SiOx-CMC-CNT Anode Composite for Lithium Battery
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Solution Overview
Problem
Lithium secondary batteries using carbon-based anode materials like graphite face limitations in capacity and cycle life due to volume changes and poor distribution of conductive materials, while surface-treating carbon nanotubes on silicon oxide (SiO) does not effectively improve attachment and battery performance.
Innovation Solution
A composite anode active material of SiOx-carboxylmethyl cellulose (CMC)-carbon nanotube (CNT) is developed, where CNT is bonded to SiOx through CMC, with specific weight ratios to ensure secure attachment and dispersion, enhancing the anode's life characteristics by reducing volume expansion and improving cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-based anode active material (Si, Sn, oxide, alloy) is used to achieve higher charge/discharge capacity than carbon materials, then capacity is improved, but volume change during charging/discharging causes cracks and micronization, deteriorating capacity and cycle life
Solution Approach 1:
The patent uses a composite structure consisting of SiOx core particles coated with a carbon-containing layer. This composite design combines the high capacity advantage of silicon-based materials with the structural stability and volume tolerance of carbon materials, resolving the contradiction between achieving high capacity and maintaining cycle life through repeated charging/discharging cycles.
2Reliability
If SiO is mixed with graphite and conductive material is dispersed to improve life characteristic, then cycle performance is improved, but conductive material is not uniformly distributed on SiO surface due to poor dispersity, greatly deteriorating cycle performance
Solution Approach 1:
The conductive material is pre-dispersed within the carbon-containing layer before the layer is formed on the SiOx particles. This preliminary dispersion action ensures uniform distribution of conductive material throughout the coating layer, avoiding aggregation and ensuring consistent electrical conductivity across all particles, thereby improving cycle performance.
3Duration of action of stationary object
If carbon nanotube is pre-treated on SiO surface to improve life characteristic, then battery life is improved, but CNT has not been well-attached to SiO surface
Solution Approach 1:
The carbon-containing layer acts as an intermediary between the SiOx particles and the carbon nanotubes. The nanotubes are dispersed and embedded within this intermediate carbon layer, which provides strong adhesion to both the SiOx core and the nanotube structure. This intermediary layer ensures well-attached nanotubes that remain firmly bound during charging/discharging cycles, improving battery life through enhanced structural integrity.
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 SiOx-CMC-CNT composite significantly enhances battery capacity and life characteristics compared to SiO surface-treated with only carbon nanotubes, achieving improved cycle life and capacity retention.
Implementation Method 1
CNT is bonded to SiOx through CMC
Implementation Method 2
enhancing the anode's life characteristics by reducing volume expansion
Data Source
AI summary
The present disclosure relates to an anode active material for a lithium secondary battery, a lithium secondary battery comprising the anode active material, and a method of preparing the anode active material. One embodiment of the present disclosure provides an anode active material for a lithium secondary battery, comprising a composite of SiOx-carboxylmethyl cellulose (CMC)-carbon nanotube (CNT) in which CNT is bonded to SiOx (0<x≤1) through CMC; and a carbon-based material. Also, another embodiment of the present disclosure provides a method of preparing an anode active material for a lithium secondary battery, comprising bringing SiOx (0<x≤1) into surface-treatment with carbon nanotube (CNT) and carboxylmethyl cellulose (CMC) to form a composite of SiOx-CMC-CNT; and mixing the composite of SiOx-CMC-CNT with a carbon-based material. The anode active material and the lithium secondary battery of the present disclosure provide enhanced battery capacity, as well as improved life characteristics as compared with those having SiO surface-treated with only carbon nanotube.