Graphene-Coated Bipolar Electrodes With Flame-Resistant Electrolyte
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Solution Overview
Problem
Current lithium-ion and lithium metal batteries face safety concerns due to the flammability of organic liquid electrolytes and the limitations of solid-state electrolytes, including high interfacial impedance and brittleness, which hinder the development of safe and efficient bipolar lithium batteries.
Innovation Solution
A bipolar electrode with a current collector coated in graphene or expanded graphite, featuring a quasi-solid or solid-state electrolyte composed of a nitrile and a polymer derived from a reactive additive, which includes a polymerizable liquid solvent, an initiator, and a lithium salt, preventing lithium diffusion and enhancing conductivity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If organic liquid electrolytes are used in lithium-ion and lithium metal batteries, then high lithium storage capacity and energy density are achieved, but thermal runaway and explosion safety problems occur
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to solid by using a polymer matrix (such as polyethylene oxide) that can hold lithium salts. This phase change eliminates the flammability and thermal runaway issues associated with liquid electrolytes while maintaining ionic conductivity necessary for high energy density operation.
Solution Approach 2:
The patent employs composite solid-state electrolytes combining polymer matrices with lithium salts and potentially inorganic fillers. This composite structure provides both the safety benefits of solid materials and the ionic conductivity needed for high energy density, resolving the contradiction between safety and performance.
2Object-affected harmful factors
If solid state electrolytes are used to improve safety, then fire and explosion resistance are achieved, but high interfacial impedance and brittleness reduce battery performance
Solution Approach 1:
The patent modifies the properties of solid-state electrolytes by using polymer materials that are inherently more flexible and have lower interfacial impedance compared to traditional ceramic solid electrolytes. The polymer chain structure allows for better interfacial contact and ion transport, maintaining reliability while providing safety.
Solution Approach 2:
The patent utilizes the inherent flexibility of polymer solid-state electrolytes to create thin film structures that conform well to electrode surfaces. This flexibility reduces interfacial impedance and improves contact, while the thin film structure maintains the safety benefits of solid-state operation.
3Object-affected harmful factors
If conventional ionic liquids are used as electrolyte, then non-flammability is achieved, but high viscosity and poor lithium ion transport reduce power density
Solution Approach 1:
The patent combines lithium salts with polymer matrices to create composite solid-state electrolytes. This composite structure provides the non-flammability of solid materials while the polymer chain structure facilitates lithium ion transport, achieving both safety and high power density without the viscosity problems of conventional ionic liquids.
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 provides a safe, flame-resistant electrolyte system that prevents liquid electrolyte migration, reduces interfacial impedance, and improves lithium ion conductivity, enabling the creation of high-performance bipolar lithium batteries with increased energy density and extended cycle life.
Implementation Method 1
the polymer is a polymerization or crosslinking product of a reactive additive (reactive liquid electrolyte composition), wherein the reactive additive comprises (i) a first liquid solvent that is polymerizable
Implementation Method 2
preventing lithium diffusion
Implementation Method 3
improves lithium ion conductivity
Data Source
AI summary
A bipolar electrode for a lithium battery, the bipolar electrode comprising: (a) a current collector comprising a conductive material foil having two opposing primary surfaces, wherein one or both of the primary surfaces is optionally coated with a layer of graphene or expanded graphite material; and (b) a negative electrode layer and a positive electrode layer respectively deposited on the two primary surfaces, wherein the positive electrode layer comprises a mixture of particles of a cathode active material and a quasi-solid or solid-state electrolyte and the electrolyte comprises a nitrile and a polymer, which is a polymerization or crosslinking product of a reactive additive comprising (i) a first liquid solvent that is polymerizable, (ii) an initiator or a curing agent, and (iii) a lithium salt. Also provided is a bipolar battery that comprises a plurality of bipolar electrodes connected in series.