Lithium Manganese Oxide Coated with Solid Electrolyte
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Solution Overview
Problem
Conventional lithium secondary battery positive electrode active materials face challenges such as low structural stability, high cost, and safety issues at high operating voltages, particularly with LiCoO2 and LiNiO2, which limit their use in electric vehicles due to resource constraints and phase transitions during charge-discharge cycles.
Innovation Solution
A positive electrode active material is developed by forming a lithium ion conductive glass-ceramic solid electrolyte layer on lithium-rich lithium manganese-based oxide particles, enhancing surface stability and conductivity, and allowing for higher voltage operation without the limitations of conventional surface coating techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich lithium manganese-based oxide is used to achieve high capacity at high voltage, then discharge capacity is improved, but surface stability deteriorates and electrolyte decomposition occurs
Solution Approach 1:
A solid electrolyte coating layer is introduced as an intermediary between the lithium-rich lithium manganese-based oxide particles and the liquid electrolyte. This coating layer prevents direct contact and chemical reactions between the active material surface and the liquid electrolyte, thereby suppressing electrolyte decomposition and maintaining surface stability during high-voltage operation while allowing ionic conductivity to be maintained
2Reliability
If conventional surface coating techniques are used to improve safety at high voltage, then surface stability is improved, but voltage operation is still limited and electrolyte decomposition continues
Solution Approach 1:
The invention changes the key parameter of the coating layer from conventional insulating metal oxides to lithium ion conductive solid electrolyte materials. This parameter change enables the coating layer to maintain high ionic conductivity while providing surface stability, allowing the battery to operate at higher voltages (4.5V or higher) without the limitations of conventional coating techniques
3Duration of action of stationary object
If LiCoO2 is used to achieve excellent lifetime characteristics and high charge-discharge efficiency, then cycle life is improved, but structural stability deteriorates and cost increases
Solution Approach 1:
The invention uses composite materials by coating solid electrolyte on lithium-rich lithium manganese-based oxide particles. This composite structure combines the high capacity advantages of lithium-rich materials with the protective benefits of solid electrolyte coating, achieving both excellent cycle life and structural stability at high voltage without relying on expensive LiCoO2
4Use of energy by moving object
If high-voltage driving is used to achieve high energy density, then energy density is improved, but irreversible capacity increases and oxygen escapes from the active material structure
Solution Approach 1:
The solid electrolyte coating layer is applied in advance to prevent oxygen escape and irreversible capacity loss before they can occur during high-voltage driving. This preliminary protective action suppresses the decomposition reactions that would otherwise lead to oxygen release and capacity degradation, enabling safe high-voltage operation for high energy density
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 solution provides excellent surface stability and increased conductivity at high voltages, improving the overall performance and safety of lithium secondary batteries by suppressing electrolyte decomposition and maintaining high ionic conductivity, thus enhancing battery cell performance.
Implementation Method 1
a lithium ion conductive glass-ceramic solid electrolyte layer containing at least one selected from the group consisting of thio-LISICON (thio-lithium super ionic conductor), LISICON (lithium super ionic conductor), Li2S—SiS2—Li4SiO4, and Li2S—SiS2—P2S5—Lil is formed on the surface of the lithium manganese-based oxide particle
Implementation Method 2
by forming a solid electrolyte layer having a specific composition on the surface of lithium-rich lithium manganese-based oxide, it exhibits excellent surface stability even in a high operating voltage range of 4.5 V or more and can increase the ionic conductivity and improve the overall performance of the battery cell
Data Source
AI summary
A positive electrode active material contains a lithium-rich lithium manganese-based oxide, wherein the lithium manganese-based oxide has a composition of the following chemical formula (1), and wherein a lithium ion conductive glass-ceramic solid electrolyte layer containing at least one selected from the group consisting of thio-LISICON(thio-lithium super ionic conductor), LISICON(lithium super ionic conductor), Li2S—SiS2—Li4SiO4, and Li2S—SiS2—P2S5—Lil is formed on the surface of the lithium manganese-based oxide particle:Li1−xMyMn1−x−yO2−zQz (1)wherein, 0<x≤0.2, 0<y≤0.2, and 0≤z≤0.5;M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Ga, In, Ru, Zn, Zr, Nb, Sn, Mo, Sr, Sb, W, Ti and Bi; andQ is at least one element selected from the group consisting of P, N, F, S and Cl.