Disordered Rock Salt Cathode Composition Without Fluorination
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Solution Overview
Problem
Existing methods for producing fluorinated disordered rock salt materials for lithium-ion batteries face challenges in scalability and safety due to the use of toxic chemicals and hazardous side reactions, limiting their industrial application and electrochemical performance.
Innovation Solution
Development of lithium metal oxide compositions with a disordered rock salt structure and lithium vacancies, which provide improved electrochemical performance without fluorination, using a non-stoichiometric composition and a synthesis method involving precursor materials and calcination, resulting in enhanced capacity, conductivity, and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorinated disordered rock salt materials are synthesised via high energy milling process using LiF, then electrochemical performance and capacity are enhanced, but production scalability is difficult and safety hazards increase
Solution Approach 1:
The patent changes the chemical composition parameters by substituting fluorine with oxygen and introducing lithium vacancies (non-stoichiometric composition Li1-xM1+yO2). This parameter change maintains the disordered rock salt structure while eliminating the need for LiF, enabling scalable production without compromising electrochemical performance
Solution Approach 2:
The patent replaces expensive and hazardous LiF with readily available metal oxides and oxygen from air during calcination. This substitution uses cheaper, safer materials that are easily obtainable and eliminate the need for specialized handling and disposal procedures required for LiF
2Quantity of substance
If fluorinated disordered rock salt materials are synthesised using LiF, then capacity is enhanced, but toxic and dangerous chemical hazards increase
Solution Approach 1:
The patent converts the harmful effect of fluorine (toxicity and reactivity) into a beneficial approach by using oxygen from air as the oxidizing agent during calcination. The Li2CO3 precursor decomposes to provide lithium and carbon dioxide, while oxygen from air completes the oxidation, eliminating toxic LiF waste while achieving the desired Li-rich composition
Solution Approach 2:
The patent introduces Li2CO3 as an intermediary precursor material that serves multiple functions: it provides lithium source, acts as a flux to facilitate solid-state reaction, and decomposes to release CO2 and O2 during calcination. This intermediary approach enables controlled synthesis without direct use of hazardous LiF
3Ease of manufacture
If high temperature calcination with fluorine is performed, then fluorinated DRX materials are produced, but side reactions with crucible increase
Solution Approach 1:
The patent converts the potential harm of high-temperature side reactions by replacing fluorine with oxygen. Oxygen from air is used as the oxidizing agent instead of reactive fluorine, which significantly reduces side reactions with the alumina crucible while still achieving complete oxidation and desired phase formation at high temperature
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 lithium metal oxide compositions exhibit improved electrochemical performance, including higher capacities, coulombic efficiency, and rate capability, while being easier to produce and safer than fluorinated materials, making them suitable for industrial use in lithium-ion batteries.
Implementation Method 1
For many years, cation disorder has been considered to be detrimental to Li+ transport (and thus to the reversible capacity) of intercalation-type electrodes
Implementation Method 2
M′ is redox-inactive d0 element. The role of the redox-inactive d0 element is described by Chen G. et al in 'Role of Redox-Inactive Transition-Metals in the Behaviour of Cation-Disordered Rocksalt Cathodes'
Data Source
AI summary
The present invention provides a lithium metal oxide composition, a method of synthesis of said composition, an electrode and a battery incorporating said composition, and a use of said composition. The lithium metal oxide composition has a cation-disordered rock salt structure, and a non-stoichiometric composition such that lithium vacancies are present in the material. The lithium metal oxide composition has a general formula: Li1+xM′yM1-x-y-βO2, wherein M comprises a transition metal element, M′ comprises a redox-inactive d0 element, and wherein 0<x≤0.7, 0<y≤0.7, and 0<β≤0.1. Such materials may provide satisfactory, improved, or excellent electrochemical performance at relatively low cost, and without the need for fluorination.