Silicon Anode Core-Shell Coating for Lithium Battery Stability
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Solution Overview
Problem
Lithium ion batteries using silicon or silicon alloys as anode active materials face challenges due to significant volume changes during charge and discharge, leading to capacity loss and low electrical conductivity, necessitating an improvement in charge-discharge rate and lifetime characteristics.
Innovation Solution
An anode active material is developed with a core that incorporates lithium ions, featuring multiple coating layers composed of metal oxides and amorphous carbonaceous materials, which are thermally treated to enhance lithium ion diffusion and suppress side reactions with the electrolyte, thereby improving the battery's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon or silicon alloys are used as anode active materials to achieve high capacity, then the energy density is improved, but the volume change during charge and discharge causes capacity loss and reduces lifetime
Solution Approach 1:
The patent employs a core-shell structure where the silicon core is nested within a protective coating shell. The core contains the high-capacity silicon material while the shell provides structural stability and prevents volume expansion, allowing the inner core to expand and contract during lithiation/delithiation without compromising the overall electrode integrity.
Solution Approach 2:
The patent uses composite materials combining silicon with carbonaceous materials and metal oxides in a core-shell configuration. This composite structure leverages the high capacity of silicon while the carbon and metal oxide components provide mechanical stability, electrical conductivity, and protection against electrolyte degradation, resolving the contradiction between high energy density and capacity retention.
2Use of energy by moving object
If silicon or silicon alloys are used as anode active materials to achieve high capacity, then the energy density is improved, but the electrical conductivity remains low
Solution Approach 1:
The patent creates a composite structure where silicon cores are combined with conductive carbonaceous materials and metal oxides. The carbon and metal oxide components form conductive networks that facilitate electron transport, while the porous structure provides ion diffusion pathways, thereby improving charge-discharge rate without sacrificing the high capacity benefit of silicon.
Solution Approach 2:
The patent employs porous carbonaceous materials and metal oxide structures that provide extensive surface area and interconnected pore networks. These porous structures facilitate rapid lithium ion diffusion to the silicon cores while the carbon matrix maintains electrical conductivity, enabling high rate performance despite silicon's inherently low conductivity.
3Quantity of substance
If the core surface is exposed to electrolyte during volume change, then charge capacity is improved, but side reactions increase and reduce lifetime
Solution Approach 1:
The patent uses a nested core-shell structure where the silicon core is enclosed within a protective coating shell made of carbonaceous materials and metal oxides. This nesting allows the core to undergo volume changes and accommodate lithium ions while the outer shell acts as a stable interface with the electrolyte, preventing direct exposure of the core surface and minimizing side reactions.
Solution Approach 2:
The patent introduces carbonaceous materials and metal oxides as intermediary layers between the silicon core and the electrolyte. These intermediary materials serve as stable interfaces that facilitate lithium ion transport while preventing direct contact between the reactive silicon surface and the electrolyte, thereby suppressing side reactions and improving battery lifetime.
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 anode active material enhances the charge-discharge rate and lifetime characteristics of lithium batteries by effectively managing volumetric expansion and preventing electrolyte exposure, resulting in improved capacity retention and electrical conductivity.
Implementation Method 1
thermally treating the first mixture in an inert atmosphere to form a first coating layer on a surface of the core
Implementation Method 2
thermally treating the second mixture to form a second coating layer on the first coating layer
Implementation Method 3
a core including a metal or a metalloid that can incorporate and deincorporate lithium ions
Data Source
AI summary
An anode active material includes: a core including a metal or a metalloid that can incorporate and deincorporate lithium ions; and a plurality of coating layers on a surface of the core, each coating layer including a metal oxide, an amorphous carbonaceous material, or combination thereof. Also, a lithium battery including the anode active material, and a method of preparing the anode active material.