Li5FeO4 Cathode Additive Coating for Air-Stable Prelithiation
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Solution Overview
Problem
Existing lithium secondary batteries face challenges with metal and metal oxide-based anode active materials due to high volume change during charging and discharging, irreversible reactions, and low atmospheric stability of sacrificial positive electrode materials like Li5FeO4, limiting capacity and safety.
Innovation Solution
A manufacturing method for a cathode additive involving the formation of a double coating layer on Li5FeO4-based lithium transition metal oxide particles, comprising a carbon nanotube-containing layer and a lithium difluoro(oxalato)borate-containing layer, enhancing electrical conductivity and air stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li5FeO4 is used as sacrificial positive electrode material, then irreversible capacity is improved, but air stability deteriorates
Solution Approach 1:
A coating layer comprising carbon nanotubes and lithium difluoro(oxalato)borate is introduced as an intermediary between Li5FeO4 and the atmosphere. This coating layer preserves the high irreversible capacity of Li5FeO4 while providing protection against atmospheric degradation, effectively mediating between the conflicting requirements of high irreversible capacity and air stability.
2Quantity of substance
If metal and metal oxide-based anode active material is applied, then capacity is improved, but volume change increases
Solution Approach 1:
The invention changes the physical and chemical parameters of the anode active material by applying a coating layer of carbon nanotubes and lithium difluoro(oxalato)borate. This coating modifies the material's properties to reduce volume change during charging and discharging while preserving the high capacity benefits of metal and metal oxide-based materials.
3Quantity of substance
If metal and metal oxide-based anode active material is applied, then capacity is improved, but irreversible reaction increases
Solution Approach 1:
The coating layer comprising carbon nanotubes and lithium difluoro(oxalato)borate serves as an intermediary that reduces irreversible reactions between the metal/metal oxide anode active material and the electrolyte. This protective layer allows high capacity utilization while minimizing energy loss through unwanted side reactions.
4Quantity of substance
If cathode material is coated to compensate lithium loss, then lithium loss is compensated, but energy density decreases
Solution Approach 1:
The invention changes the parameters of the cathode additive by using Li5FeO4 with a coating layer, which provides high irreversible capacity (desorption of lithium) without requiring large amounts of additional cathode material. This approach compensates for lithium loss while maintaining energy density, unlike conventional methods that require adding significant amounts of low-capacity cathode material.
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 cathode additive improves electrical conductivity, irreversible capacity, and air stability, thereby increasing battery capacity and safety by compensating for lithium loss and reducing gas generation.
Implementation Method 1
enhancing electrical conductivity
Implementation Method 2
enhancing electrical conductivity and air stability
Implementation Method 3
a material suitable for prelithiation of the battery in the cathode needs to have an irreversible property in which lithium is desorbed at least twice as much as that of a conventional cathode material during initial charge
Data Source
AI summary
The method includes mixing and heat-treating carbon nanotubes, a water-soluble polymer dispersant, and an iron (Fe) precursor to form an iron oxide-carbon precursor; mixing and calcining a lithium precursor and the iron oxide-carbon precursor at a temperature of 500° C. or higher to form lithium-iron oxide particles; and heat-treating a mixture containing the lithium-iron oxide particles and a lithium difluoro(oxalato)borate under an oxygen-containing gas atmosphere at a temperature of less than 300° C. to form a lithium-iron oxide coated with a lithium difluoro(oxalato)borate-containing layer.