Amorphous Li-Si Anode Cladding for Stable Solid-State Cycling
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Solution Overview
Problem
Existing silicon negative electrode materials in all-solid-state lithium batteries undergo significant volumetric changes during lithium intercalation/deintercalation, leading to rapid capacity decline and poor cycling performance, along with poor contact issues that increase impedance.
Innovation Solution
A negative electrode material comprising a core of glassy solid electrolyte with dispersed amorphous lithium-silicon alloy particles, clad with an amorphous lithium-silicon alloy layer, which reduces volumetric expansion and enhances contact performance, thereby improving cycling stability and electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon negative electrode material is used in all-solid-state lithium batteries, then high theoretical specific capacity is achieved, but huge volumetric changes occur during lithium intercalation/deintercalation leading to rapid capacity decline
Solution Approach 1:
The patent embeds silicon-based negative electrode particles within a porous carbon matrix, creating a nested structure where the carbon matrix acts as a protective container. This nested configuration allows the silicon particles to undergo volumetric changes during lithium intercalation/deintercalation while the outer carbon matrix maintains structural integrity, preventing capacity decline and improving cycling performance.
Solution Approach 2:
The patent employs a porous carbon matrix as a flexible shell surrounding the silicon-based particles. This carbon shell is designed with sufficient porosity and mechanical flexibility to accommodate the huge volumetric changes of silicon during lithium insertion/extraction cycles, thereby preventing particle fracture and maintaining electrochemical performance over extended cycling.
2Quantity of substance
If silicon negative electrode material is used, then high theoretical specific capacity is achieved, but poor contact between particles occurs leading to increased impedance
Solution Approach 1:
The porous carbon matrix serves as a conductive network that ensures good contact between silicon-based particles and the electrolyte. The carbon shell maintains intimate particle contact while its porous structure allows electrolyte penetration, thereby reducing impedance without compromising the high capacity of silicon.
Solution Approach 2:
The patent creates a composite material system combining silicon-based particles with porous carbon matrix. This composite structure leverages the high capacity of silicon while the carbon component provides electrical conductivity and mechanical stability, ensuring good particle contact and low impedance during battery operation.
3Quantity of substance
If silicon negative electrode material is used, then high theoretical specific capacity is achieved, but rapid capacity decline occurs due to volumetric expansion
Solution Approach 1:
By nesting silicon particles within a porous carbon matrix, the invention protects the silicon from structural degradation during repeated lithium insertion/extraction. The carbon matrix absorbs and distributes the mechanical stress from volumetric expansion, preventing particle fracture and maintaining capacity over long cycle life.
Solution Approach 2:
The porous carbon matrix acts as a flexible protective shell that can expand and contract with the silicon particles during cycling. This flexible containment prevents the rapid capacity decline observed in pure silicon electrodes by maintaining structural integrity over hundreds of charge-discharge cycles.
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 proposed negative electrode material exhibits improved cycling stability, reduced impedance, and superior electrochemical properties, resulting in higher capacity and better performance for all-solid-state lithium batteries.
Implementation Method 1
the glassy solid electrolyte serves as the skeleton for the core to support and disperse the amorphous lithium-silicon alloy particles and buffer the volumetric expansion of the amorphous lithium-silicon alloy particles
Implementation Method 2
the outermost layer is the amorphous lithium-silicon alloy layer, so that the contact performance between the negative electrode material is good, which facilitates reducing the impedance
Implementation Method 3
the amorphous lithium-silicon alloy particles are dispersed in the glassy solid electrolyte to serve as the core... in the process of lithium intercalation/deintercalation
Data Source
AI summary
The present disclosure provides a negative electrode material, a preparation method thereof, and an all-solid-state lithium battery. The negative electrode material includes a core and an amorphous lithium-silicon alloy layer cladding the core. The core includes a glassy solid electrolyte and amorphous lithium-silicon alloy particles dispersed in the glassy solid electrolyte. The material of the amorphous lithium-silicon alloy particles is LixSi, 0<x≤4.4. The material of the amorphous lithium-silicon alloy layer is LiySi, 0<y≤4.4.