Lithium Battery Electrolyte Additive and Electrode Layout for Low Swelling
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Solution Overview
Problem
Conventional lithium batteries suffer from poor long-term stable working performance due to electrolyte solution decomposition, side reactions with positive electrode active material, lithium plating, and battery expansion, leading to capacity decay, safety issues, and potential explosion.
Innovation Solution
A battery design incorporating a first additive in the electrolyte solution, a specific proportion of positive electrode active material layer on the current collector, and a termination tape with controlled thickness to form a protective barrier, reducing side reactions and expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrolyte solution is used in conventional lithium batteries, then ionic conductivity and electrochemical performance are achieved, but side reactions with positive electrode active material occur under long-term use or specific conditions, leading to decomposition and deterioration of the electrolyte solution
Solution Approach 1:
The patent introduces a protective film formed by a specific additive (lithium difluorophosphate) as an intermediary layer between the electrolyte solution and the positive electrode active material. This protective film acts as a mediator that prevents direct contact and side reactions between the electrolyte and electrode materials, thereby eliminating the harmful decomposition reactions while maintaining ionic conductivity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte solution by adding lithium difluorophosphate at a specific concentration range (0.1-5 wt%). This parameter change transforms the electrolyte's properties, enabling it to form a stable protective film on the electrode surface that prevents decomposition while maintaining electrochemical performance.
2Reliability
If side reactions between electrolyte solution and positive electrode active material occur, then battery capacity decay and energy density reduction happen, but lithium plating on negative electrode surface increases, causing safety issues
Solution Approach 1:
The protective film formed by the additive serves as an intermediary barrier that prevents lithium ions from directly plating on the negative electrode surface. By mediating the lithium ion transport and distribution, the protective film eliminates the harmful lithium plating effect while maintaining battery capacity and cycle life.
3Reliability
If electrolyte solution decomposes to produce gas and positive/negative electrode active materials undergo volumetric expansion during charge/discharge cycling, then internal pressure increases and structural damage occurs, but battery expansion and potential explosion are caused
Solution Approach 1:
The patent applies preliminary anti-action by introducing the lithium difluorophosphate additive that proactively forms a protective film on the electrode surfaces before gas-producing decomposition reactions can occur. This preliminary protective action prevents the subsequent harmful effects of gas production and battery expansion, maintaining structural integrity throughout cycling.
Solution Approach 2:
The protective film acts as an intermediary barrier that prevents direct decomposition reactions between the electrolyte and electrode materials, thereby eliminating gas production. This intermediary layer maintains pressure equilibrium and prevents the chain reaction leading to battery expansion and potential explosion.
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 exhibits reduced gas production, lithium plating, and expansion, resulting in improved cycle life and cycling stability.
Implementation Method 1
the first additive not only has high stability but also efficiently complexes with metal ions on the surface of the positive electrode plate, forming a barrier between the positive electrode plate and the electrolyte solution
Implementation Method 2
the positive electrode active material and the negative electrode active material in the battery produce volumetric expansion during the charge/discharge cycling process, causing the battery to produce gas and expand
Data Source
AI summary
A battery includes an electrolyte solution and a positive electrode plate. The electrolyte solution includes a first additive, and a weight content of the first additive in the electrolyte solution is A; the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, and a proportion of an orthographic projection of the positive electrode active material layer on the positive electrode current collector is B; the battery further includes a termination tape, and a thickness of the termination tape is C, in μm; A, B, and C satisfy: 18≤19×B+0.38×C−100×A≤38. The battery of the present disclosure has less gas generation and expansion during the cycling process, and exhibits excellent cycle life and cycling stability.