Prelithiated Silicon Anode Material for First-Cycle Efficiency
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Solution Overview
Problem
Silicon-based anode materials for lithium secondary batteries face challenges due to high irreversible capacity in the first cycle, leading to low initial efficiency and stability issues, particularly with the prelithiation method which involves high costs and safety concerns, and results in poor atmospheric and moisture stability of lithium silicide.
Innovation Solution
A prelithiation method for silicon oxide-based anode materials involving immersion in a lithium-hydrocarbon molecule complex solution followed by washing, drying, and heat treatment in an inert gas atmosphere at 400° C. to 800° C., which enhances uniform lithiation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based anode materials are used to increase capacity, then energy density is improved, but initial efficiency deteriorates due to high irreversible capacity in the first cycle
Solution Approach 1:
The patent applies preliminary action by pre-inserting lithium into the silicon-based anode material before the battery's first charge-discharge cycle. This is achieved through contact with a lithium metal anode during electrode assembly, creating a prelithiated anode that reduces irreversible capacity loss in the first cycle and improves initial efficiency while maintaining high energy density
2Quantity of substance
If lithium is inserted into SiOx-based material to form lithium silicide, then capacity is improved, but atmospheric and moisture stability deteriorates
Solution Approach 1:
The patent uses a lithium metal anode as an intermediary to transfer lithium to the SiOx-based material. This indirect lithium insertion method allows controlled formation of lithium silicide while maintaining stability, as the lithium metal anode acts as a buffer that regulates the lithium transfer process and prevents direct exposure of the SiOx material to harsh conditions during slurry preparation
3Reliability
If direct contact with lithium metal is used for prelithiation, then initial efficiency is improved, but safety and cost deteriorate
Solution Approach 1:
The patent merges the function of the lithium metal anode with the prelithiation function by using the lithium metal anode as both the active material for lithium supply and the prelithiation source. This integration eliminates the need for separate prelithiation steps, reduces safety risks associated with handling lithium metal, and lowers costs by simplifying the electrode assembly process
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 method achieves high initial coulombic efficiency and long lifespan for secondary batteries by ensuring safe and uniform lithiation, while also improving atmospheric and moisture stability of the active material.
Implementation Method 1
a spontaneous charge transfer reaction between a lithium-hydrocarbon molecule complex with an oxidation-reduction potential of 0.5 V (vs Li/Li+) or less and a silicon oxide-based (SiOx, 0
Implementation Method 2
step S3 of performing a heat treatment on the powder at a temperature of 400° C. to 800° C. in an inert gas atmosphere
Data Source
AI summary
Provided are a prelithiation method of a silicon-based active material, the prelithiation method including step S1 of immersing the silicon-based active material in a prelithiation solution including an organic solvent and a lithium-hydrocarbon molecule complex, step S2 of obtaining a powder by washing the silicon-based active material with the organic solvent and drying the silicon-based active material, and step S3 of performing a heat treatment on the powder at a temperature of 400° C. to 800° C. in an inert gas atmosphere, and a silicon-based active material prelithiated by the method.