Pre-lithiated Silicon Oxide Negative Electrode Tab Protection
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Solution Overview
Problem
Lithium secondary batteries face challenges with high irreversibility and reduced capacity due to the formation of the solid electrolyte interface (SEI) layer, particularly with silicon-based materials, which leads to electrode structure damage and increased resistance, and the pre-lithiation process generates lithium by-products on uncoated areas, hindering the connection of negative electrode tabs to leads during manufacturing.
Innovation Solution
A secondary battery design featuring a pre-lithiated negative electrode current collector with an inorganic substance layer on the negative electrode tab, preventing lithium by-product formation on uncoated areas and facilitating easy connection to the lead, while using a silicon oxide-based material like SiO with a carbon-based material to minimize irreversibility and enhance cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based material is used as negative electrode active material to achieve high capacity, then the battery capacity is improved, but the volumetric expansion ratio increases by 300% or more with increasing cycle count, causing electrode structure damage and increased resistance
Solution Approach 1:
The patent uses a composite negative electrode active material consisting of silicon oxide-based material (such as SiOx where 0.5 ≤ x ≤ 1.2) combined with carbon-based material. The silicon oxide provides high capacity while the carbon matrix constrains volumetric expansion, reducing structure damage and maintaining electrode stability during cycling.
Solution Approach 2:
The patent changes the oxidation state of silicon from metallic silicon (Si) to silicon oxide (SiOx), which fundamentally alters the volumetric expansion behavior. The silicon oxide-based material exhibits significantly lower volumetric expansion ratio compared to pure silicon, thereby improving electrode structure stability while maintaining high capacity.
2Duration of action of stationary object
If pre-lithiation is performed by feeding negative electrode into solution containing lithium source to decrease initial irreversibility, then lifespan is improved, but lithium by-products are generated on uncoated areas, making it impossible to weld negative electrode tab to lead
Solution Approach 1:
The patent applies different surface treatments to different regions of the negative electrode. The active material-coated area undergoes pre-lithiation to reduce initial irreversibility, while the uncoated tab area is protected from pre-lithiation by maintaining its original surface quality, ensuring weldability to the lead.
Solution Approach 2:
The negative electrode is divided into functionally distinct regions: the active material-coated area for electrochemical activity and pre-lithiation, and the uncoated tab area for electrical connection and welding. This segmentation allows each region to be optimized for its specific function without compromising the other.
3Duration of action of stationary object
If silicon oxide-based material is used to reduce volumetric expansion ratio, then cycle characteristics are improved, but SEI layer formation during charging and high frequency of initial irreversibility to Li2O due to oxygen in active material occur
Solution Approach 1:
The patent performs pre-lithiation treatment before battery assembly by feeding the negative electrode into a solution containing lithium source and applying current. This preliminary action converts oxygen in the silicon oxide-based material into lithium oxide, reducing initial irreversibility during subsequent charging cycles while maintaining the low volumetric expansion benefits of silicon oxide.
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
This approach enhances the lifespan and rate characteristics of the battery by reducing irreversibility and improving production efficiency through the use of an inorganic substance layer on the negative electrode tab, allowing for effective pre-lithiation of the active material and secure electrical connections.
Implementation Method 1
pre-lithiation reaction on a negative electrode current collector coated with a negative electrode active material
Implementation Method 2
a volumetric expansion ratio thereof is 300% or more with increasing cycle count
Implementation Method 3
research into a method to change oxygen, which is present in a silicon oxide-based material, causing high irreversible capacity into a lithium oxide through pre-lithiation of the silicon oxide-based material
Data Source
AI summary
Disclosed are a secondary battery comprising a negative electrode composed of two or more negative electrode plates and a method of manufacturing the secondary battery, wherein each of the negative electrode plates includes a lithium by-product layer formed through pre-lithiation reaction on a negative electrode current collector coated with a negative electrode active material, wherein an inorganic substance layer is formed on a negative electrode tab that is extended from an end at one side of the negative electrode current collector and is composed of an active material-non-coated portion not coated with the negative electrode active material, and negative electrode tabs of the negative electrode plates are electrically connected with one negative electrode lead to form a negative electrode terminal.