Silicon Negative Electrode Coating for Battery Gas Suppression
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries using silicon-based active materials face challenges with high irreversible capacity, poor cycle properties, and significant gas generation, which affect safety and reliability.
Innovation Solution
A negative electrode material is developed by coating silicon-based active material particles with a film of an organosilicon compound containing a perfluoropolyether group, optimizing the mass ratio to enhance capacity, charge/discharge efficiency, and suppress gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used as negative electrode material, then capacity is improved, but irreversible capacity and gas generation increase
Solution Approach 1:
A coating layer comprising fluorinated cyclic carbonate and chain carbonate is introduced as an intermediary between the silicon-based active material and the electrolyte. This coating layer acts as a mediator that suppresses the reaction between water in the battery and LiPF6 in the electrolyte, preventing HF generation and subsequent gas evolution, while still allowing the silicon-based material to function as a high-capacity negative electrode
Solution Approach 2:
The negative electrode is constructed as a composite material system combining silicon-based active material particles with a dual-component coating layer (fluorinated cyclic carbonate and chain carbonate). This composite structure leverages the high capacity of silicon while the coating components work synergistically to suppress harmful reactions and gas generation
2Quantity of substance
If silicon-based active material is used as negative electrode material, then capacity is improved, but cycle property deteriorates
Solution Approach 1:
The coating layer of fluorinated cyclic carbonate and chain carbonate serves as a protective intermediary that stabilizes the interface between the silicon-based active material and the electrolyte. By suppressing parasitic reactions and preventing HF generation, the coating maintains electrode integrity over repeated charge/discharge cycles, thereby improving cycle property
Solution Approach 2:
The invention changes the chemical composition parameters of the electrode surface by introducing fluorinated cyclic carbonate and chain carbonate components. This parameter change in surface chemistry creates a more stable interface that resists degradation during cycling, improving the reliability and cycle life of the battery
3Object-generated harmful factors
If surface of particles is modified to suppress gas generation, then safety is improved, but capacity and charge/discharge efficiency deteriorate
Solution Approach 1:
The coating is applied locally on the surface of silicon-based active material particles rather than uniformly throughout the electrode. This local modification suppresses gas generation at the particle surface where reactions occur, while the bulk silicon material retains its high capacity properties. The coating thickness and composition are optimized to maintain electrical conductivity and lithium ion transport
Solution Approach 2:
The surface parameters of the silicon particles are changed by coating with fluorinated cyclic carbonate and chain carbonate, which have specific molecular structures that suppress gas-generating reactions. The coating parameters (composition ratio, thickness) are optimized to achieve the right balance between gas suppression and maintaining capacity
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 solution results in a non-aqueous electrolyte secondary battery with improved capacity, initial charge/discharge efficiency, and reduced gas generation, ensuring higher safety and reliability, while being suitable for industrial-scale production.
Implementation Method 1
it is considered effective to modify a surface of particles to suppress the reaction according to the chemical reaction formula (b) to suppress gas generation inside a cell
Implementation Method 2
the HF gas reacts with SiO 2 that is contained in the silicon-based active material according to the chemical reaction formula (b) to generate a gas
Data Source
AI summary
The present invention provides a negative electrode material for a non-aqueous electrolyte secondary battery that includes particles of a silicon-based active material, the particles of a silicon-based active material being coated with a film of an organosilicon compound that contains a perfluoropolyether group, and a non-aqueous electrolyte secondary battery therewith. As a result, there is provided a negative electrode material for a non-aqueous electrolyte secondary battery that is high in capacity, excellent in initial charge/discharge efficiency and cycle characteristics and high in safety and reliability, and a non-aqueous electrolyte secondary battery that uses the negative electrode material.