Lithium Secondary Battery Protection Layer for Dendrite Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face degradation and cell short circuits due to the growth of lithium dendrites, which are exacerbated by side reactions involving the electrolyte, leading to reduced battery life and safety concerns.
Innovation Solution
A lithium secondary battery design incorporating a hydrophilically surface-modified porous polyolefin film protection layer on the anode, with a specific contact angle and pore structure, combined with a high concentration electrolyte, to inhibit non-uniform lithium dendrite growth and minimize side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as anode material to achieve high energy density, then battery capacity is improved, but lithium dendrite growth occurs leading to short circuits and reduced reliability
Solution Approach 1:
A protection layer comprising a porous polymer coating layer and a hydrophilic surface modified porous polyolefin film is introduced as an intermediary between the lithium metal anode and the electrolyte. This protection layer prevents direct contact between the electrolyte and lithium metal, thereby inhibiting lithium dendrite growth while maintaining high battery capacity. The porous structure allows lithium ion transport while the hydrophilic surface modification reduces electrolyte side reactions.
2Ease of manufacture
If conventional polyolefin protection layer is used, then manufacturing is simple, but contact angle with electrolyte is high causing poor wettability and increased side reactions
Solution Approach 1:
The surface properties of the polyolefin protection layer are modified by hydrophilic treatment, which changes the contact angle parameter from high (poor wettability) to low (good wettability). This surface modification increases hydrophilicity, reducing electrolyte side reactions while maintaining the simplicity of the base polyolefin structure. The contact angle is specifically controlled to be 40° or less.
3Speed
If protection layer porosity is increased to allow lithium ion transport, then ion conductivity is improved, but mechanical strength decreases allowing dendrite penetration
Solution Approach 1:
The protection layer is designed as a composite structure combining a porous polymer coating layer with a hydrophilic surface modified porous polyolefin film. The porous polymer coating layer provides mechanical strength and dendrite resistance, while the porous polyolefin film provides ion transport pathways. This composite structure achieves both high lithium ion conductivity and sufficient mechanical strength to prevent dendrite penetration.
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 solution effectively enhances the battery's life characteristic and stability by promoting uniform lithium dendrite growth and reducing electrolyte side reactions, thereby preventing short circuits and improving overall performance.
Implementation Method 1
the protection layer comprises a hydrophilically surface modified porous polyolefin film
Implementation Method 2
the protection layer has a contact angle to an electrolyte prepared by dissolving LiFSI in a solvent mixture of polycarbonate and dimethylcarbonate in a volume ratio of 3:7 at the concentration of 3.5 M, of 40° or less
Implementation Method 3
the pore size of the protection layer may be 10 nm to 1000 nm, and the porosity may be 20% to 80%
Implementation Method 4
The protection layer may be hydrophilically surface modified by plasma treatment
Implementation Method 5
the electrolyte comprises an organic solvent and lithium salts, and wherein the lithium salt are present at a concentration range of 2 M to 7 M
Data Source
AI summary
A lithium secondary battery exhibiting excellent life characteristic and stability is discussed, in which side reactions of an electrolyte are minimized, and non-uniform growth of lithium dendrite is effectively inhibited.