Power Storage Device Electrolyte Solvent Sequencing for Stable Coating

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Solution Overview

Problem

Lithium-ion secondary batteries face degradation due to repeated charge and discharge cycles, leading to capacity loss and operational issues, particularly due to chemical reactions between materials in the electrolytic solution, making it difficult to determine the cause of deterioration and design optimal battery structures.

Innovation Solution

A method for manufacturing power storage devices involves initially contacting a solvent for the electrolytic solution with the positive and negative electrodes, followed by adding a different solvent to adjust the solution, using high dielectric constant solvents like ethylene carbonate, and performing charge and discharge cycles under controlled conditions to form stable coating films, thereby inhibiting deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If three or more kinds of materials for an electrolytic solution are mixed to widen the operation temperature range, then the temperature adaptability is improved, but the number of chemical reactions increases and the internal state becomes more complex

Engineering Contradiction:

Improveoperation temperature rangeVSAvoidinternal state complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-forming stable coating films on the electrodes using high dielectric constant solvents like ethylene carbonate before introducing other electrolytic solution materials. This preliminary coating formation prevents unwanted chemical reactions between different electrolytic solution materials, thereby simplifying the internal state while maintaining wide temperature adaptability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses high dielectric constant solvents as intermediary substances that form protective coating films on the electrodes. These coating films act as intermediaries between different electrolytic solution materials, preventing direct harmful chemical reactions while allowing the system to benefit from multiple materials' temperature adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If various materials are used in the electrolytic solution to improve performance, then the energy density and cycle performance are improved, but side reactions occur and battery deterioration accelerates

Engineering Contradiction:

Improvecycle performanceVSAvoidside reactions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by using high dielectric constant solvents to form stable coating films on the electrodes before other electrolytic solution materials can cause harmful side reactions. This preliminary protective action prevents decomposition and other unwanted chemical reactions, thereby improving cycle performance while minimizing harmful effects.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If trial and error methods are used to determine optimal material combinations, then the battery performance can be optimized, but enormous time is expended for analysis and material selection

Engineering Contradiction:

Improvebattery performanceVSAvoidtime for material analysis

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies parameter changes by focusing on the dielectric constant parameter of electrolytic solution solvents. By identifying high dielectric constant solvents (≥20) like ethylene carbonate as effective for forming stable coating films, the patent provides a clear selection criterion that eliminates the need for extensive trial and error, significantly reducing material analysis time while optimizing battery 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

This approach improves the cycle performance and temperature range of power storage devices, allowing them to function effectively from -40°C to 80°C by forming stable coating films that reduce side reactions and extend battery life.

Implementation Method 1

In initial charge and discharge of a battery, the chemical reaction between materials might be accelerated or another chemical reaction (including electrolysis) might occur to generate decomposition products or a gas

Methodology Applied

Scientific EffectElectrochemical reaction:

Implementation Method 2

using high dielectric constant solvents like ethylene carbonate

Methodology Applied

Scientific EffectDielectric constant effect: Dielectric Permittivity

Data Source

PatentUS11355784B2Power storage device and manufacturing method thereof

Publication Date: 2022.06.07 SEMICON ENERGY LAB CO LTD

AI summary

In initial charge and discharge, decomposition products or a gas is generated, degrading a battery. At least one of solvents (e.g., ethylene carbonate) used for an electrolytic solution is brought into contact with a positive electrode and a negative electrode and then charge is performed to some degree, and after that, a different solvent or electrolytic solution (e.g., ethyl methyl carbonate or vinylene carbonate) was added to adjust the electrolytic solution and then charge is performed. Through this process, stable coating films are formed in initial charge and discharge, which stably inhibits a side reaction between the electrolytic solution and an active material.