Cage-Structure Anode Material for Stable High-Capacity Batteries
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Solution Overview
Problem
Current negative electrode active materials for secondary batteries, such as those containing Sn, are heavy and costly, making them unsuitable for mobile applications like electric cars, and face challenges in volume changes during charge and discharge cycles.
Innovation Solution
An intermetallic compound with a cage structure comprising a zirconium atom as the central atom and 8-16 silicon atoms as the surrounding atoms, which is lightweight, inexpensive, and capable of stable lithium ion insertion and desorption, is used as the negative electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermetallic compound containing Sn as a major component is used as a negative electrode active material, then the battery exhibits good electrochemical performance with small volume changes during charge and discharge, but the battery weight increases and manufacturing cost rises
Solution Approach 1:
The invention changes the compositional parameters by replacing Sn with Si and adjusting the atomic ratios to achieve a lightweight intermetallic compound with formula ZrxNi1-xSiy where 0.4<x<0.6 and 2<y<4, maintaining electrochemical performance while reducing weight
Solution Approach 2:
The invention uses abundant and inexpensive elements (Zr, Ni, Si) to replace rare and costly Sn, creating a cost-effective negative electrode material that achieves comparable or superior performance without relying on expensive rare elements
2Quantity of substance
If an alloy-type material containing Si is used as a negative electrode active material to achieve high theoretical capacity density, then the battery energy density increases, but the material undergoes great volume changes during charge and discharge
Solution Approach 1:
The invention creates a composite intermetallic compound combining Zr, Ni, and Si in specific ratios, forming a new material phase that integrates the high capacity benefits of Si with the structural stability of intermetallic compounds, achieving both high capacity density and volume stability
Solution Approach 2:
The invention optimizes the atomic ratio parameters (0.4<x<0.6 and 2<y<4) to achieve the optimal balance between capacity density and volume stability, where the specific composition range maximizes lithium insertion capacity while minimizing expansion during cycling
3Quantity of substance
If an intermetallic compound with cage structure containing Zr and Si is used as a negative electrode active material, then the battery achieves high capacity density of 100 mAh/g or more, but the structural complexity increases
Solution Approach 1:
The invention introduces local cage structures within the intermetallic compound where Si atoms form tetrahedral cages around Zr atoms, creating localized regions of high lithium insertion capacity while maintaining overall compositional simplicity and processability
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
This configuration provides a high capacity density of 100 mAh/g or more, enhancing the battery's stability and reducing deterioration in charge-discharge cycles, making it suitable for mobile applications.
Implementation Method 1
an intermetallic compound having a cage structure and containing Sn as a major component undergoes small changes in volume associated with insertion and desorption of lithium ions
Data Source
AI summary
A negative electrode active material for a secondary battery includes an intermetallic compound having a cage structure. The cage structure is constituted of at least one first atom located within a cage, and a plurality of second atoms arranged in a cage-like form so as to surround the first atom. The first atom is a zirconium atom, and the plurality of the second atoms include 8 or more and 16 or less silicon atoms.