LiFSI-LiPF6 Electrolyte Composition for High-Density Battery Kinetics

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Solution Overview

Problem

Existing electrochemical apparatuses face challenges in achieving high energy density while maintaining kinetic/rate performance, especially at low temperatures, due to issues such as increased viscosity from high lithium salt concentrations, corrosion of aluminum foils, and reduced liquid retention leading to poor kinetic performance.

Innovation Solution

An electrolyte formulation comprising lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6) with specific weight percentages, along with other additives like ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC), is used to optimize the electrolyte composition, ensuring sufficient lithium ions, low viscosity, and improved thermal stability, thereby enhancing the electrochemical apparatus's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the percentage of Ni in lithium transition metal oxide positive electrode material is increased to form high-nickel material, then the gram capacity of the positive electrode material is improved, but the kinetic performance of the material decreases and residual alkali on the surface increases leading to gas production

Engineering Contradiction:

Improvegram capacity of positive electrode materialVSAvoidkinetic performance and gas production

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces an intermediary substance (coating layer or surface modification agent) between the high-nickel positive electrode material and the electrolyte to prevent harmful interactions. This coating reduces residual alkali exposure to the electrolyte, preventing gas production while maintaining the high capacity benefits of nickel-rich materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies surface parameters of the positive electrode material through chemical or physical treatment, changing the surface composition or structure to reduce alkalinity without altering the bulk nickel content. This allows maintaining high gram capacity while improving kinetic performance and reducing gas evolution.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the compacted density of active material layers in positive and negative electrode plates is increased, then the volumetric energy density of the electrochemical apparatus is improved, but the porosity of the electrode plates decreases and liquid retention of the electrolyte is reduced leading to poor kinetic performance

Engineering Contradiction:

Improvevolumetric energy densityVSAvoidkinetic performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies different density characteristics to different regions of the electrode structure. The active material layers are packed densely for high energy density, while the electrolyte retention layers or porous structures are maintained with higher porosity to ensure adequate liquid retention and kinetic performance. This local differentiation resolves the contradiction between volumetric energy density and kinetic performance.

Inventive Principle:

Principle #3Local quality

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 optimized electrolyte formulation achieves excellent rate, low-temperature, and high-temperature performance, as well as cycling stability, by balancing the concentrations of various components to prevent corrosion and maintain effective kinetic performance.

Implementation Method 1

The electrolyte includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6)

Methodology Applied

Scientific EffectElectrolyte dissociation: Electrolysis

Implementation Method 2

ensuring sufficient lithium ions, low viscosity, and improved thermal stability

Methodology Applied

Scientific EffectViscosity reduction through electrolyte composition:

Implementation Method 3

balancing the concentrations of various components to prevent corrosion

Methodology Applied

Scientific EffectCorrosion prevention:

Implementation Method 4

improved thermal stability, thereby enhancing the electrochemical apparatus's performance

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentUS20260074291A1Electrolyte and electrochemical apparatus including such electrolyte

Publication Date: 2026.03.12 NINGDE AMPEREX TECHNOLOGY LTD

AI summary

An electrolyte including lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, where based on a total weight of the electrolyte, a weight percentage of lithium bis(fluorosulfonyl)imide is a %, and a weight percentage of lithium hexafluorophosphate is b %, where 12<a+b<20 and 0.2<a/b<1.5. An electrochemical apparatus using the electrolyte described in this application can achieve high energy density while also ensuring rate performance at room temperature and high temperature and cycling stability at room temperature and high temperature.