Li-ion Battery Cathode Material with Disordered NaCl Structure
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Solution Overview
Problem
Lithium-ion battery cathode materials with disordered NaCl structure, such as Li2NiTiO4, suffer from low ion conductivity and structural instability due to oxygen participation in electrochemical processes, limiting their performance and capacity.
Innovation Solution
A new cathode material with the formula Li2+xNiTuNbO4, where x, u, and v are within specific ranges, exhibits improved ion conductivity and theoretical specific capacity exceeding 250 mAh/g by substituting titanium with nickel and/or niobium, avoiding oxygen oxidation and enhancing lithium diffusion paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2NiTiO4-type materials with disordered NaCl structure are used, then theoretical capacity is high (290 mAh/g), but ion conductivity is too low
Solution Approach 1:
The patent modifies the stoichiometric parameters of the Li2NiTiO4 material by introducing excess lithium (x>0) and substituting titanium with nickel and/or niobium in specific ratios. This changes the chemical composition parameters to Li2+xNi1-y-zTiyNbzO4, where the parameter adjustments optimize both capacity and ion conductivity simultaneously
Solution Approach 2:
The patent creates a composite cathode material by combining multiple elements (Li, Ni, Ti, Nb, O) in a specific disordered NaCl structure. The composite nature with controlled substitution of Ti by Ni and Nb creates synergistic effects that improve ion conductivity while maintaining high theoretical capacity
2Quantity of substance
If superstoichiometric layered lithium oxides are used, then specific capacity is proper (250 mAh/g), but structural instability occurs due to oxygen participation
Solution Approach 1:
The patent transitions from layered oxide structure to disordered NaCl structure by changing the crystallographic parameters and stoichiometry. The formula Li2+xNi1-y-zTiyNbzO4 with x>0 creates a structure where oxygen remains in its oxide state rather than participating in redox reactions, thereby maintaining structural stability while achieving proper capacity
Solution Approach 2:
The patent converts the harmful effect of oxygen participation (which causes structural instability) into a beneficial configuration where oxygen remains stable in the lattice. By using the disordered NaCl structure with excess lithium, the oxygen atoms are stabilized and do not participate in electrochemical reactions, eliminating the instability problem while preserving capacity
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 material achieves higher ion conductivity and stable capacity without oxygen involvement, demonstrating enhanced performance and stability in lithium-ion batteries through increased percolation paths and reduced structural instability.
Implementation Method 1
the substitution of titanium with lithium and with a metal (nickel and/or niobium) enables to improve its ion conductivity and thus its performance
Implementation Method 2
The material according to the invention enables to reach 250 mAh/g without involving an electrochemical activity of the oxygen of the lattice due to the Ni2+/Ni4+ couple
Data Source
AI summary
An electrode material of formula Li2+xNiuTivNbwO4 where:0<x<0.3,u>0 and w>0,x+u+v+w=2,x+2u+4v+5w=6,the electrode material having a crystal structure of disordered NaCl type. A cathode having this material as an electronically active material and also the lithium-ion battery containing this cathode are also contemplated.