Dry Prelithiated Electrode Films for SEI Lithium Loss
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Solution Overview
Problem
Existing energy storage devices face reduced performance due to lithium consumption during the formation of the solid electrolyte interphase (SEI) layer, leading to decreased available lithium for cycling and reduced energy density.
Innovation Solution
Incorporation of a prelithiating material into the electrode film, which is mixed with conductive carbon additives and a binder to form a self-supporting, dry electrode film, allowing for prelithiation without excessive heating, thereby maintaining available lithium for cycling and increasing porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrode fabrication processes are used, then manufacturing simplicity is maintained, but lithium availability decreases due to SEI layer formation consuming lithium
Solution Approach 1:
The electrode formulation incorporates prelithiating materials (such as lithium oxide, lithium hydroxide, or lithium carbonate) mixed with the active material and binder before electrode fabrication. This preliminary incorporation of lithium sources compensates for the lithium consumed during SEI layer formation, thereby maintaining higher lithium availability for cycling without requiring complex post-fabrication treatments
Solution Approach 2:
The invention modifies the chemical composition parameters of the electrode by adding specific ratios of prelithiating materials (typically 0.1-10 wt% relative to active material) and adjusting binder content (5-20 wt%). These parameter changes enable the electrode to compensate for lithium loss while maintaining structural integrity and electrical conductivity
2Ease of manufacture
If dry electrode fabrication is used, then manufacturing cost and complexity are reduced, but achieving uniform prelithiation distribution becomes more difficult
Solution Approach 1:
The prelithiating material is segmented into fine particles (typically sub-micron to micron scale) and uniformly dispersed within the active material matrix before electrode formation. This segmentation approach ensures homogeneous lithium distribution throughout the electrode structure during dry fabrication, avoiding aggregation issues that would compromise uniformity
Solution Approach 2:
Conductive carbon additives (such as carbon black or carbon nanotubes) serve as intermediary materials that facilitate uniform distribution of prelithiating particles throughout the electrode. The carbon network acts as a dispersing matrix that prevents particle aggregation and ensures consistent lithium release during cycling
3Loss of energy
If traditional wet electrode processes are used, then electrode flexibility is improved, but solvent residues increase ESR and reduce energy density
Solution Approach 1:
The invention extracts and eliminates organic solvents (such as NMP or DMF) from the electrode fabrication process by using dry mixing and binding methods. This extraction of harmful solvents prevents ESR increase and energy density loss while maintaining electrode flexibility through alternative binding mechanisms using polymeric binders and mechanical compression
Solution Approach 2:
The wet chemical binding process is replaced with mechanical compression and fibrillization methods. The dry electrode mixture is compressed under high pressure (typically 10-100 MPa) to densify the structure and create flexible, solvent-free electrodes with low ESR and high energy density
4Stability of the object's composition
If excessive heating is applied during mixing, then material dispersion is improved, but lithium loss from prelithiating material occurs
Solution Approach 1:
The mixing process parameters are changed from high-temperature mechanical mixing to low-temperature (ambient to 100°C) high-shear mixing. This parameter change maintains lithium retention in the prelithiating material while achieving sufficient dispersion through increased shear rates and extended mixing times (typically 30-120 minutes)
Data Source
AI summary
An energy storage device can include a cathode, an anode, and a separator between the cathode and the anode. At least one of the electrodes can include an electrode film prepared by a dry process. The electrode film and/or the electrode can comprise a prelithiating material. Processes and apparatuses used for fabricating the electrode and/or electrode film are also described.