Silicon Anode Ceramic Coating to Suppress Gas and Capacity Loss
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Solution Overview
Problem
Silicon-based negative electrodes in lithium secondary batteries experience rapid volume expansion during charging, leading to disconnection of the conductive path, surface degradation, and reduced battery capacity and life due to gas generation and uneven lithium ion charging.
Innovation Solution
A negative electrode for lithium secondary batteries is developed, featuring a silicon-based negative electrode active material layer with a ceramic layer on top. The ceramic layer, composed of ceramic and a binder with BaTiO3 in a specific weight ratio, has a thickness between 0.5 μm and 10 μm, effectively suppressing gas generation and improving cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then battery capacity increases, but volume expansion occurs during charging causing conductive path disconnection
Solution Approach 1:
A ceramic layer is introduced as an intermediary between the silicon-based active material and the electrolyte. This ceramic layer acts as a mediator that suppresses excessive gas generation while allowing controlled lithium ion transport, thereby preventing conductive path disconnection caused by volume expansion during charging.
Solution Approach 2:
The negative electrode is constructed as a composite structure combining silicon-based active material with a ceramic coating layer. This composite material approach leverages the high capacity of silicon while the ceramic component provides structural stability and controls gas generation, resolving the contradiction between capacity and conductive path stability.
2Quantity of substance
If silicon-based active material is used, then discharge capacity increases, but surface degradation accelerates due to non-uniform lithium ion charging
Solution Approach 1:
The ceramic layer serves as an intermediary protective barrier on the silicon-based active material surface. It promotes uniform lithium ion distribution during charging by controlling ion transport, thereby preventing localized surface degradation while maintaining high discharge capacity.
3Quantity of substance
If silicon-based compound is used, then capacity increases, but gas generation occurs leading to electrode separation and increased resistance
Solution Approach 1:
The ceramic layer converts the harmful gas generation effect into a beneficial controlled process. It allows minimal gas generation that helps form a stable solid electrolyte interface (SEI) layer, while suppressing excessive gas that would cause electrode separation. The ceramic transforms the harmful volume expansion and gas generation into a controlled mechanism that stabilizes the electrode structure.
Solution Approach 2:
The ceramic layer changes the physical and chemical parameters at the active material surface, including gas permeability and surface energy. These parameter changes suppress excessive gas generation while maintaining necessary ion transport, thereby preventing electrode separation and resistance increase.
4Duration of action of stationary object
If ceramic layer is added to suppress gas generation, then battery life improves, but electrode structure complexity increases
Solution Approach 1:
A thin ceramic film is applied to the silicon-based active material surface. This thin film approach provides the necessary protective function to suppress gas generation and improve battery life, while minimizing the added structural complexity and maintaining electrode flexibility.
Data Source
AI summary
The present disclosure relates to a negative electrode for a lithium secondary battery, a method for manufacturing the negative electrode, and the lithium secondary battery including the negative electrode. The negative electrode can include a negative electrode current collector layer, a silicon-based negative electrode active material layer provided on at least one surface of the negative electrode current collector layer, and a ceramic layer provided on a surface of the silicon-based negative electrode active material layer opposite to a surface of the negative electrode active material layer facing the negative electrode current collector layer. The ceramic layer can include a ceramic layer composition or a dried product thereof, and the ceramic layer composition can include ceramic and a binder. BaTiO3 can be included in an amount of 10 parts by weight or more and 50 parts by weight or less based on 100 parts by weight of the ceramic.