Battery Electrolyte Passivation for Overcharge Heat Suppression
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Solution Overview
Problem
Lithium-ion energy-storage batteries face challenges with increasing heat generation and safety risks due to higher energy density and cell integration, leading to thermal runaway, fire, and explosion during overcharging.
Innovation Solution
The battery design includes an electrolyte with specific characteristics, such as a film-forming additive and a passivation film formed through polymerization and oxidation reactions, which passivate the positive electrode to prevent excessive heat generation and thermal runaway by reducing reactions between the electrolyte and transition metal oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If energy density and cell integration are increased, then productivity and energy storage capacity are improved, but heat generation increases and safety performance deteriorates
Solution Approach 1:
The patent introduces an electrolyte as an intermediary substance that forms a passivation film on the positive electrode surface. This film acts as a thermal barrier and reaction inhibitor, mediating between the high-energy electrode materials and the surrounding environment, thereby preventing thermal runaway while maintaining high energy density
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific film-forming additives and adjusting the ratio of carbonate solvents. These parameter changes enable the electrolyte to form stable passivation films at operating temperatures, effectively controlling heat generation without compromising energy storage capacity
2Reliability
If film-forming additive content is increased, then passivation film formation is improved and safety is enhanced, but cycle performance may deteriorate
Solution Approach 1:
The patent optimizes the concentration parameter of film-forming additives within a specific range (0.5-5% by mass). This parameter optimization ensures sufficient passivation film formation for safety while preventing excessive film thickness that would impede lithium ion transport and degrade cycle performance
Solution Approach 2:
The patent employs a composite electrolyte system combining multiple carbonate solvents (EC, DMF, DEC) with film-forming additives. This composite formulation creates a passivation film with balanced properties: sufficient density for safety and appropriate ion conductivity for cycle performance
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 electrolyte selection method enhances the battery's safety performance by preventing thermal runaway and explosion during overcharging, while maintaining excellent cycle and overcharge performance.
Implementation Method 1
a passivation film formed through polymerization and oxidation reactions
Implementation Method 2
a passivation film formed through polymerization and oxidation reactions
Implementation Method 3
which passivate the positive electrode to prevent excessive heat generation and thermal runaway by reducing reactions between the electrolyte and transition metal oxide
Data Source
Figure 1~2
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AI summary
A battery, an electrolyte selection method, an energy-storage apparatus, and an electricity-consumption device are provided in the disclosure. 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: 0.1mAcm-2≤a1≤3mAcm-2. The battery herein has an excellent cycle performance and an excellent overcharge performance.