Reference Electrode Preparation via Lithium Coating

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Solution Overview

Problem

Existing methods for preparing reference electrodes in lithium ion batteries face challenges such as uneven lithium coating, potential drift, and high ohmic resistance due to insufficient lithium content and poor connection between lithium and current collectors, which affect measurement durability and accuracy.

Innovation Solution

A method involving cleaning and drying a reference electrode substrate, welding it to a current collector, melting and coating it with metal lithium in an anhydrous environment, and applying a separator coating to create a stable reference electrode with controlled lithium loading, ensuring adequate lithium content and minimizing ohmic resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the size of the reference electrode is reduced to minimize lithium ion blocking, then the lithium ion circulation barrier is reduced, but the overall lithium content becomes insufficient leading to weak signals and potential drift

Engineering Contradiction:

Improvelithium ion blocking effectVSAvoidlithium content

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent employs a porous current collector substrate with controlled pore size and distribution. The porous structure allows lithium ions to circulate freely through the electrode while providing a large surface area to accommodate sufficient lithium content, thus resolving the contradiction between minimizing ion blocking and maintaining adequate lithium quantity for stable potential.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The reference electrode is constructed as a composite structure combining a porous current collector substrate with lithium-coated regions. This composite design enables the electrode to simultaneously achieve low ion transport resistance through the porous network and sufficient lithium content for stable reference potential, eliminating both the blocking effect and potential drift.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If physical crimping methods are used to connect lithium to current collector, then the connection process is simple, but the connection firmness is insufficient leading to high ohmic resistance

Engineering Contradiction:

Improveconnection process simplicityVSAvoidconnection firmness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the mechanical crimping connection method with an electrochemical deposition process. Lithium is deposited onto the current collector substrate through electrochemical reduction of lithium salts in electrolyte, creating a metallurgical bond that is far stronger and more conductive than mechanical crimping, thus eliminating high ohmic resistance while maintaining manufacturing simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent controls the electrochemical deposition parameters such as deposition potential, time, and electrolyte composition to optimize the lithium coating thickness and adhesion. By adjusting these parameters, the connection between lithium and current collector achieves both high firmness and low contact resistance, resolving the reliability issue.

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 solution provides a reference electrode with improved stability and accuracy for long-term measurements, retaining the porous structure of the substrate while ensuring sufficient lithium loading, thus enhancing the service life and measurement reliability.

Implementation Method 1

welding it to a current collector

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 2

melting and coating it with metal lithium

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

coating it with metal lithium

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 4

applying a separator coating

Methodology Applied

Scientific EffectCoating: Coatings

Data Source

PatentUS11362323B2Method for preparing reference electrode and lithium ion battery with reference electrode

Publication Date: 2022.06.14 TSINGHUA UNIVERSITY

AI summary

A method for preparing a reference electrode and a lithium ion battery with a reference electrode. In some embodiments, a method includes the following steps: welding a reference electrode substrate to a lower portion of a current collector metal sheet with a tab-film; melting metal lithium into a liquid state; immersing a lower portion of the reference electrode substrate welded with the current collector metal sheet into the liquid lithium; coating a lower portion of the tab-film with a layer of separator to obtain a reference electrode with a separator coating; inserting the reference electrode between a separator of a core of a lithium ion battery and an anode piece; and packaging in plastic the lithium ion battery implanted with the reference electrode to obtain the lithium ion battery with the reference electrode.