Fluorinated Copolymer-Coated Li-Ion Anode for Dendrite Suppression

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Solution Overview

Problem

Lithium-ion batteries face challenges with the formation of lithium dendrites during charging, leading to low coulombic efficiency, increased cell volume, electrolyte decomposition, and potential short circuits, which are difficult to stabilize using existing methods like microspheres or protective layers that are sensitive to moisture and oxygen.

Innovation Solution

A fluorinated copolymer or terpolymer film is deposited on the anode surface to inhibit lithium dendrite formation, utilizing copolymers like P(VDF-TrFE) or P(VDF-TFE) and terpolymers such as P(VDF-TrFE-CTFE), which are ferroelectric or relaxor ferroelectric, to orient lithium cations parallel to the collector, reducing dendrite growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a Li metal anode is used to increase energy density, then the energy density increases significantly, but lithium dendrites form during charging which causes low coulombic efficiency, increased cell volume, electrolyte decomposition, and potential short circuits

Engineering Contradiction:
Improveenergy densityVSAvoiddendrite formation
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-forming a protective SEI layer on the Li metal anode surface before actual battery operation. This is achieved by initial charging cycles that reduce electrolyte components (VC, FEC, LiPF6) to form a stable protective interface layer, preventing dendrite formation during subsequent charging cycles

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses electrolyte additives (VC, FEC, LiPF6) as intermediaries that mediate between the Li metal anode and the bulk electrolyte. These additives preferentially decompose to form a stable SEI layer that acts as a protective intermediary, preventing direct contact between Li metal and the bulk electrolyte, thus suppressing dendrite growth and electrolyte decomposition

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If protective layers or additives are used to stabilize the Li anode interface, then dendrite formation is reduced, but the handling becomes tricky due to sensitivity to moisture and oxygen

Engineering Contradiction:
Improveinterface stabilizationVSAvoidhandling difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies self-service by enabling the Li metal anode to self-form its own protective SEI layer through controlled initial charging cycles. The electrolyte additives (VC, FEC, LiPF6) automatically reduce on the Li surface to form the protective interface, eliminating the need for external protective coatings that require complex handling and assembly in inert atmospheres

Inventive Principle:
Principle #25Self-service

3Reliability

If graphite anodes are used instead of Li metal, then dendrite formation is avoided, but the energy density increases are limited

Engineering Contradiction:
Improvedendrite-free operationVSAvoidenergy density
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the parameters of the Li metal anode system by controlling the composition and thickness of the SEI layer through electrolyte additive selection. By adjusting the ratios of VC, FEC, and LiPF6, and controlling initial charging conditions, the SEI layer properties are optimized to enable Li metal operation with high energy density while maintaining dendrite-free performance

Inventive Principle:
Principle #35Parameter changes

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 fluorinated film effectively prevents or reduces lithium dendrite formation, enhancing the stability and performance of lithium-ion batteries, particularly at high charge/discharge rates, and improving the service life of the batteries.

Implementation Method 1

utilizing copolymers like P(VDF-TrFE) or P(VDF-TFE) and terpolymers such as P(VDF-TrFE-CTFE), which are ferroelectric or relaxor ferroelectric, to orient lithium cations parallel to the collector

Methodology Applied
Scientific EffectFerroelectric effect:

Implementation Method 2

A fluorinated copolymer or terpolymer film is deposited on the anode surface to inhibit lithium dendrite formation

Methodology Applied
Scientific EffectSolid electrolyte interface formation:

Data Source

PatentUS12199287B2Anode for Li-ion battery
Publication Date: 2025.01.14 ARKEMA FRANCE SA

AI summary

The invention relates to an anode for a Li-ion rechargeable battery, said anode being covered with a protective film based on fluorinated copolymer(s). The invention also relates to the processes for preparing this anode. The invention also relates to a Li-ion rechargeable battery comprising an anode according to the invention. The invention lastly relates to the use of fluorinated copolymer(s) as film for covering an anode for a lithium-ion battery comprising a negative electrode active material.