Prelithiated Silicon Alloy Particles for Low-Loss Li-Ion Anodes
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Solution Overview
Problem
Conventional lithium-ion batteries experience irreversible capacity loss due to lithium ion loss and solid electrolyte interphase formation, leading to decreased specific energy and power, particularly in silicon-containing negative electrodes.
Innovation Solution
A method of forming a lithiated silicon-based precursor material through a centrifugal atomization process, where lithium and silicon are mixed at controlled temperatures and pressures to create a prelithiated alloy with specific particle sizes and compositions, such as Li4.4xSi, to minimize lithium evaporation and improve alloy homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-containing negative electrodes are used to increase capacity, then energy density is improved, but irreversible capacity loss increases due to lithium ion loss and solid electrolyte interphase formation
Solution Approach 1:
The patent applies preliminary action by pre-lithiating the silicon-based negative electrode material before battery assembly. The negative electrode is prepared with an excess of lithium ions incorporated into the silicon structure in advance, which compensates for the lithium ions that will be lost during initial charging cycles due to SEI formation. This preliminary lithium incorporation ensures that the electrode maintains sufficient lithium content for reversible cycling after formation.
2Ease of manufacture
If conventional mixing methods are used to combine lithium and silicon, then manufacturing simplicity is maintained, but alloy homogeneity deteriorates and lithium evaporation increases
Solution Approach 1:
The patent utilizes phase transitions by melting both lithium and silicon to form a liquid alloy mixture, then rapidly cooling it to solidify into a homogeneous precursor. This controlled phase transition from solid to liquid and back to solid ensures uniform distribution of lithium and silicon at the atomic level, creating a homogeneous alloy that prevents lithium evaporation and improves electrochemical performance.
3Speed
If particle size is reduced to improve electrochemical performance, then reaction kinetics are enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate and solidification conditions during the alloy formation process to produce particles with optimized size distribution. By adjusting parameters such as cooling rate, mold temperature, and alloy composition, the process generates particles in the optimal size range that enhances reaction kinetics while maintaining manufacturability and consistent quality.
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 process results in improved cycle stability and reduced lithium consumption, maintaining charge capacity for extended periods with minimal capacity fade, enhancing the mechanical properties and longevity of lithium-ion batteries.
Implementation Method 1
centrifugally distributing the precursor by contacting the precursor with a rotating surface in a centrifugal atomizing reactor
Implementation Method 2
solidifying the precursor to form a plurality of substantially round solid electroactive particles
Data Source
AI summary
Methods for forming prelithiated electroactive materials are provided. Methods include preparing a precursor that includes lithium and silicon and centrifugally distributing the precursor using a centrifugal atomizing reactor. Methods for preparing the precursor include contacting a first mixture including lithium and having a first temperature and a second mixture including silicon and having a second temperature in a mixing chamber to form a precursor. The first mixture and the second mixture each enters the mixing chamber at a pressure greater than or equal to about 10 PSI. The second temperature is greater than the first temperature. Centrifugally distributing the precursor includes contacting the precursor with a rotating surface in a centrifugal atomizing reactor and solidifying the precursor to form a plurality of substantially round solid electroactive particles including lithium and silicon and having D50 diameters of less than or equal to about 30 micrometers.