TTSP Electrolyte Additive for LVPF Cathode Capacity Retention

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Solution Overview

Problem

Lithium vanadium fluorophosphate (LVPF) cathode active materials in lithium-ion batteries suffer from initial capacity loss due to vanadium dissolution into the electrolyte, which affects cycling stability.

Innovation Solution

Incorporating tris(trimethylsilyl) phosphate (TTSP) as an electrolyte additive in lithium-ion secondary batteries with LVPF as the cathode active material to suppress initial capacity loss and improve cycling stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If LVPF is used as a cathode active material to achieve high energy density, then energy density is improved, but initial capacity loss occurs due to vanadium dissolution

Engineering Contradiction:

Improveenergy densityVSAvoidcycling stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

TTSP acts as an intermediary substance in the electrolyte that mediates between the LVPF cathode and the electrolyte environment. It forms a protective interface layer that prevents direct harmful interaction between vanadium and the electrolyte, thereby suppressing vanadium dissolution while maintaining the high energy density benefits of LVPF

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameter of the electrolyte by adding TTSP at concentrations of 0.1-10 wt%. This parameter change modifies the electrolyte's interaction with the cathode material, reducing vanadium dissolution and improving cycling stability without sacrificing the high energy density characteristics of LVPF

Inventive Principle:

Principle #35Parameter changes

2Productivity

If vanadium dissolves into the electrolyte to enable charge transfer, then electrochemical activity is achieved, but capacity loss and SEI formation occur

Engineering Contradiction:

Improveelectrochemical activityVSAvoidcapacity loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The invention converts the potentially harmful effect of vanadium dissolution into a beneficial outcome. TTSP controls the dissolution process to form a stable vanadium-containing surface layer on the cathode that actually protects against further dissolution and improves structural stability, thereby converting capacity loss into a protective mechanism

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 TTSP significantly reduces initial capacity loss and enhances cycling stability in lithium-ion batteries by preventing vanadium dissolution and solid electrolyte interphase (SEI) issues.

Implementation Method 1

tris(trimethylsilyl) phosphate (TTSP) can be used as an electrolyte additive to significantly suppress initial capacity loss when using LVPF as a cathode active material

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

vanadium (V) dissolves or otherwise dissociates into the electrolyte, is reduced at the anode, and forms a film/metal on the anode

Methodology Applied

Scientific EffectDissolution prevention: Physical Containment

Implementation Method 3

which may cause problems with the solid electrolyte interphase (SEI)

Methodology Applied

Scientific EffectSEI stabilization:

Data Source

PatentEP4421918A1Lithium-ion secondary battery with electrolyte additive

Publication Date: 2024.08.28 SAFT AMERICA INC

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AI summary

Provided is a lithium-ion secondary batteries including lithium vanadium fluorophosphate (e.g., LiVPO4F and its derivatives) and/or a mix containing LVPF as a positive electrode active material and an electrolytic solution including tris(trimethylsilyl) phosphate (TTSP) to reduce cycle capacity loss.