Battery Electrolyte Selection for Positive-Electrode Passivation

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Solution Overview

Problem

Lithium-ion energy-storage batteries with lithium iron phosphate as the positive active material face safety issues due to increased heat generation and thermal runaway risks, especially during overcharging, which can lead to thermal runaway, fire, or explosion, exacerbated by larger cell capacities and higher energy densities.

Innovation Solution

A battery design incorporating an electrolyte selection method that includes a linear sweep voltammetry (LSV) test to determine optimal electrolyte composition, ensuring a first peak current density of 0.1 mAcm−2≤a1≤3 mAcm−2 and a first peak potential of 4.65V≤P1≤4.9V, with a film-forming additive to generate a passivation film on the positive electrode, reducing reaction heat and preventing thermal runaway.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the cell capacity and energy density are increased, then the energy storage capability is improved, but the heat generation increases and thermal runaway risk worsens

Engineering Contradiction:

Improvecell capacityVSAvoidthermal runaway risk

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an electrolyte as an intermediary substance between the positive and negative electrodes. This electrolyte contains specific additives that form protective films on the electrode surfaces, acting as a mediator that prevents direct harmful reactions while allowing ionic conduction. The electrolyte composition is carefully selected to balance ionic conductivity with thermal stability, thus enabling high capacity while mitigating thermal runaway risks.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful reaction between the electrolyte and positive electrode into a beneficial process. By controlling the first peak current density to be within 0.1-3 mAcm², the reaction generates a protective passivation film that prevents further harmful reactions. The controlled exothermic reaction at moderate current density creates a stable interface that actually protects against thermal runaway, transforming a harmful effect into a protective mechanism.

Inventive Principle:

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

2Productivity

If the first peak current density is increased to improve reaction efficiency, then the charge transfer rate is improved, but the thermal runaway risk increases

Engineering Contradiction:

Improvecharge transfer rateVSAvoidthermal runaway risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the first peak current density within the range of 0.1-3 mAcm². This parameter optimization ensures that the electrochemical reaction proceeds at an efficient rate while remaining below the threshold for thermal runaway. The current density parameter is carefully tuned to achieve the optimal balance between productivity and safety, creating a stable operating window that prevents harmful thermal effects.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the electrolyte composition is optimized to form a passivation film, then the thermal stability is improved, but the ionic conductivity may be reduced

Engineering Contradiction:

Improvethermal stabilityVSAvoidionic conductivity

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs composite materials by formulating the electrolyte as a composite system containing multiple components: lithium salts, cyclic carbonates, chain carbonates, and film-forming additives. This composite electrolyte structure allows different components to fulfill different functions - the lithium salts provide ionic conductivity, the carbonate solvents maintain fluidity, and the film-forming additives create protective passivation films. The synergistic combination of these materials achieves both thermal stability and adequate ionic conductivity.

Inventive Principle:

Principle #40Composite materials

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 method enhances battery safety by preventing thermal runaway, fire, and explosion through controlled passivation of the positive electrode, maintaining excellent cycle and overcharge performance.

Implementation Method 1

a film-forming additive to generate a passivation film on the positive electrode, reducing reaction heat and preventing thermal runaway

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

the button cell is subjected to a linear sweep voltammetry (LSV) test at a potential sweep rate of 0.1 mV/s

Methodology Applied

Scientific EffectLinear sweep voltammetry:

Data Source

PatentUS20260005309A1Battery, electrolyte selection method, and energy-storage apparatus

Publication Date: 2026.01.01 HITHIUM TECH HK LTD

AI summary

A battery, an electrolyte selection method, and an energy-storage apparatus are provided. The battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a separator, and a negative electrode which are stacked sequentially. The electrolyte at least infiltrates part of the electrode assembly, and the electrolyte contains a lithium salt. The positive electrode is obtained by disassembling the battery in a fully charged state, the positive electrode obtained and the electrolyte are assembled in a button cell, the button cell is subjected to a linear sweep voltammetry (LSV) test at a potential sweep rate of 0.1 mV/s, and a first peak current density a1 of the button cell satisfies a relationship: 0.1 mAcm−2≤a1≤3 mAcm−2.