SEI Preformed Graphite for Lithium Loss Compensation
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Solution Overview
Problem
Conventional lithium-ion batteries suffer from irreversible lithium loss due to the formation of a solid electrolyte interphase (SEI) on the graphite anode, which reduces energy density and requires cumbersome prelithiation techniques that compromise cathode active material loading and safety.
Innovation Solution
A method to preform an SEI layer directly on graphite particles using a flow cell apparatus, where graphite particles are suspended in an electrolyte and subjected to a voltage between a cathode and an anode, forming a stable SEI coating that mitigates initial lithium loss without inactive residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional graphite anode is used in lithium-ion batteries, then the battery structure is simple and easy to manufacture, but irreversible lithium loss occurs due to SEI formation which reduces energy density
Solution Approach 1:
The patent applies preliminary action by pre-forming the SEI layer on graphite particles before assembling the battery. The graphite particles are suspended in electrolyte and subjected to controlled voltage to form a stable SEI coating in advance, so that when the battery operates, no additional lithium is consumed for SEI formation, thus eliminating initial lithium loss and improving energy density while maintaining simple battery structure
2Loss of energy
If cathode prelithiation with high Li content sacrificial reagents is used to compensate lithium loss, then the lithium loss is compensated and energy density increases, but the active cathode material loading is reduced and inactive residues are generated
Solution Approach 1:
The patent extracts the SEI formation process from the battery assembly process. Instead of adding sacrificial reagents to the cathode, the method separately pre-treats graphite particles by suspending them in electrolyte and applying voltage to form SEI layers before electrode assembly. This eliminates the need for additional lithium compensation materials and maintains full cathode active material loading
3Reliability
If artificial SEI coating is applied to protect anode material from side reactions, then initial Coulombic efficiency is elevated, but it is difficult to control the loading to a precise level
Solution Approach 1:
The patent employs feedback control through electrochemical monitoring during SEI formation. The process uses controlled voltage application and monitors current decay to determine when SEI formation is complete, providing precise control over SEI coating loading on graphite particles without requiring complex additional measurement systems
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 increases the initial Coulombic efficiency by 10% and compensates approximately 25 mAh g−1 of initial lithium loss, enhancing energy density and safety by eliminating the need for additional lithium compensation methods.
Implementation Method 1
forming an SEI coating on the individual graphite particles in the suspension by generating a voltage between the cathode and the anode and across the suspension
Data Source
AI summary
Solid electrolyte interphase (SEI) preformed graphite, methods of forming SEI preformed graphite, apparatus for forming SEI preformed graphite, and electrochemical battery cells including an SEI preformed graphite electrode. A method of making SEI preformed graphite includes forming an SEI coating on individual graphite particles in a suspension of graphite particles in an electrolyte by generating a voltage between a cathode and an anode having a lithium source across the suspension. An SEI preformed graphite includes a graphite powder having a preformed SEI layer on each of a plurality of graphite particles in powder form. The SEI layer covers the exterior surface of each of the graphite particle in the graphite powder. An electrochemical battery cell may be formed using the SEI preformed graphite. A flow cell apparatus is provided for forming the SEI preformed graphite.