Battery Electrolyte Composition for SEI Stability and Fast Cycling

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Solution Overview

Problem

Secondary batteries face challenges in achieving both good dynamic performance and high-temperature cycling performance, with inadequate protection of the negative electrode, leading to poor performance under varying conditions.

Innovation Solution

An electrolyte solution comprising a cyclic ester solvent, a linear carboxylic ester solvent, a film-forming additive, and a lithium salt, with specific mass fractions that form a stable SEI film on the negative electrode, enhancing electrical conductivity and reducing viscosity, while a secondary battery design with a lithium-containing phosphate olivine structure positive electrode active material improves energy density and dynamic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolyte formulations are used, then basic battery operation is maintained, but dynamic performance and high-temperature cycling performance are insufficient

Engineering Contradiction:

Improvehigh-temperature cycling performanceVSAvoiddynamic performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the mass fractions of lithium salt (W1), film forming additive (W2), and linear carboxylic ester solvent (W3) to satisfy the relationship 0.2≤(W1+W2)/W3≤0.4. This quantitative parameter optimization resolves the contradiction by achieving both improved reliability through stable SEI film formation and maintained productivity through appropriate electrolyte composition for dynamic performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining cyclic ester solvent, linear carboxylic ester solvent, film forming additive, and lithium salt in specific proportions. This composite electrolyte system resolves the technical contradiction by synergistically achieving both high-temperature cycling stability and dynamic performance that cannot be obtained with single-component electrolytes.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the negative electrode is not fully protected, then battery capacity may be higher, but performance under varying conditions deteriorates

Engineering Contradiction:

Improveperformance under varying conditionsVSAvoidbattery capacity

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by using the film forming additive to form a stable SEI film on the negative electrode before the battery enters service. This preliminary protective action resolves the contradiction by ensuring the negative electrode is fully protected from the start, enabling the battery to maintain good performance under varying conditions including high-temperature cycling.

Inventive Principle:

Principle #10Preliminary action

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 achieves both good dynamic performance and high-temperature cycling performance, ensuring full protection of the negative electrode and enhancing the overall battery performance, including energy density and capacity retention.

Implementation Method 1

the film forming additive has a mass fraction of W2... Through the selection of the film forming additive, the present application can form a solid electrolyte interphase (SEI) film well on a negative electrode

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) film formation: Deposition (physical)

Implementation Method 2

By using the cyclic ester solvent, the present application can improve the electrical conductivity of the battery

Methodology Applied

Scientific EffectElectrical conductivity enhancement: Conduction (electrical)

Implementation Method 3

Through the selection of the linear carboxylic ester solvent, the present application can reduce the viscosity of the electrolyte solution

Methodology Applied

Scientific EffectViscosity reduction:

Data Source

PatentUS20230335807A1Electrolyte solution, secondary battery and power consuming device

Publication Date: 2023.10.19 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

The present application provides an electrolyte solution, a secondary battery and a power consuming device. The electrolyte solution may contain a solvent, an additive and a lithium salt. The solvent may include a first solvent and a second solvent, the first solvent being a cyclic ester solvent, and the second solvent being a linear carboxylic ester solvent. The additive may include a film forming additive. Based on the total mass of the electrolyte solution, the lithium salt may have a mass fraction of W1, the film forming additive may have a mass fraction of W2, and the second solvent may have a mass fraction of W3, which may satisfy the following relationship: 0.2≤(W1+W2)/W3≤0.4.