Composite Silicon-LTO Anode Structure for Fast-Charging Stability
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving high capacity, high energy density, and fast charging characteristics, particularly due to volume expansion issues with silicon-based anode materials.
Innovation Solution
A composite anode active material comprising lithium titanium oxide, silicon, and crystalline carbon, which is manufactured through a process involving mixing, spray-drying, and surface modification to form a porous structure with a carbon coating, enhancing electrical conductivity and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as anode material to improve energy density, then theoretical capacity increases to approximately 3572 mAh/g, but volume expansion occurs during charging and discharging
Solution Approach 1:
The silicon-containing material is encapsulated within a porous core structure formed by graphite and crystalline carbon particles. This nested configuration allows the silicon to expand and contract within the confined porous space without causing overall particle disintegration, effectively nesting the high-capacity but unstable silicon inside a stable carbon matrix.
Solution Approach 2:
The invention creates a composite anode material consisting of silicon-containing material, graphite, and crystalline carbon particles. This composite structure combines the high theoretical capacity of silicon with the volume stability and conductivity of graphite and crystalline carbon, achieving both high energy density and structural stability.
2Stability of the object's composition
If graphite is used as anode material to ensure structural stability, then reversible capacity is limited to about 350 mAh/g, but energy density cannot be improved
Solution Approach 1:
The invention merges graphite particles with crystalline carbon particles and silicon-containing material to create a composite anode. This combination allows the structure to maintain the stability of graphite while incorporating the high capacity of silicon, achieving both structural integrity and enhanced reversible capacity.
Solution Approach 2:
The crystalline carbon particles are distributed throughout the porous core structure, providing localized regions of enhanced conductivity and structural support. This local reinforcement allows the overall particle to achieve higher capacity while maintaining stability through strategically placed high-performance regions.
3Stability of the object's composition
If silicon and graphite are compounded to alleviate volume change, then volume stability improves, but fast charging characteristics are not sufficiently improved
Solution Approach 1:
The porous core structure formed by graphite and crystalline carbon particles provides interconnected void spaces that facilitate rapid lithium ion diffusion. This porous architecture reduces the diffusion path length and increases the number of accessible sites for lithium insertion, significantly improving fast charging characteristics while maintaining volume stability.
Solution Approach 2:
The invention introduces a porous three-dimensional structure that adds a spatial dimension for lithium ion transport. The interconnected pores create multiple diffusion pathways and reduce transport resistance, enabling faster charging rates compared to dense composite structures.
4Quantity of substance
If commercial active materials are developed to exhibit performance close to theoretical capacity with graphite, then material limit is reached, but further capacity improvement becomes difficult
Solution Approach 1:
The invention creates a novel composite anode material combining silicon-containing material with graphite and crystalline carbon, breaking beyond the limitations of conventional graphite-based materials. This composite approach enables reversible capacity significantly exceeding the theoretical limit of graphite while maintaining structural stability.
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 composite material improves energy density, fast charging capabilities, and mechanical strength, resulting in a lithium secondary battery with high capacity and extended lifespan.
Implementation Method 1
during charging, lithium ions in the lattice of lithium cobalt oxide move into the graphite through the electrolyte, and during discharging, lithium having been inserted into the graphite moves back into the lattice of the lithium cobalt oxide
Implementation Method 2
enhancing electrical conductivity and mechanical stability
Implementation Method 3
spray-drying the dispersion to prepare a porous lithium titanium oxide-silicon-crystalline carbon composite
Data Source
AI summary
The present invention relates to an anode active material including a composite of lithium titanium oxide (LTO), a silicon-containing material and crystalline carbon, a method for manufacturing the same, and a lithium secondary battery including the same. The composite according to the present invention satisfies high capacity, high energy density and high lifespan stability, improves fast charging characteristics, and also improves mechanical strength, so a lithium secondary battery using the composite as an anode active material can be usefully used for a next-generation electric vehicle, energy storage systems, etc.