Multilayer Graphene Positive Electrode for Lithium-Ion Batteries
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Solution Overview
Problem
Lithium-ion secondary batteries face reduced discharge capacity and structural deformation due to the inclusion of conductive additives and binders in the positive electrode active material layer, which swell when exposed to electrolyte solutions.
Innovation Solution
The use of multilayer graphene to connect and hold particles of the positive electrode active material, reducing the need for conductive additives and binders, thereby maintaining the electrode structure and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive additive and binder are included in the positive electrode active material layer, then the conductivity and structural integrity are improved, but the discharge capacity per unit weight decreases
Solution Approach 1:
The patent removes the binder component from the electrode structure entirely, relying on the mechanical interlocking and conductive network formed by the conductive additive particles to maintain structural integrity. This extraction of the binder eliminates its harmful swelling effect while preserving necessary electrode coherence through alternative mechanisms.
Solution Approach 2:
The conductive additive serves multiple functions simultaneously: it provides electrical conductivity, maintains structural integrity through particle interlocking, and prevents electrode deformation. This multi-functionality eliminates the need for separate binder components, thereby increasing the proportion of active material and improving discharge capacity per unit weight.
2Strength
If a binder is included in the positive electrode active material layer, then the binding of particles and current collector is improved, but the electrode is likely to be deformed and broken due to swelling
Solution Approach 1:
The patent extracts the binder component from the electrode formulation, eliminating the source of swelling-induced deformation and breakage. Structural integrity is maintained through alternative mechanisms involving conductive additive networks and particle interlocking, which do not exhibit the harmful swelling behavior of polymeric binders.
Solution Approach 2:
The patent employs inorganic conductive additive particles that provide structural support without the long-term degradation issues of organic binders. These particles maintain their structural properties throughout the battery's operational life, providing durable binding functionality without swelling or decomposition.
3Quantity of substance
If the percentage of active material is increased, then the capacity of the battery is increased, but the amounts of conductive additive and binder needed are reduced, affecting conductivity and structure
Solution Approach 1:
The conductive additive is designed to perform multiple functions: providing electrical conductivity pathways, maintaining structural integrity, and preventing particle aggregation. This multi-functionality allows for higher active material content while preserving necessary electrode properties, as the conductive additive replaces both the conductivity and structural roles of traditional binder-conductive additive combinations.
Solution Approach 2:
The patent optimizes the particle size, shape, and distribution parameters of the conductive additive to maximize its efficiency in providing both conductivity and structural support. By adjusting these parameters, the conductive additive can effectively maintain electrode structure with minimal quantity, enabling higher active material loading.
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 increases the discharge capacity and durability of the power storage device by maintaining the bond between particles and preventing structural collapse during charging and discharging, while also reducing the amount of binder and conductive additive required.
Implementation Method 1
multilayer graphene with which a plurality of particles of the positive electrode active material are at least partly connected to each other
Implementation Method 2
lithium in a positive electrode material is ionized into a lithium ion and the lithium ion is moved into a carbon material of a negative electrode material through an electrolyte solution
Implementation Method 3
the binder included in the positive electrode active material layer swells as it comes into contact with an electrolyte solution
Data Source
AI summary
A power storage device a positive electrode including a positive electrode active material layer and a negative electrode including a negative electrode active material layer. The positive electrode active material layer includes a plurality of particles of x[Li2MnO3]-(1−x)[LiCo1/3Mn1/3Ni1/3O2] (obtained by assigning 0.5 to x, for example) which is a positive electrode active material, and multilayer graphene with which the plurality of particles of the positive electrode active material are at least partly connected to each other. In the multilayer graphene, a plurality of graphenes are stacked in a layered manner. The graphene contains a six-membered ring composed of carbon atoms, a poly-membered ring which is a seven or more-membered ring composed of carbon atoms, and an oxygen atom bonded to one or more of the carbon atoms in the six-membered ring and the poly-membered ring, which is a seven or more-membered ring.