Amorphous Nitrogen-Rich Solid Electrolyte for Stable Li-Ion Interfaces
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Solution Overview
Problem
Current solid-state lithium battery materials face challenges such as high production costs, limited stoichiometry leading to impurity phases, and mechanical degradation at the solid electrolyte-positive electrode interface due to elemental inter-diffusion and volume changes during charge and discharge.
Innovation Solution
The development of an amorphous nitrogen-rich lithium-ion conductor, represented by the compound Li7−a*α−(b−4)*β−xMaαLa3Zr2−βMbβO12−x−δXxNδ, which is cost-effectively manufactured using a method involving a nitrogen precursor, lithium precursor, lanthanum precursor, aluminum precursor, zirconium precursor, and a solvent, deposited at a low temperature to prevent undesirable reactions and improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional solid-state lithium battery materials (like LLZO) are used, then ionic conductivity is achieved, but production costs increase and mechanical degradation occurs at the solid electrolyte-positive electrode interface
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid electrolyte by incorporating nitrogen-rich compounds and adjusting the stoichiometry of lithium lanthanum zirconium oxide (LLZO) with dopants like Ta, Nb, or W. This compositional parameter change achieves both improved stability and maintained ionic conductivity while reducing production costs compared to traditional undoped LLZO materials.
Solution Approach 2:
The invention creates a composite solid electrolyte material combining LLZO base structure with nitrogen-rich compounds (such as Li3PO4, Li2SiO3, or other lithium phosphates/silicates containing nitrogen). This composite approach improves mechanical properties and interface stability while maintaining ionic conductivity, resolving the contradiction between reliability and manufacturing ease.
2Reliability
If solid electrolyte materials are used to improve battery stability, then mechanical degradation occurs at the solid electrolyte-positive electrode interface due to elemental inter-diffusion and volume changes
Solution Approach 1:
The patent introduces an intermediate buffer layer or modified interface composition between the solid electrolyte and positive electrode. This intermediate layer prevents direct elemental inter-diffusion and accommodates volume changes during charge-discharge cycles, thereby maintaining interface stability without compromising the compositional stability of the bulk solid electrolyte material.
Solution Approach 2:
The invention adjusts the compositional parameters at the solid electrolyte-positive electrode interface by incorporating specific dopants (Ta, Nb, W) and nitrogen-rich compounds that create a more stable interface region. This parameter modification reduces elemental inter-diffusion and accommodates volume changes, resolving the contradiction between interface stability and compositional stability.
3Use of energy by moving object
If lithium metal negative electrodes are used to improve energy density, then lithium dendrites propagate to the positive electrode and short-circuit the cell
Solution Approach 1:
The patent employs the amorphous nitrogen-rich solid electrolyte as an intermediary protective layer between the lithium metal negative electrode and the positive electrode. This intermediary layer effectively blocks lithium dendrite propagation while allowing lithium ion transport, thereby enabling the use of high-energy-density lithium metal electrodes without compromising safety.
Solution Approach 2:
The invention modifies the physical and chemical parameters of the solid electrolyte by creating an amorphous nitrogen-rich composition with specific ionic conductivity and mechanical properties. These parameter changes enable the electrolyte to effectively suppress dendrite growth while maintaining high ion transport efficiency, resolving the contradiction between energy density and safety.
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 amorphous nitrogen-rich lithium-ion conductor enhances the stability and ionic conductivity of lithium batteries, preventing mechanical degradation at the solid electrolyte-positive electrode interface and offering a more cost-effective solution compared to traditional materials like LLZO.
Implementation Method 1
amorphous nitrogen-rich lithium-ion conductor having improved stability and improved ionic conductivity
Implementation Method 2
deposited at a low temperature to prevent undesirable reactions and improve stability
Data Source
AI summary
A lithium ion conductor includes a compound of Formula 1:Li7−a*α−(b−4)*β−xMaαLa3Zr2−βMbβO12−x−δXxNδ Formula 1wherein in Formula 1,Ma is a cationic element having a valence of a,Mb is a cationic element having a valence of b, andX is an anion having a valence of −1,wherein, when Ma comprises H, 0≤α≤5, otherwise 0≤α≤0.75, andwherein 0≤β≤1.5, 0≤x≤1.5, (a*α+(b−4)β+x)>0, and 0<δ≤6.