Metal-Containing Active Material for Battery Cycle Performance
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Solution Overview
Problem
Conventional metal-containing particles used in electrochemical devices, such as lithium secondary batteries, exhibit poor cycle and rate performance due to issues like poor electric conduction and slow lithium ion diffusion, which are exacerbated by particle expansion and release from the current collector.
Innovation Solution
A production method involving the polymerization of a mixture of a metal ion, hydroxy acid, and polyol to form a metal complex, followed by carbonization, which results in metal-containing particles supported within a carbonaceous porous material, enhancing electrolyte ion diffusion and electron conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If metal-containing particles are used as anode active materials, then charge and discharge capacities are larger than graphite, but cycle performance is considerably poorer
Solution Approach 1:
The invention uses composite materials consisting of metal-containing particles dispersed in a carbonaceous porous material. The carbon matrix provides structural stability and electrical conductivity while the metal particles provide high charge/discharge capacity. This composite structure resolves the contradiction by combining the high capacity of metal particles with the stability of carbon materials.
Solution Approach 2:
The invention employs porous carbonaceous material as the support matrix for metal-containing particles. The porous structure provides adequate space for ion diffusion pathways while maintaining structural integrity during charge-discharge cycles. This prevents particle aggregation and maintains electrical conductivity, thereby improving cycle performance while preserving high capacity.
2Speed
If metal-containing particles are micronized to improve rate performance, then particle size is reduced, but electric conduction fails due to particle expansion and release from current collector
Solution Approach 1:
The porous carbonaceous material serves as a stable support matrix that anchors micronized metal-containing particles. The porous structure provides pathways for rapid ion diffusion (improving rate performance) while the carbon matrix prevents particle release and maintains electrical conductivity (preserving electric conduction).
Solution Approach 2:
The composite structure of metal-containing particles dispersed in carbonaceous material ensures that micronized particles remain electrically connected through the conductive carbon matrix. This prevents the loss of electrical conduction that occurs when particles are released from the current collector, while still achieving fast ion diffusion through the porous structure.
3Power
If metal-containing particles are used, then high charge capacity is achieved, but lithium ion diffusion is slow in solid particles
Solution Approach 1:
The porous carbonaceous material provides interconnected pores that serve as fast diffusion pathways for lithium ions. These pores reduce the diffusion distance and resistance compared to solid particles, enabling rapid ion transport while the metal-containing particles embedded in the porous matrix maintain their high charge capacity.
4Power
If metal-containing particles expand during charge-discharge cycles, then charge capacity is maintained, but particles become more finely powdered and release from current collector
Solution Approach 1:
The carbonaceous porous material acts as a stable matrix that accommodates the expansion and contraction of metal-containing particles during charge-discharge cycles. This composite structure prevents particle pulverization and release from the current collector while maintaining the charge capacity of the metal particles.
Solution Approach 2:
The carbonaceous porous material serves as a cushioning matrix that absorbs the mechanical stress of particle expansion before it causes damage. This prevents the particles from becoming finely powdered and releasing from the current collector, thereby maintaining both charge capacity and particle integrity.
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 method produces active materials with improved cycle and rate performance by maintaining small particle sizes and suppressing thermal expansion, ensuring adequate electron conductivity even with particles of poor conductivity.
Implementation Method 1
the hydroxy acid coordinates around the metal ion to form a metal complex, and the metal ion is readily dispersed in the form of the metal complex in the polyol
Implementation Method 2
When the mixture is polymerized by heating or the like to cause dehydrating condensation (esterification) of the COOH group of the hydroxy acid and each OH group of the polyol, an organic network is formed by the polymer of the polyol and the hydroxy acid
Implementation Method 3
the carbonization of this polymer obtains an active material in which fine metal-containing particles, e.g., with particle diameter of about 10-300 nm are supported in a carbonaceous porous material
Implementation Method 4
Since the particle diameter of the metal-containing particles are sufficiently small in such an active material, diffusion of electrolyte ions is adequately promoted
Data Source
AI summary
A production method of an active material, and the active material are provided to realize an active material containing metal-containing particles and being capable of achieving satisfactory cycle performance and rate performance. The active material is produced by a method of polymerizing a mixture of a metal ion, a hydroxy acid, and a polyol to obtain a polymer, and a step of carbonizing the polymer. The active material used is one having a carbonaceous porous material, and metal particles and/or metal oxide particles supported in pores of the carbonaceous porous material, and particle diameter of the metal-containing particles are in the range of 10 to 300 nm.