Silicon Clathrate Electrode Etching for Low-Pressure Li-Ion Batteries
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Solution Overview
Problem
The challenge is to develop a method for manufacturing a silicon clathrate electrode active material that can selectively remove type I silicon clathrate, which undergoes significant expansion and contraction during battery charging-discharging, to minimize pressure increases in lithium-ion batteries.
Innovation Solution
A method involving contacting silicon clathrate particles containing both type I and type II silicon clathrates with a hydrogen fluoride solution, where the ratio of hydrogen fluoride to silicon clathrate particles is optimized to selectively remove type I silicon clathrate, using a mixed solvent of water and an organic solvent to suppress by-product formation and bubble generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon electrode active material is used to achieve high energy densification, then battery capacity is improved, but expansion during charging increases causing pressure issues
Solution Approach 1:
The patent changes the crystal structure parameter of silicon from type I to type II clathrate structure. Type II silicon clathrate has a different atomic arrangement with smaller voids and more efficient lithium occlusion sites, which fundamentally alters the expansion behavior during charging while maintaining high capacity
Solution Approach 2:
The patent creates local structural differences by forming type II clathrate structures with specific cage configurations that locally accommodate lithium ions more efficiently. This local structural optimization reduces overall expansion while maintaining the high capacity benefit of silicon
2Ease of manufacture
If type I silicon clathrate is present in the mixture, then manufacturing is simpler, but expansion and contraction during charging-discharging increases
Solution Approach 1:
The patent selectively removes type I silicon clathrate from the mixture containing both type I and type II clathrates. This extraction is achieved through controlled etching processes that exploit the different chemical reactivity and structural characteristics of type I versus type II clathrate structures, leaving behind the more stable type II structure
Solution Approach 2:
The patent employs a dynamic selective etching process where the etching conditions (reagent type, concentration, temperature, time) are optimized to dynamically differentiate between type I and type II clathrates. The process continuously adjusts to maintain selectivity, removing type I while preserving type II structures
3Manufacturing precision
If hydrogen fluoride solution is used to remove type I silicon clathrate, then type I removal is achieved, but by-product formation and bubble generation occur
Solution Approach 1:
The patent optimizes multiple parameters of the hydrogen fluoride solution including concentration, temperature, and composition ratios to maximize selective removal of type I clathrate while minimizing harmful by-products. Specific parameter ranges are established to control the etching reaction and reduce unwanted side effects
Solution Approach 2:
The patent introduces an intermediary substance or modified hydrogen fluoride solution composition that mediates the etching process. This intermediary facilitates the selective removal of type I clathrate while reducing direct harmful interactions that produce bubbles and unwanted by-products, acting as a buffer or catalyst in the reaction
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
This approach effectively removes type I silicon clathrate, reducing expansion and contraction-related pressure issues during battery operation, thereby enhancing the stability and performance of lithium-ion batteries.
Implementation Method 1
contacting the silicon clathrate particle with a hydrogen fluoride solution to remove at least a portion of the type I silicon clathrate
Data Source
AI summary
The present disclosure provides a method for manufacturing a silicon clathrate positive electrode active material capable of removing at least a portion of a type I silicon clathrate, and a method for manufacturing a lithium-ion battery comprising manufacturing such a silicon clathrate electrode active material. Disclosed methods of making silicon clathrate electrode active material, comprising the following steps: (a) providing silicon clathrate particle that contain a type I silicon clathrate and a type II silicon clathrate, and (b) contacting the silicon clathrate particle with a hydrofluoric solution to remove at least a portion of the type I silicon clathrate.