Porous Silicon Anode Material Doping for Crack-Resistant Capacity
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Solution Overview
Problem
Lithium secondary batteries face challenges with silicon-based anode active materials due to volume expansion ratios with carbon, leading to cracks and reduced capacity retention during repeated charging and discharging.
Innovation Solution
Development of silicon-based active material particles doped with metal elements like Mg, with controlled porosity and Si/Me ratios, and optionally coated with carbon, to enhance life-span and initial discharge capacity while suppressing volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then energy density is improved, but volume expansion causes cracks and reduces reliability
Solution Approach 1:
The patent applies porous materials by introducing a controlled pore structure within the silicon-based active material particles. The porosity ranges from 0.1% to 10.0% (preferably 0.5% to 5.0%), providing internal void space that accommodates volume expansion during lithium insertion, thereby preventing particle cracking while maintaining high capacity
Solution Approach 2:
The patent uses composite materials by combining silicon-based active material with metal elements (such as Mg, Li, Al, Ca, Fe, Ti, or V) doped at specific concentrations (0.1-5.0 wt%). This composite structure enhances the mechanical strength and crack resistance of silicon particles while preserving their high capacity characteristics
2Reliability
If porosity is increased to accommodate volume expansion, then crack resistance is improved, but initial efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity within the narrow range of 0.1% to 10.0% (preferably 0.5% to 5.0%). This optimized porosity level provides sufficient space for volume expansion while minimizing the loss of active material, thereby balancing crack resistance with initial efficiency
Solution Approach 2:
The patent applies local quality by creating localized pore structures within specific regions of the silicon-based active material particles. The pores are distributed throughout the particle interior, providing localized accommodation space for volume expansion without significantly reducing the overall active material content, thus maintaining initial efficiency
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 solution improves both the initial efficiency and life-span properties of lithium secondary batteries by maintaining capacity and reducing anode cracking, with optimized porosity and metal content within specific ranges.
Implementation Method 1
a plurality of silicon-based active material particles being doped with a metal element
Data Source
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AI summary
An anode active material for a secondary battery according to an embodiment includes a plurality of a silicon-based active material particle being doped with a metal element and including pores. An average of porosity values measured for each of 10 different silicon-based active material particles among the plurality of the silicon-based active material particle is in a range from 0.2% to 9.0%.