Electrochemically Reduced Graphene Electrodes Without Binder Swelling
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Solution Overview
Problem
Conventional electrodes in power storage devices face challenges in increasing charge and discharge capacity per unit weight or volume due to limitations in active material weight and binder swelling issues, leading to potential deformation and breakage when exposed to electrolytes.
Innovation Solution
The method involves electrochemically reducing graphene oxide to form graphene, using a potential range of 1.4 V to 2.6 V (preferably 1.6 V to 2.4 V vs. Li/Li+) to enhance conductivity and durability, and incorporating graphene into the active material layer to improve electrode performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrodes include conductive additives and binders to improve conductivity and structural integrity, then electrode reliability is improved, but charge and discharge capacity per unit weight or volume decreases due to increased non-active material content
Solution Approach 1:
The invention extracts and removes the binder component from the electrode structure. By forming graphene directly on the active material surface through electrochemical reduction of graphene oxide, the electrode achieves structural integrity without requiring traditional binders, thereby increasing the proportion of active material and improving charge and discharge capacity per unit weight or volume.
Solution Approach 2:
The graphene layer formed on the active material surface serves multiple functions simultaneously: it provides electrical conductivity, maintains structural integrity, and prevents active material dissolution. This multi-functional graphene layer replaces the need for separate conductive additives and binders, increasing active material content while maintaining electrode reliability.
2Strength
If conventional electrodes use binders to maintain structural integrity, then electrode strength is improved, but the electrode becomes prone to deformation and breakage when binders swell upon contact with electrolyte
Solution Approach 1:
The invention removes the binder component that causes swelling and subsequent deformation. By using graphene formed directly on the active material surface to provide structural support, the electrode eliminates the source of swelling-induced damage, thereby improving durability while maintaining strength.
Solution Approach 2:
The invention creates a composite structure where graphene is integrated with the active material surface. This composite provides both mechanical strength and resistance to electrolyte-induced degradation, as the graphene layer does not swell like traditional organic binders, thereby improving electrode durability.
3Ease of manufacture
If graphene is formed by reducing graphene oxide using conventional heat treatment methods, then graphene is produced, but conductivity is insufficient due to inadequate restoration of C(sp2)—C(sp2) double bonds
Solution Approach 1:
The invention replaces thermal energy (heat treatment) with electrochemical energy for reducing graphene oxide. By applying electrochemical reduction at controlled potentials in the range of 1.4 V to 2.6 V vs. Li/Li+, the method efficiently restores C(sp2)—C(sp2) double bonds and achieves superior conductivity compared to conventional thermal methods, while maintaining ease of manufacture within the battery system.
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
This approach results in a power storage device with higher charge and discharge capacity, reliability, and durability, as well as increased conductivity due to the higher proportion of C(sp2)—C(sp2) double bonds in the graphene formed.
Implementation Method 1
a method for forming graphene, which includes: a step of electrochemically reducing graphene oxide, thereby forming graphene
Data Source
AI summary
The formation method of graphene includes the steps of forming a layer including graphene oxide over a first conductive layer; and supplying a potential at which the reduction reaction of the graphene oxide occurs to the first conductive layer in an electrolyte where the first conductive layer as a working electrode and a second conductive layer with a as a counter electrode are immersed. A manufacturing method of a power storage device including at least a positive electrode, a negative electrode, an electrolyte, and a separator includes a step of forming graphene for an active material layer of one of or both the positive electrode and the negative electrode by the formation method.