Lithium Bromide Cell Electrolyte for Safe High-Rate Charging

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Solution Overview

Problem

Lithium-ion batteries face limitations in discharge rate, cycle life, safety due to flammability, and high cost, necessitating an improved secondary battery technology that retains their advantages while minimizing disadvantages.

Innovation Solution

A storage battery using graphite electrodes with an electrolyte of lithium bromide dissolved in lactones, forming carbon bromine and lithium carbon compounds during charging and discharge, with flexible electrode configurations and optional silicon negative electrodes, and the use of co-solvents to enhance ionic conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium-ion batteries use conventional electrolyte solutions, then ionic conductivity is achieved, but flammability and safety problems occur

Engineering Contradiction:
ImprovesafetyVSAvoidflammability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by using lithium bromide instead of conventional lithium salts, and employs cyclic carbonates (EC, PC) and chain carbonates (DMC, DEC) as solvents with specific dielectric constants and viscosity characteristics. This parameter change eliminates flammability while maintaining ionic conductivity through the unique solvation properties of carbonate esters.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The electrolyte is formulated as a composite system combining multiple carbonate esters (cyclic and chain) with lithium bromide salt. This composite approach leverages the high dielectric constant of cyclic carbonates for salt dissolution and the low viscosity of chain carbonates for ion mobility, achieving both safety and conductivity simultaneously.

Inventive Principle:
Principle #40Composite materials

2Use of energy by moving object

If lithium-ion batteries use intercalation compounds for electrodes, then energy density is improved, but discharge rate and power capability are limited

Engineering Contradiction:
Improveenergy densityVSAvoiddischarge rate
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The patent changes the electrode material parameters by using highly conductive materials such as acetylene black, graphite, and metal powders with controlled particle sizes and surface areas. The electrolyte composition is also optimized with specific carbonate ester ratios to enhance ionic conductivity, enabling faster ion transport and higher discharge rates while maintaining energy density.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If lithium-ion batteries use conventional components, then manufacturing is established, but cost remains high

Engineering Contradiction:
Improvemanufacturing processVSAvoidcost
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent employs inexpensive, readily available materials such as lithium bromide salt, common carbonate esters (EC, PC, DMC, DEC), and standard electrode materials like graphite and acetylene black. These materials can be sourced at lower costs compared to conventional lithium-ion battery components, reducing overall manufacturing cost while maintaining performance through optimized formulations.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 battery achieves improved power capability, extended cycle life, and enhanced safety by forming stable compounds during charge-discharge cycles, while reducing internal resistivity and maintaining compatibility with other components.

Implementation Method 1

The electrolyte is prepared by dissolving lithium bromide in a solvent selected from the group of lactones

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 2

During charging of the cell, bromine ions are attracted to the positive electrode forming a carbon bromine compound

Methodology Applied
Scientific EffectIon migration: Electrophoresis

Implementation Method 3

During the operation of the cell as it is repeatedly charged and discharged, lithium ions shuttle back and forth between the positive and negative electrodes

Methodology Applied
Scientific EffectIon transport: Diffusion

Data Source

PatentEP3350856B1Lithium bromide cell
Publication Date: 2019.11.20 STAUFFER JOHN E
  • EP3350856B1 patent drawingFigure 1
  • EP3350856B1 patent drawing

AI summary

A rechargeable battery is provided with a bed of particles comprising a mixture of conductive carbon granules and nonconductive granules.