Multi-shell Core-Shell Anode Material for Lithium-Ion Batteries
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Solution Overview
Problem
Current lithium-ion battery anode materials, such as graphite, have limited theoretical specific capacity and suffer from rapid capacity decrease due to volume expansion and contraction during lithiation and delithiation, leading to inadequate cycling stability and efficiency.
Innovation Solution
A multi-composite anode material with a multi-shell core-shell structure is developed, comprising an inner core of graphite coated with nano-active materials, a first shell of electrically conductive carbon, and a second shell of another nano-active material, enhancing electroconductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal elements, metal oxides or metal alloy compounds (such as Si, Sn, Ge, Pb, SiO, SnO, SbSn, Mg2Si) are used as anode materials to increase theoretical specific capacity, then the specific capacity is improved, but the battery capacity decreases rapidly during use due to large volume expansion and contraction
Solution Approach 1:
The patent applies nested structure by placing nano-active material particles inside a hollow carbon sphere shell, creating a core-shell configuration where the active material is enclosed within the carbon matrix. This nested structure allows the active material to expand and contract within the protective carbon shell during lithiation and delithiation, preventing structural damage while maintaining high capacity.
Solution Approach 2:
The patent uses a hollow carbon sphere shell as a flexible container that can accommodate volume changes of the enclosed active material. The carbon shell acts as a buffer that flexibly expands and contracts during charge-discharge cycles, preventing material crushing and maintaining structural integrity, thereby improving cycling stability.
2Stability of the object's composition
If nanocrystallization, alloying or multi-composition methods are used to inhibit volume expansion, then the structural stability is improved, but the continuous phase forms large size and does not homogeneously disperse the components
Solution Approach 1:
The patent applies local quality by creating regions with different functions: the hollow carbon sphere provides structural stability and conductivity, while the nano-active material particles provide high capacity. The nanoscale dimensions of both the hollow spheres and active material particles ensure homogeneous dispersion throughout the electrode matrix, avoiding large continuous phases while maintaining structural integrity.
3Quantity of substance
If nano-silicon powder is used to increase capacity, then the specific capacity is improved, but the initial charge-discharge efficiency is lower due to insufficient dispersion
Solution Approach 1:
The patent creates a composite material system combining hollow carbon spheres with nano-active material particles. The carbon spheres serve as a conductive matrix that enhances electron transport, while the dispersed nano-active material particles provide lithium storage capacity. This composite structure ensures sufficient dispersion of active material, preventing aggregation and improving initial charge-discharge efficiency while maintaining high specific capacity.
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 multi-composite anode material achieves high electroconductivity, high capacity, and excellent cycling performance with a capacity retention ratio of 90% or more after 400 cycles and high initial efficiency, while being environmentally friendly and cost-effective.
Implementation Method 1
the continuous phase formed by silicon and chromium in the ternary material prepared by such process still has a large size, and does not homogeneously disperse copper, chromium and silicon
Implementation Method 2
a first shell of an electrically conductive carbon material, a second shell of a nano-active material, and a third shell of a coating layer for the electrically conductive carbon material
Data Source
AI summary
A multiple-element composite material for negative electrodes, a preparation method therefor, and a lithium-ion battery using the negative electrode material. The lithium-ion battery uses multiple-element composite material for negative electrodes has a core-shell structure containing multiple shell layers. The inner core consists of graphite and nano-active matter coating the surface of the graphite. The outer layers of the inner core are in order: the first shell layer is of an electrically conductive carbon material, the second shell layer is of a nano-active matter, and the third shell layer is an electrically conductive carbon material coating layer. The multiple-element composite material for negative electrodes of the present invention combines coating processing technology with surface composite modification and coating modification technology to successfully prepare a multiple-element composite material for negative electrodes having a core-shell structure containing multiple shell layers, and allows for high load and high dispersion for the nano-active matter, thereby substantially enhancing the material specific capacity, cycle performance, and initial efficiency. Additionally, the multiple-element composite material for negative electrodes of the present invention has high compacted density and good processing performance. The negative electrode material has simple preparation technique and low raw material cost, is environmentally friendly, and causes no pollution.