide, represented by the formula NaaLibMxO2±α, where 0.5≦a≦1.0, 0<b<0.5, 0.6≦a+b≦1.1, 0.90≦x≦1.10, and 0≦α≦0.1, which reduces the load on the crystal structure by controlling the lithium amount less than sodium, allowing for high discharge capacity and stable structure even at high potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-containing transition metal composite oxide is used as positive electrode active material, then high energy density is achieved, but crystal structure degrades and reversibility deteriorates when lithium is extracted
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by introducing sodium oxide components and controlling the ratio of lithium to sodium. This compositional parameter change allows the material to achieve high energy density while maintaining crystal structure stability during lithium extraction, resolving the contradiction between energy density and structural reliability.
Solution Approach 2:
The patent creates a composite positive electrode active material containing both lithium-containing transition metal composite oxide and sodium oxide. This composite structure combines the high energy density characteristics of lithium-based materials with the structural stability of sodium-based materials, enabling simultaneous achievement of high energy density and reliable crystal structure during charge-discharge cycles.
2Quantity of substance
If lithium is extracted to increase discharge capacity, then higher energy density is achieved, but crystal structure degradation occurs
Solution Approach 1:
The patent modifies the compositional parameters of the positive electrode active material by incorporating sodium oxide and controlling Li/Na ratios. This parameter change enables greater lithium extraction (up to 50% or more) to achieve higher discharge capacity while the sodium components stabilize the crystal structure, preventing degradation that would normally occur at such high extraction levels.
3Quantity of substance
If conventional lithium-based positive electrode material is used, then high discharge capacity is achieved, but cycle performance deteriorates due to structure degradation
Solution Approach 1:
The patent develops a composite positive electrode active material combining lithium-containing transition metal composite oxide with sodium oxide. This composite structure maintains high discharge capacity from lithium extraction while the sodium oxide components provide structural stability during repeated charge-discharge cycles, significantly improving cycle performance compared to conventional lithium-only materials.
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 battery achieves high discharge capacity and good cycle performance with stable structure, even when lithium is extracted to a high potential, and exhibits little electrolyte decomposition, maintaining performance during charge-discharge cycles.
Implementation Method 1
the charge-discharge operations are performed by migration of lithium ions between the positive and negative electrodes
Implementation Method 2
by ion-exchanging sodium for lithium
Data Source
AI summary
A non-aqueous electrolyte secondary battery having a negative electrode, a non-aqueous electrolyte, and a positive electrode having a positive electrode active material comprising sodium oxide, is characterized in that the sodium oxide contains lithium, and the molar amount of the lithium is less than the molar amount of the sodium.