Lithiated Silicon-Carbon Composite Anode for Lithium Batteries
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Solution Overview
Problem
Silicon-based anode materials in lithium batteries face high irreversible losses and poor cycle stability due to volume changes and foreign elements, limiting their capacity and reversibility, while existing composite materials do not meet the requirements of low initial losses, high capacity, and commercial viability.
Innovation Solution
A composite material composed of tribochemically or thermally produced reaction products of graphitic or graphene-like carbon with elemental silicon and lithium, with an empirical formula SixC10-xLiz, is produced through a milling process under inert conditions, followed by stabilization to minimize reactions with air and water, and optionally tempered to form lithium silicides, enhancing stability and electrochemical potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to achieve high lithium absorption capacity, then capacity increases, but volume changes cause pulverization and poor reversibility
Solution Approach 1:
The patent embeds silicon particles within a carbon matrix structure, creating a nested configuration where silicon is contained within carbon. This nesting approach allows silicon to expand and contract during lithium cycling while being constrained by the carbon matrix, preventing pulverization and maintaining structural integrity for high capacity and good reversibility
Solution Approach 2:
The patent creates a composite material consisting of silicon particles dispersed in a carbon matrix. This composite structure combines the high lithium absorption capacity of silicon with the structural stability and conductivity of carbon, resolving the contradiction between achieving high capacity and maintaining cycle stability
2Ease of manufacture
If foreign elements are present in silicon to improve manufacturability, then processing becomes easier, but irreversible losses increase due to reactions with lithium
Solution Approach 1:
The patent removes foreign elements such as oxygen, hydrogen, and inorganic carbon from the silicon material through purification processes. By extracting these harmful impurities before composite formation, the patent prevents irreversible reactions with lithium while maintaining the ease of manufacturing silicon-based anodes
3Quantity of substance
If particle size is reduced to submicron range to improve electrochemical properties, then capacity increases, but manufacturing complexity increases
Solution Approach 1:
The patent employs self-ball-milling techniques where the milling media and materials mutually process each other during mixing. This self-service approach automatically reduces particle sizes to the submicron range and ensures uniform distribution of silicon in the carbon matrix without requiring additional complex size-reduction equipment or multiple processing steps
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 achieves low irreversible initial losses, high capacity, and improved cycle stability, with electrochemical rest potential below 2 V, making it suitable for high-capacity anode materials in lithium batteries with enhanced thermal stability and safety.
Implementation Method 1
The invention relates to a composite material consisting of the tribochemically/thermally produced reaction product of graphitic or graphene-like carbon with elemental silicon and elemental lithium
Implementation Method 2
The uncoated lithiated or partially lithiated composites are subjected to a tempering step at temperatures between 100 and 350° C., preferably 150 and 250° C., following the mechanochemical reaction
Data Source
AI summary
The invention relates to composite materials of general composition SixC10-xLi in which x can be any value from 1 - 9 and z = a (4,4x + 1/6 (10-x)) and a = any value from 0.1 - 1, which can be used as highly capacitive anode materials for galvanic cells with non-aqueous electrolytes, and to a method for the production thereof.