Lithium Composite Negative Electrode for Room Temperature Hybrid Capacitors

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Solution Overview

Problem

Lithium-ion capacitors currently operate at around 60°C, and reducing interfacial resistance is necessary to enable operation at room temperature for practical use.

Innovation Solution

A lithium composite negative electrode comprising a laminar electrode with a lithium ion conductive solid electrolyte, an alginate gel electrolyte, and lithium-doped carbon is used, which reduces interfacial resistance, allowing the hybrid capacitor to operate at room temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a lithium composite negative electrode with polymer electrolyte and lithium ion conducting solid electrolyte is used, then high energy density and high cell voltage are achieved, but interfacial resistance increases significantly at room temperature

Engineering Contradiction:

Improveenergy densityVSAvoidinterfacial resistance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An alginate gel electrolyte layer is introduced as an intermediary between the lithium ion conducting solid electrolyte and the lithium-doped carbon. This gel electrolyte acts as a mediator that reduces interfacial resistance at room temperature while maintaining the high energy density and voltage characteristics of the original lithium composite electrode structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite electrolyte system combining alginate gel electrolyte with lithium ion conducting solid electrolyte. This composite material approach allows the system to benefit from both the high ion conductivity of the solid electrolyte and the low interfacial resistance of the gel electrolyte at room temperature.

Inventive Principle:

Principle #40Composite materials

2Temperature

If lithium-doped carbon is used as the active material layer, then room temperature operation is enabled, but the manufacturing process becomes more complex

Engineering Contradiction:

Improveoperating temperatureVSAvoidmanufacturing process complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

Lithium doping of the carbon material is performed as a preliminary action during the electrode manufacturing process. By incorporating lithium into the carbon structure beforehand, the electrode is pre-prepared for room temperature operation, eliminating the need for separate lithium doping steps and simplifying the overall manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If hybrid capacitor operates at room temperature, then practical usage is enabled, but interfacial resistance must be reduced

Engineering Contradiction:

Improveoperating temperature rangeVSAvoidinterfacial resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The alginate gel electrolyte serves as an intermediary layer that enables room temperature operation by reducing interfacial resistance between the solid electrolyte and carbon active material. This mediator allows the hybrid capacitor to adapt to room temperature conditions while maintaining reliable electrical performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution enables a hybrid capacitor to operate safely and durably at room temperature with high energy density and high cell voltage, while also simplifying the manufacturing process by eliminating the need for separate lithium-doped material incorporation.

Implementation Method 1

a lithium ion conductive solid electrolyte, an alginate gel electrolyte, and a lithium-doped carbon

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

an alginate gel electrolyte which reduces interfacial resistance in the electrode

Methodology Applied

Scientific EffectGel electrolyte conduction: Conduction (electrical)

Implementation Method 3

performing galvanostatic or potentiostatic electrolysis, and doping lithium into the carbon material not doped with lithium

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Data Source

PatentEP3428941B1Lithium composite negative electrode and hybrid capacitor, and manufacturing methods thereof

Publication Date: 2021.09.22 SHINSHU UNIVERSITY

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AI summary

Provided is a lithium composite negative electrode which allows a hybrid capacitor to operate at room temperature by reducing interfacial resistance in the electrode, a hybrid capacitor comprising the composite negative electrode, and manufacturing methods thereof. The above-described problem is solved by a lithium composite negative electrode (12), which is a laminar electrode comprising a lithium ion conductive solid electrolyte (23), an alginate gel electrolyte (22), and lithium-doped carbon (21). Further, a hybrid capacitor (1) comprises at least a positive electrode (11) comprising one or both of a carbon material and a metal oxide, the lithium composite negative electrode (12), and a neutral aqueous electrolyte (13) filled between the positive electrode (11) and the lithium composite negative electrode (12). The lithium composite negative electrode (12) is configured as a laminar electrode comprising the lithium ion conductive solid electrolyte (23), the alginate gel electrolyte (22), and the lithium-doped carbon (21).