Pre-lithiation Composite Layer for Silicon Anode Capacity
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Solution Overview
Problem
Existing methods for pre-lithiating negative electrodes in secondary batteries face challenges such as high production costs, safety risks due to high temperatures, and uneven irreversible capacity, particularly when using silicon-based materials, which lead to reduced battery capacity and cycle life.
Innovation Solution
A method involving the dispersion of lithium metal powder, an inorganic material powder, and a binder in a solvent to form a lithium metal-inorganic composite layer on the negative electrode, which is then applied to improve initial irreversibility and safety by simplifying the process and reducing the risk of side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is used to increase capacity, then energy density is improved, but initial irreversible capacity increases rapidly reducing battery cycle life
Solution Approach 1:
The patent applies pre-lithiation by forming a lithium metal-inorganic composite layer on the negative electrode before battery assembly. This preliminary action compensates for the initial irreversible capacity loss that occurs during first charging, ensuring that sufficient lithium remains for subsequent reversible cycles and extending battery cycle life while maintaining high capacity from silicon-based materials.
Solution Approach 2:
The patent uses a composite structure combining lithium metal with inorganic materials (such as oxides or nitrides) to form the pre-lithiation layer. This composite approach provides both the lithium source needed to compensate for irreversible capacity and the structural stability required to maintain electrode integrity during cycling, thereby extending battery life.
2Duration of action of stationary object
If conventional pre-lithiation methods are used, then initial irreversible capacity is reduced, but production cost increases and safety risks arise from high temperature processing
Solution Approach 1:
The patent replaces conventional high-temperature thermal processing methods with a low-temperature coating and drying process. The lithium metal-inorganic composite slurry is applied to the negative electrode and then dried at relatively low temperatures, eliminating the safety risks and high energy consumption associated with high-temperature pre-lithiation methods while achieving the same effect of reducing initial irreversible capacity.
Solution Approach 2:
The patent introduces a slurry medium containing lithium metal powder, inorganic material powder, and binder as an intermediary carrier. This slurry allows for uniform distribution of lithium metal on the negative electrode surface at low temperatures, avoiding the need for direct high-temperature contact between lithium metal and the electrode, thereby improving safety and reducing production costs.
3Reliability
If graphite is used as negative electrode active material to ensure safety and long life, then reliability is improved, but energy density per unit volume decreases
Solution Approach 1:
The patent merges the advantages of both graphite and silicon-based materials by combining a silicon-based negative electrode active material (for high capacity) with a pre-lithiation layer (to compensate for irreversible capacity loss). This combination achieves high energy density while maintaining reliability and long cycle life, effectively merging the benefits of different material systems.
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 enhances the initial irreversibility and charge/discharge efficiency of the negative electrode, improves safety by converting lithium metal to an inorganic form, and maintains battery performance over cycles, with the lithium metal-inorganic composite layer acting as a protective layer.
Implementation Method 1
dispersing a lithium metal powder, an inorganic material powder and a binder in a solvent to prepare a mixed solution
Implementation Method 2
converting lithium metal to an inorganic form
Data Source
AI summary
A method of pre-lithiating a negative electrode for a secondary battery, including: dispersing a lithium metal powder, an inorganic material powder and a binder in a solvent to prepare a mixed solution; and applying the mixed solution to the negative electrode to form a lithium metal-inorganic composite layer on the negative electrode, thereby forming the pre-lithiated negative electrode. Also, a method for pre-lithiating a negative electrode having a high capacity by a simple process. Further, a negative electrode for a secondary battery manufactured through the pre-lithiation method provided in the present invention has an improved initial irreversibility, and secondary batteries manufactured using such a negative electrode for a secondary battery have excellent charge/discharge efficiency.