Expanded-Graphite Cathode for High-Power Multivalent Metal Batteries
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Solution Overview
Problem
Current multivalent metal batteries face limitations in discharge voltage profiles, specific capacity, and cycle life due to the use of graphite-based anodes and cathodes, which result in moderate energy density and low power density, and existing supercapacitors have low energy density but high power density, necessitating the development of new cathode materials for improved performance.
Innovation Solution
A multivalent metal-ion battery is designed with an anode containing a multivalent metal alloy and a cathode made of graphite or carbon materials with expanded inter-planar spaces, allowing for reversible deposition and dissolution of metals like Ni, Zn, and Mg, achieving a discharge curve plateau and high specific capacity, and incorporating a network of conductive nano-filaments to enhance metal deposition-dissolution kinetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite-based anodes and cathodes are used in multivalent metal batteries, then the battery structure is simple and manufacturing is easy, but the energy density is moderate and power density is low
Solution Approach 1:
The patent changes the inter-planar spacing parameter of graphite from conventional values to expanded values (greater than 0.37 nm), which fundamentally alters the ion diffusion characteristics and enables higher power density while maintaining graphite-based electrode simplicity
Solution Approach 2:
The patent uses composite electrode structures combining expanded graphite with conductive nano-filaments (carbon nanotubes, graphene) to achieve both high power density and ease of manufacture, as the composite maintains processability while enhancing electrochemical performance
2Ease of manufacture
If graphite-based anodes and cathodes are used in multivalent metal batteries, then the manufacturing process is simple, but the cycle life is limited
Solution Approach 1:
By changing the inter-planar spacing parameter of graphite to expanded values, the patent enables faster and more reversible ion diffusion, which directly improves cycle life while maintaining the simplicity of graphite-based electrode manufacturing
Solution Approach 2:
The composite structure of expanded graphite with conductive nano-filaments provides both mechanical stability for long cycling and efficient ion transport pathways, achieving enhanced reliability without complicating the manufacturing process
3Device complexity
If conventional graphite with standard inter-planar spacing is used, then the cathode structure is compact and simple, but the specific capacity is limited and discharge voltage plateau is not achieved
Solution Approach 1:
The patent changes the inter-planar spacing parameter of graphite from conventional compact values to expanded values, which increases the cathode's specific capacity and enables discharge voltage plateau without significantly increasing structural complexity
Solution Approach 2:
The expanded graphite structure creates porous pathways between graphene layers that facilitate ion diffusion and accommodate higher ion storage capacity, achieving enhanced specific capacity while maintaining a relatively simple cathode architecture
4Power
If supercapacitor technology is used, then power density is high, but energy density is low
Solution Approach 1:
The patent merges battery chemistry (multivalent metal ion insertion/extraction) with supercapacitor physics (fast ion adsorption/desorption on expanded graphite surfaces) to create a hybrid system that delivers both high power density and high energy density
Solution Approach 2:
The composite electrode combining expanded graphite with conductive nano-filaments creates a structure that provides both capacitive energy storage (high power) and battery-like chemical energy storage (high energy), achieving a synergistic effect that surpasses conventional supercapacitors
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 a stable discharge voltage plateau, high specific capacity, and improved cycle life, combining the energy density of lithium-ion batteries with the power density of supercapacitors, while reducing the tendency for internal shorting and enhancing high-rate capability.
Implementation Method 1
a cathode comprising a cathode active layer of a graphite or carbon material having expanded inter-graphene planar spaces... to support reversible deposition and dissolution of a multivalent metal
Implementation Method 2
incorporating a network of conductive nano-filaments to enhance metal deposition-dissolution kinetics
Data Source
AI summary
Provided is a multivalent metal-ion battery comprising an anode, a cathode, and an electrolyte in ionic contact with the anode and the cathode to support reversible deposition and dissolution of a multivalent metal, selected from Ni, Zn, Be, Mg, Ca, Ba, La, Ti, Ta, Zr, Nb, Mn, V, Co, Fe, Cd, Cr, Ga, In, or a combination thereof, at the anode, wherein the anode contains the multivalent metal or its alloy as an anode active material and the cathode comprises a cathode active layer of a graphite or carbon material having expanded inter-graphene planar spaces with an inter-planar spacing d002 from 0.43 nm to 2.0 nm as measured by X-ray diffraction. Such a metal-ion battery delivers a high energy density, high power density, and long cycle life.