Pre-Lithiated Li-Mn Oxide Molten Salt Process for Anode-Free Cathodes
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Solution Overview
Problem
Conventional lithium ion cells face safety issues due to thermal runaway and limited energy density, while anode-free designs lack sufficient lithium replenishment, and existing processes for pre-lithiated LiMn2O4 production are challenging for commercial viability.
Innovation Solution
A molten salt process involving mixing lithium manganese-based oxide with lithium salt and potassium hydroxide, followed by exposure to a reducing agent at controlled temperatures to form pre-lithiated lithium manganese-based oxides, which are then collected, filtered, and dried, eliminating the need for organic solvents and reducing agents like butyllithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium ion cells use organic electrolyte and graphite anode, then the cell can operate, but thermal runaway and fire hazards occur during thermal runaway situations
Solution Approach 1:
The patent removes the organic electrolyte from the battery system and replaces it with a solid-state electrolyte, extracting the harmful component that causes thermal runaway and fire hazards while maintaining the essential ionic conduction function
Solution Approach 2:
The patent creates an inert environment by using solid-state electrolyte materials that are non-flammable and thermally stable, replacing the flammable organic electrolyte atmosphere with a safe solid-state medium that prevents thermal runaway
2Reliability
If thin lithium foil is used as anode to compensate for lithium loss, then lithium replenishment is achieved, but production cost increases due to difficulty and expense of producing thin lithium foils
Solution Approach 1:
The patent removes the thin lithium foil anode from the battery structure, extracting the costly component while using pre-lithiated cathode material to provide the necessary lithium reservoir through solid-state diffusion mechanisms
Solution Approach 2:
The patent replaces expensive thin lithium foils with a more economical pre-lithiated cathode material that provides sufficient lithium content through solid-state diffusion, using a cheaper material to achieve the same functional outcome
3Manufacturing precision
If chemical lithiation process using butyllithium and ether solvent is used to prepare pre-lithiated LiMn2O4, then pre-lithiated product is obtained, but the process becomes extremely challenging for commercial utilization due to high reactivity and flammability
Solution Approach 1:
The patent replaces the chemical lithiation process with a mechanical/physical solid-state diffusion process, substituting chemical reactions involving butyllithium with thermal processing that enables lithium diffusion through solid-state mechanisms, eliminating the need for highly reactive chemicals
Solution Approach 2:
The patent changes the processing parameters from ambient temperature chemical reactions to elevated temperature solid-state diffusion (400-600°C), transforming the reaction mechanism from chemical to physical diffusion while achieving the same pre-lithiation outcome
4Manufacturing precision
If solid-state process using Lil as reducing agent at 460°C is used to prepare pre-lithiated LiMn2O4, then pre-lithiated product is obtained, but by-products deposit onto internal surface of reactor requiring frequent washing and extensive cleaning
Solution Approach 1:
The patent uses a reducing agent (ammonia or hydrocarbon) that converts potential harmful by-products into beneficial nitrogen or hydrocarbon gases that volatilize completely, transforming the cleaning problem into a self-cleaning process where by-products leave no residue
Solution Approach 2:
The patent exploits phase transitions by selecting a reducing agent that converts solid by-products into gaseous products that volatilize at reaction temperatures, using the gas phase to eliminate the need for reactor cleaning by complete volatilization of reaction by-products
5Ease of manufacture
If anode-free design is used to reduce production costs, then production cost decreases, but cycling capacity is insufficient due to lack of lithium to replenish lithium loss
Solution Approach 1:
The patent performs preliminary action by pre-lithiating the cathode material during manufacturing, incorporating excess lithium into the cathode structure in advance to compensate for future lithium loss during cycling, eliminating the need for a separate anode lithium reservoir
Solution Approach 2:
The patent enables the cathode material to serve dual functions: as the active cathode material and as the lithium reservoir, allowing the cathode to self-replenish lithium during cycling through solid-state diffusion from the pre-lithiated structure
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 process produces pre-lithiated lithium manganese-based oxides safely and efficiently, suitable for use in anode-free batteries, enhancing energy density and safety without the need for thin lithium foils, and reducing production costs.
Implementation Method 1
the amount of the lithium salt and the KOH present are in a ratio that results in at least a portion of the lithium salt being in a liquid state at the predetermined temperature
Implementation Method 2
exposing the mixture to a predetermined temperature within the range of 226° C. to 450° C. in the presence of a reducing agent... wherein the reducing agent comprises ammonia (NH3)
Data Source
AI summary
A process of preparing a pre-lithiated lithium manganese-based oxide product for use as a cathode active material in an energy storage device. The process includes mixing together a lithium manganese-based oxide having a spinel crystal structure. a lithium salt, and KOH to form a mixture. This mixture is exposed to a temperature within the range of 226° C. to 450° C. in the presence of a reducing agent to form the pre-lithiated lithium manganese-based oxide product. The reducing agent comprises NH3 and the amount of lithium salt and KOH present in the mixture are in a ratio that results in at least a portion of the lithium salt being in a liquid state at the selected temperature. The KOH is removed from the pre-lithiated lithium manganese-based oxide product and the resulting product collected. An energy storage device using the pre-lithiated lithium manganese-based oxide product as a cathode active material is also provided.