Spinel Solid Electrolyte Composition for 5 V Lithium Batteries
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Solution Overview
Problem
Conventional Li-ion battery electrolytes are flammable, unstable at high voltages, reactive with air, form impurity phases at interfaces, and have poor Li-ion conductivity, limiting the use of high-energy cathodes and high discharge rates in solid-state batteries.
Innovation Solution
Development of a spinel-structured solid electrolyte composition Li1+x+zM(II)0.5−2x−zM(III)x+yM(IV)1.5−2y−zM(V)yM(V)zO4, which forms an electrochemically-active solid solution with Li3BO3 (LBO) and spinel electrodes, enabling high Li+ conductivity and stable operation near 5 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Li-ion battery electrolytes are used, then the battery can operate, but the electrolyte is flammable and unstable at high voltages
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by doping Li1-xMgAl0.5Ti1.5O4 spinel with Al, Cr, Fe, Ga, or In at the A-site and Nb, Ta, Sb, or Bi at the B-site. This compositional modification transforms the electrolyte from flammable conventional types to stable oxide-based solid electrolytes that can operate at high voltages up to 5V without decomposition
Solution Approach 2:
The patent creates composite solid electrolyte materials by combining spinel-structured Li1-xMgAl0.5Ti1.5O4 with other oxides or forming composite structures with electrodes. This composite approach integrates the advantages of spinel structure (fast Li-ion conduction) with the stability of oxide materials, eliminating flammability while maintaining electrochemical performance
2Device complexity
If solid-state electrolyte interfaces are formed between solid electrolyte and solid cathode, then the battery structure is simplified, but poor Li+ ion conduction and impurity phase formation occur at interfaces
Solution Approach 1:
The patent achieves homogeneous integration of electrolyte and electrode by forming solid solutions where the spinel electrolyte composition Li1+x+zM(II)0.5−2x−zM(III)x+yM(IV)1.5−2y−zM(V)yM(V)zO4 is compatible with spinel electrode structures. This homogeneity eliminates sharp phase boundaries and interfacial impurity layers, enabling continuous Li+ ion conduction pathways throughout the solid-state battery
Solution Approach 2:
The patent uses the spinel structure itself as an intermediary material that is compatible with both electrolyte and electrode functions. The spinel electrolyte forms intermediate solid solution phases with spinel electrodes (such as LiNi0.5Mn1.5O4, LiMn2O4, or Li4Ti5O12), acting as a mediator that maintains structural integrity and Li+ conductivity across what would otherwise be incompatible interfaces
3Power
If high discharge rates are used, then power output increases, but poor Li-ion conductivity of electrode materials limits full Li-ion capacity achievement
Solution Approach 1:
The patent modifies the Li-ion conductivity parameter of the electrode materials by using spinel-structured compositions with specific cation distributions. The spinel electrolyte and electrode materials both exhibit high Li-ion conductivity due to their three-dimensional conduction pathways (8a→16c→8a), enabling the battery to deliver high power at high discharge rates while maintaining full Li-ion capacity
Solution Approach 2:
The patent creates multi-functional spinel materials that simultaneously serve as electrolyte, electrode, or coating layer. The spinel structure provides universal high Li-ion conductivity and electronic conductivity properties that benefit both power output and capacity retention, allowing the same material class to address multiple performance requirements
4Quantity of substance
If 5V cathodes such as LiNi0.5Mn1.5O4 are used, then energy density increases, but conventional electrolytes are unstable at greater than 4.5V
Solution Approach 1:
The patent changes the electrochemical stability window parameter of the electrolyte by using oxide-based spinel materials instead of conventional organic electrolytes. The oxide electrolyte Li1+x+zM(II)0.5−2x−zM(III)x+yM(IV)1.5−2y−zM(V)yM(V)zO4 remains stable at potentials up to 5V vs. Li/Li+, enabling the use of high-energy 5V cathodes like LiNi0.5Mn1.5O4 without electrolyte decomposition
Solution Approach 2:
The patent replaces expensive and unstable conventional electrolytes with abundant, stable oxide materials. The spinel electrolyte uses common elements (Li, Mg, Al, Ti, O) that are inexpensive and provide long-term stability at high voltages, making high-energy cathodes economically viable
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 new solid electrolyte composition achieves fast Li-ion conductivity, stability in air, and eliminates multi-phase interface incompatibilities, enabling high-rate charge and discharge in solid-state batteries.
Implementation Method 1
Li occupies the 8a tetrahedral site and shares faces with an empty 16c octahedral site, thus forming a three-dimensional 8a→16c→8a conduction pathway
Implementation Method 2
The solid-state electrolytes form an electrochemically-active solid solution with a spinel electrode
Data Source
AI summary
A composition of matter and method includes Li1+x+zM(II)0.5−2x−zM(III)x+yM(IV)1.5−2y−zM(V)yM(V)zO4. M(II) includes any of Mg, Co, Ni, Cu, and Zn. M(III) includes any of Al, Cr, Fe, Ga, and In. M(IV) includes any of Ti, Mn, and Ge. M(V) includes any of Nb, Ta, Sb, and Bi. Additionally, 0≤x≤0.25, 0≤y≤0.75, 0≤z≤0.5, and (x+z)>0.