Phosphoric Diester Salt Electrolyte for High-Temperature Na-Ion Cells

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Solution Overview

Problem

Sodium ion secondary batteries face issues with deteriorating charge-discharge characteristics and rising internal resistance at high temperatures, which affect their performance and durability.

Innovation Solution

A phosphoric acid diester salt, represented by a specific chemical formula, is used as an electrolyte or additive in a non-aqueous electrolytic solution for power storage elements, improving charge-discharge characteristics and suppressing the rise in internal resistance even after storage at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the stable film at the electrode interface remains stable during high temperature storage, then electrode protection is maintained, but the stable film may cause cracking, dissolution, or decomposition leading to deterioration of charge-discharge characteristics and increase in impedance

Engineering Contradiction:

Improvestable film stabilityVSAvoidcracking, dissolution, or decomposition of stable film

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The phosphoric acid diester salt compound acts as an intermediary substance that modifies the stable film formation process. It mediates between the electrode and the conventional electrolyte, creating a modified stable film that maintains structural integrity at high temperatures while preventing cracking, dissolution, or decomposition. The additive concentration (0.01-5% by mass) is optimized to achieve this mediating effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If conventional electrolytes are used to achieve normal temperature operation, then basic battery function is achieved, but internal resistance rises significantly after high temperature storage

Engineering Contradiction:

Improvecharge-discharge speedVSAvoidinternal resistance

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent converts the potentially harmful effect of high-temperature storage on the stable film into a beneficial outcome. By introducing the phosphoric acid diester salt additive, the stable film that would normally crack or decompose at high temperatures is transformed into a stable, low-resistance interface layer. This converts the harmful thermal degradation into a beneficial stable film formation that reduces internal resistance and improves charge-discharge characteristics after storage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 use of the phosphoric acid diester salt enhances the performance of power storage elements by maintaining charge-discharge efficiency and reducing internal resistance, even under high temperature conditions.

Implementation Method 1

it is generally interpreted that a stable film (solid electrolyte interface) is formed, which has alkali metal ion conductivity but has no electron conductivity, at an interface between the electrode active material and the electrolytic solution

Methodology Applied

Scientific EffectSolid electrolyte interface formation:

Implementation Method 2

when the alkali metal ion secondary battery is stored under high temperature environment, its stable film sometimes causes cracking, dissolution, or decomposition, thus resulting in a problem such as deterioration of charge-discharge characteristics

Methodology Applied

Scientific EffectChemical stabilization:

Data Source

PatentEP3336093B1Phosphoric acid diester salt, production method therefor, non-aqueous electrolyte for power storage element, and power storage element

Publication Date: 2023.11.01 STELLA CHEMIFA CORP

Figure 1~2

AI summary

To provide a phosphoric acid diester salt which can suppress deterioration of charge-discharge characteristics of a power storage element, and can suppress the rise in internal resistance after storage at high temperature, a production method therefor, a non-aqueous electrolytic solution for a power storage element, and a power storage element. The present invention is characterized by a phosphoric acid diester salt represented by the following chemical formula (1): wherein Mn+ represents a hydrogen ion, an alkali metal ion, an alkali earth metal ion, an aluminum ion, a transition metal ion, or an onium ion; R1 and R2 are different from each other and represent a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having at least one of a halogen atom, a heteroatom, and an unsaturated bond; and n represents a valence.