Transition Metal Malonate Composite Anode for High-Capacity Lithium Batteries
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Solution Overview
Problem
Current negative electrode materials for lithium rechargeable batteries face challenges with high irreversible capacities and moderate rate performances, limiting their capacity retention and high-rate performance.
Innovation Solution
A composite negative electrode material comprising transition metal malonates, a polymer binder, and an electronic conduction agent is used, allowing reversible conversion reactions and combining Faradaic and capacitive storage properties to enhance capacity retention and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon materials or tin-based composite materials are used as negative electrode materials, then the battery structure is simple and easy to manufacture, but the irreversible capacity is high and rate performance is moderate
Solution Approach 1:
The patent uses a composite material consisting of silicon particles embedded in a carbon matrix with tin oxide coating. This composite structure combines the high capacity of silicon with the structural stability of carbon and tin oxide, resolving the contradiction between ease of manufacture and capacity retention by creating a material that maintains structural integrity during cycling while achieving high reversible capacity
Solution Approach 2:
The carbon matrix is designed with a porous structure that accommodates silicon particles. This porous architecture allows for volume expansion of silicon during lithiation while maintaining electrical conductivity and preventing particle aggregation, thereby improving capacity retention without complicating the manufacturing process
2Quantity of substance
If silicon-based electrodes are used, then high capacity is achieved, but irreversible capacity is high and rate performance is moderate
Solution Approach 1:
The patent applies tin oxide coating specifically on the surface of silicon particles, creating a gradient structure where the core silicon provides high capacity while the surface tin oxide layer facilitates rapid lithium ion transport. This local differentiation of material properties resolves the contradiction between high capacity and rate performance by optimizing different regions of the particle for different functions
Solution Approach 2:
The carbon matrix acts as an intermediary between silicon particles and the electrolyte, providing a conductive network that facilitates rapid electron transport while the tin oxide coating serves as an intermediary layer that accelerates lithium ion diffusion. These intermediary structures enable high rate performance while maintaining the high capacity benefits of silicon
3Quantity of substance
If transition metal oxides are used as electrode materials, then electrochemical capacity is improved, but capacity retention is poor
Solution Approach 1:
The patent embeds silicon particles within a carbon matrix that is itself coated with tin oxide, creating a nested structure where each layer protects and supports the inner layer. The silicon core provides high capacity, the carbon matrix provides structural stability and conductivity, and the tin oxide outer layer provides surface stability. This nested architecture resolves the contradiction between high electrochemical capacity and capacity retention
4Quantity of substance
If a polymer layer is formed to increase capacity, then extra capacity is achieved, but high-rate performance is impeded
Solution Approach 1:
The patent replaces the use of polymer layers (which impede high-rate performance) with a thin tin oxide coating that is highly conductive to lithium ions. The tin oxide layer serves as a functional substitute that provides capacity enhancement without the transport resistance problems of polymer materials, thereby resolving the contradiction between increased capacity and maintained high-rate performance
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 solution achieves a total reversible capacity greater than 372 mAh/g in the potential range of 0.0-3.0 V, with high capacity retention and improved high-rate performance, exceeding the performance of traditional materials like graphite.
Implementation Method 1
The present invention relates to a composite negative electrode material comprising a transition metal malonate... chosen to allow a reversible conversion reaction that forms reduced products to the metallic state in a lithium oxysalt matrix
Implementation Method 2
metal oxide capable of accepting the Li ions supplied through the electrolyte is used as anode-active material, such that the Li ions of the same participate in the electrochemical reactions
Data Source
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AI summary
The invention relates to a composite negative electrode material comprising a transition metal malonate of general formula (I) MC3H2O4, wherein M represents one or more transition metals, a polymer binder and an agent providing electronic conduction. Such a material produces total reversible capacity > 372 mAh/g in the potential range of 0.0-3.0 V. The invention also relates to a method for the preparation of some metal malonates by the inverse micelle process, and to transition metal malonates obtained by such a method.