Conductive Coated Electroactive Particles for Lithium Loss Reduction
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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 electrodes.
Innovation Solution
A method for preparing an electrode material with a prelithiated electroactive material core coated with an electronically conductive layer, using solutions containing copper fluoride, titanium tetrafluoride, or other fluorides, to form a lithium fluoride and metal-based coating, which enhances stability and conductivity, reducing mechanical degradation and lithium loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-containing electroactive material is used to increase capacity, then energy density is improved, but irreversible capacity loss increases due to lithium ion loss and SEI layer formation
Solution Approach 1:
The patent applies preliminary action by pre-lithiating the silicon-containing electroactive material particles before battery assembly. This preliminary lithiation introduces excess lithium ions into the particles, which compensates for the lithium ions that will be permanently lost during subsequent cycling due to SEI layer formation and other degradation mechanisms. The pre-lithiated particles are then coated with a protective layer that preserves this excess lithium reservoir throughout battery operation.
2Ease of manufacture
If conventional electrode materials are used, then manufacturing simplicity is maintained, but mechanical degradation occurs leading to reduced cycle stability
Solution Approach 1:
The patent employs composite materials by creating a core-shell structure where silicon-containing electroactive material particles are coated with a protective shell comprising lithium fluoride and a conductive metal. This composite structure combines the high capacity benefits of silicon with the mechanical stability and conductivity advantages of the protective coating, thereby improving cycle stability while maintaining compatibility with conventional manufacturing processes.
3Reliability
If electrode material is coated to reduce degradation, then cycle stability is improved, but electronic conductivity may be reduced
Solution Approach 1:
The protective coating is composed of a composite structure with lithium fluoride providing mechanical protection and a conductive metal component (such as copper, nickel, or aluminum) providing electronic conductivity. This composite coating simultaneously addresses both the need for mechanical protection against degradation and the need for adequate electronic conductivity for power delivery.
Solution Approach 2:
The coating structure applies different properties at different locations and functions: the lithium fluoride component provides mechanical protection and chemical stability, while the conductive metal component specifically addresses electronic conductivity. This local differentiation of material properties within the coating allows simultaneous optimization of both protection and conductivity functions.
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 cycle stability, reduces capacity loss, and enhances energy density by creating a lithium reservoir and minimizing the need for conductive additives, while maintaining fast charge capabilities and extending battery life.
Implementation Method 1
The conversion reaction may be defined as y(CuF2)+LixSi→2y(LiF)+Li(x-2y)Si+yCu, where x>2y
Data Source
AI summary
The present disclosure relates to a negative electrode material and methods of preparation and use relating thereto. The electrode material comprises a plurality of electroactive material particles, where each electroactive material particle includes an electroactive material core and an electronically conductive coating. The method includes contacting an electroactive material precursor including a plurality of electroactive material particles with a solution so as to form an electronically conductive coating on each of the electroactive material particles. The solution includes a solvent and one or more of copper fluoride (CuF2), titanium tetrafluoride (TiF3 or TiF4), iron fluoride (FeF3), nickel fluoride (NiF2), manganese fluoride (MnF2, MnF3, or MnF4), and vanadium fluoride (VF3, VF4, VF5). The electronically conductive coating includes a plurality of first regions and a plurality of second regions. The plurality of first regions include lithium fluoride. The plurality of second regions include one of copper, titanium, iron, nickel, manganese, and vanadium.