Porous Silicon Oxide Anode Composite for Battery Swelling Control
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Solution Overview
Problem
Conventional lithium secondary batteries face challenges with graphite as a negative electrode active material due to its low capacity per unit mass and rapid deterioration caused by volume expansion and contraction during lithium intercalation, leading to reduced lifetime and efficiency.
Innovation Solution
A silicon oxide composite negative electrode active material is developed, incorporating silicon oxide (SiOx) and magnesium silicate with controlled pore sizes (50-300 nm) and a carbon-containing coating layer, which buffers volume expansion and contraction, enhancing mechanical strength and lithium ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a high capacity negative electrode active material, then discharge capacity is improved (4,200 mAh/g), but lifetime characteristics deteriorate rapidly due to volume expansion reaching about 400% when Li ions are intercalated
Solution Approach 1:
The patent utilizes a porous silicon oxide composite structure where the porous framework provides void space to accommodate the volume expansion of silicon during lithium intercalation. The pores act as buffers that absorb expansion stress, preventing structural degradation and maintaining electrode integrity over multiple charge-discharge cycles, thus improving lifetime characteristics while preserving high discharge capacity.
Solution Approach 2:
The patent employs a composite material system consisting of silicon oxide combined with conductive carbon materials and bound rubber. This composite structure synergistically combines the high capacity of silicon with the structural stability of carbon and the flexibility of rubber, creating a material that maintains mechanical integrity during volume changes while enabling efficient lithium ion transport and electrical conductivity.
2Reliability
If graphite is used as a negative electrode active material, then structural stability is maintained, but capacity per unit mass is limited to 372 mAh/g
Solution Approach 1:
The patent creates a composite material that combines silicon oxide (providing high capacity) with conductive carbon materials and bound rubber (providing structural stability). This composite approach allows the electrode to achieve both high capacity and structural stability, overcoming the fundamental limitation of graphite by incorporating materials with complementary properties in a synergistic framework.
Solution Approach 2:
The patent applies different materials with specific local functions: silicon oxide in the core provides high lithium ion capacity, while the surrounding carbon matrix provides structural stability and conductivity, and the bound rubber layer provides flexibility and stress relief. This local differentiation of material properties allows each component to optimize its specific function while contributing to overall electrode performance.
3Quantity of substance
If metal materials such as Si, Sn, Al, Sb are used for alloying or non-alloying reaction with Li, then high capacity is achieved compared to graphite, but large volume expansion or contraction causes micronization and loss of conduction path
Solution Approach 1:
The patent utilizes a flexible bound rubber layer that surrounds the silicon oxide particles. This flexible shell can dynamically expand and contract with the underlying silicon oxide during lithium intercalation, maintaining continuous physical contact and preserving the conduction path. The rubber's elasticity prevents the formation of micropores and discontinuities that would otherwise break the conductive network.
Solution Approach 2:
The conductive carbon material and bound rubber act as intermediary phases between the silicon oxide particles and the electrode current collector. These intermediaries maintain continuous electrical contact during volume changes, bridging any gaps that form due to expansion and contraction, thereby preserving the conduction path and preventing isolation of active material particles.
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 silicon oxide composite effectively prevents rapid deterioration, improves lithium secondary battery lifetime and efficiency by managing volume changes and maintaining mechanical integrity, while also enhancing charging and discharging performance.
Implementation Method 1
the pores disposed inside the silicon oxide composite play roles of solving a swelling problem and preventing rapid deterioration degree of lifetime due to expansion and contraction by playing a role of buffering expansion in the charging process
Implementation Method 2
Si has been known to be the most appropriate material as a high capacity negative electrode active material in aspects of discharge capacity (4,200 mAh/g) and discharge voltage (0.4 V), Si has shown a rapid drop in lifetime characteristics as degeneration of the active material is generated by expansion of a large volume reaching about 400 % caused when Li ions are intercalated (charged) into the material
Data Source
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AI summary
The present disclosure relates to a negative electrode active material for non-aqueous electrolyte secondary battery, and a negative electrode active material for non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure comprises a silicon oxide composite comprising silicon, silicon oxide (SiOx, 0<x≤2) and magnesium silicate, and including pores with a size of 50 to 300 nm therein. The negative electrode active material for non-aqueous electrolyte secondary battery comprising the silicon oxide composite according to the present disclosure solves a swelling problem by allowing the pores inside the silicon oxide composite to play a role of buffering expansion in the charging process, efficiently controls volume expansion by allowing stress caused by expansion and contraction generated during charging or discharging to be concentrated in the pores inside the silicon oxide composite, and can improve lifetime characteristics of the lithium secondary battery accordingly.