Alkali Metavanadate Negative Electrode for High-Capacity Lithium Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries face limitations in capacity, energy density, stability, and safety due to the use of carbon-based negative electrodes, which suffer from low theoretical maximum capacity, lithium precipitation, and potential for ignition and explosion, while alternative alloy-based materials have poor lifespan characteristics.
Innovation Solution
A negative electrode active material comprising 50 wt % or more of alkali metavanadate with a composition of AVO3, where A is an alkali metal, which undergoes amorphization during charging, allowing for high reversible capacity and energy density without the limitations of conventional transition metal oxide-based materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon based compounds are used as negative electrode active material, then reversible intercalation and elimination of lithium ions is achieved with structural and electrical properties maintained, but theoretical maximum capacity is limited to 372 mAh/g
Solution Approach 1:
The patent changes the chemical composition parameter from carbon-based compounds to alkali metavanadate (AVO3) with specific crystal structures (monoclinic, triclinic, or amorphous). This material substitution enables a theoretical maximum capacity exceeding 1000 mAh/g while maintaining reversible lithium ion intercalation and elimination, thus resolving the capacity limitation of carbon-based materials.
2Power
If charge current is increased to achieve high output, then power delivery is improved, but lithium precipitation due to overpotential is caused and capacity reduction occurs
Solution Approach 1:
The patent changes the electrode material parameter from carbon-based compounds to alkali metavanadate (AVO3), which has different electrochemical properties including lower operating voltage and different overpotential characteristics. This material substitution reduces lithium precipitation even at high charge currents, maintaining both high power output and capacity stability.
3Quantity of substance
If alloy based negative electrode materials such as silicone, germanium, tin, or aluminum are used, then theoretical maximum capacity is significantly increased, but volume change during charge and discharge causes poor lifespan characteristics
Solution Approach 1:
The patent changes the material composition parameter from alloy-based materials (silicone, germanium, tin, aluminum) to alkali metavanadate (AVO3) with specific crystal structures. This substitution maintains high theoretical maximum capacity exceeding 1000 mAh/g while significantly reducing volume change during charge and discharge cycles, thereby achieving both high capacity and long lifespan characteristics.
4Quantity of substance
If lithium is charged beyond acceptable amount due to overcharge, then energy storage is increased, but temperature is elevated and exothermic reaction is caused leading to ignition and explosion
Solution Approach 1:
The patent changes the negative electrode material parameter from conventional carbon-based or alloy-based materials to alkali metavanadate (AVO3). This material has different thermodynamic properties and reaction characteristics that reduce the risk of exothermic reactions and ignition even when lithium is charged beyond acceptable amounts, thereby enabling higher energy storage with improved safety.
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 alkali metavanadate-based negative electrode material achieves a reversible capacity of 400 mAh/g or more, improved energy density, and enhanced stability, with a linear voltage-to-capacity relationship for accurate state-of-charge estimation, addressing the limitations of existing materials.
Implementation Method 1
the alkali metavanadate has a crystalline phase or an amorphous phase... which undergoes amorphization during charging
Implementation Method 2
in which reversible intercalation and elimination of lithium ions are possible
Implementation Method 3
negative electrode active material including 50 wt % or more of alkali metavanadate... achieves a reversible capacity of 400 mAh/g or more
Data Source
AI summary
Disclosed are a high-capacity negative electrode active material and a lithium secondary battery including the same. More particularly, the negative electrode active material includes 50 wt % or more of an alkali metavanadate based on the total weight of a negative electrode active material, wherein the alkali metavanadate has a crystalline phase or an amorphous phase, and a composition of formula AVO3.