Solid Electrolyte with Niobium Tantalum Oxide
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Solution Overview
Problem
Lithium ion batteries with high electromotive force face challenges due to the instability of positive and negative electrodes when used with solid electrolytes, leading to increased self-discharge caused by electron conductivity within the electrolyte, which impairs insulation and reduces battery lifespan.
Innovation Solution
A solid electrolyte material with an octahedral coordination structure incorporating niobium (Nb) and a small amount of tantalum (Ta) is developed, with a mass ratio of Ta to Nb within 5×10−5 to 3×10−3, enhancing reduction resistance and ion conductivity while maintaining chemical stability and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high electromotive force materials are used in lithium ion batteries, then energy density is improved, but electrode stability deteriorates leading to increased self-discharge
Solution Approach 1:
The patent introduces a solid electrolyte as an intermediary layer between the positive and negative electrodes. This solid electrolyte acts as a mediator that prevents direct contact and harmful reactions between the high electromotive force electrode materials, thereby reducing self-discharge while maintaining high energy density. The solid electrolyte specifically blocks electron conductivity pathways that would otherwise cause self-discharge in batteries using high electromotive force materials.
Solution Approach 2:
The patent changes the physical and chemical parameters of the electrolyte from liquid to solid state, and specifically optimizes the composition of the solid electrolyte (using lithium lanthanum zirconate as base with aluminum and niobium additives). This parameter change transforms the electrolyte's properties to achieve both high ion conductivity and low electron conductivity, enabling the use of high electromotive force electrode materials without suffering from self-discharge issues.
2Reliability
If solid electrolyte is used instead of liquid electrolyte, then safety and lifespan are improved, but electron conductivity within electrolyte causes self-discharge
Solution Approach 1:
The patent optimizes the compositional parameters of the solid electrolyte by adding specific amounts of aluminum (0.01-0.5 mol per mole of lithium lanthanum zirconate) and niobium (0.01-0.5 mol per mole of lithium lanthanum zirconate). These parameter changes adjust the electrolyte's electronic and ionic conductivity properties, maintaining the safety and lifespan benefits of solid electrolytes while suppressing harmful electron conductivity that causes self-discharge.
Solution Approach 2:
The patent creates a composite solid electrolyte material by combining lithium lanthanum zirconate with aluminum and niobium additives. This composite approach leverages the high ion conductivity of lithium lanthanum zirconate while the aluminum and niobium components suppress electron conductivity, thereby eliminating self-discharge while preserving the inherent safety and longevity advantages of solid electrolyte systems.
3Productivity
If high ion conductivity solid electrolyte is used, then battery performance is improved, but chemical stability with high oxidizing and reducing electrode materials deteriorates
Solution Approach 1:
The patent develops a composite solid electrolyte combining lithium lanthanum zirconate with aluminum and niobium additives. This composite structure maintains the high ion conductivity needed for excellent battery performance while the aluminum and niobium components enhance chemical stability, preventing degradation reactions with high oxidizing power positive electrodes and high reducing power negative electrodes.
Solution Approach 2:
The patent applies local quality enhancement by adding specific elements (aluminum and niobium) at controlled concentrations to the solid electrolyte composition. These localized compositional adjustments create regions within the electrolyte that are specifically resistant to oxidation and reduction, enabling the electrolyte to maintain high ion conductivity while achieving the chemical stability required for use with high electromotive force electrode 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 solid electrolyte material achieves high reduction resistance and flexibility, reducing self-discharge and improving the stability and lifespan of lithium ion batteries while maintaining cost-effectiveness.
Implementation Method 1
lithium ion conductivity of 5×10−4 S/cm or more, which is top class among oxide solid electrolytes, at room temperature
Implementation Method 2
there is no concern for liquid leakage of an organic electrolytic solution or gas generation... a low probability of side reactions other than battery reactions
Data Source
AI summary
According to one embodiment, provided is a solid electrolyte material including an oxide, the oxide including an octahedral coordination structure that includes a metal element M and oxygen atoms arranged centering on the metal element M. The metal element M includes Nb and Ta. Amass ratio αTa/αNb of a mass αTa of Ta to a mass αNb of Nb is within a range of 5×10−5≤αTa/αNb≤3×10−3.