Negative Electrode Composite Material for Lithium-Ion Batteries
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Solution Overview
Problem
Existing negative electrode materials for lithium-ion batteries, such as tin-based materials, face issues with high volume variations leading to mechanical instability, irreversible capacitance loss, and low cyclability, limiting their performance compared to carbon-based anodes.
Innovation Solution
A negative electrode material comprising an active phase of Al, Si, Sn, or Sb combined with a support phase of XaYbOc, where X and Y form an interface that absorbs volumetric variations, enhancing adhesion and cyclability, and is produced through a method involving mixing oxide precursors, heat treatment, and grinding to create a mixed composition interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If tin-based materials are used to increase capacitance, then gravimetric and volumetric capacitances are improved, but volume variations exceed 100% causing mechanical instability
Solution Approach 1:
The patent uses a composite material consisting of tin particles dispersed in a glass matrix (TCO). The glass matrix provides mechanical stability and constraints on volume expansion, while the tin particles provide high capacitance. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent creates local regions with different properties: tin-rich active centers for electrochemical activity and glass matrix regions for mechanical stability. The heterogeneous structure allows different parts of the material to fulfill different functions, resolving the contradiction between high capacitance and mechanical stability.
2Stability of the object's composition
If TCO materials are used to improve mechanical stability, then volume variations are limited, but irreversible capacitance loss of about 400 mAh/g occurs during first discharge
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass matrix (ratios of oxides such as B2O3, SiO2, P2O5, and metal oxides) to optimize both mechanical stability and electrochemical reversibility. By adjusting these parameters, the material achieves lower irreversible capacitance loss while maintaining structural stability.
Solution Approach 2:
The patent creates a stable glass matrix structure that replicates and maintains its configuration through multiple charge-discharge cycles, providing a consistent framework that prevents degradation and reduces irreversible losses over time.
3Quantity of substance
If TCO materials are used to achieve high gravimetric capacitance, then capacitance reaches 600 mAh/g, but cyclability is low compared to carbon-based anodes
Solution Approach 1:
The glass matrix acts as a pre-prepared cushioning framework that anticipates and accommodates volume changes during lithium insertion/extraction. This pre-existing stable structure prevents mechanical degradation that would otherwise occur during cycling, thereby improving cyclability while maintaining high capacitance.
Solution Approach 2:
The glass matrix serves as an intermediary between the tin particles and the external environment, mediating the mechanical stresses and protecting the tin particles from aggregation. This intermediary structure enables the tin particles to maintain their high capacitance properties while improving overall cyclability.
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 material achieves higher gravimetric and volumetric capacitances than graphite, with improved reversibility, low first cycle capacitance loss, and excellent cyclability, enhancing the performance of lithium-ion batteries while being cost-effective and environmentally friendly.
Implementation Method 1
these wide variations in volume, greater than 100%, due to the reactions associated with the intercalation and deintercalation
Implementation Method 2
production method involving mixing oxide precursors, heat treatment, and grinding
Data Source
AI summary
A negative electrode material, a method for producing this material, and to a negative electrode and a lithium-ion battery comprising this material are described. The material comprises an active phase consisting of a material M based on Al, Si, Sn, Sb or a mixture thereof, and a support phase consisting of a material XaYbOc, where: O is an oxygen; Y is a cation with oxidation degree m=3, 4, 5 or 6; X is a cation with oxidation degree d=1, 2, 3, 4 or 5, X ensuring the electroneutrality of XaYbOc; and where: c is such that 2≦c≦10; b is such that 1≦b≦4; and a=(2c−bm)/d. An interface of mixed composition exists between the XaYbOc material and the active phase M, the interface consisting of the elements M, X, Y and O.