Silicon Oxide Anode Coating for Moisture-Stable Li-Ion Batteries
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Solution Overview
Problem
Existing negative electrode active materials, particularly silicon-based oxides, face challenges such as high irreversible capacity, volume expansion/contraction, and poor aqueous processability due to reactivity with moisture, leading to decreased efficiency and stability of lithium secondary batteries.
Innovation Solution
A negative electrode active material is developed, comprising a silicon-based particle with SiOx (0<x<2) and a Li compound, coated with a carbon layer and a surface layer containing Li, Al, and P, with an oxide such as ZrO2 at the interface between the silicon-based particle and the carbon layer, to enhance phase stability and charging/discharging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal doping is applied to silicon-based oxide to reduce irreversible capacity, then initial efficiency is improved, but metal oxide reacts with moisture to increase pH and change viscosity of slurry
Solution Approach 1:
A surface layer comprising Li, Al, and P is introduced as an intermediary between the metal-doped silicon-based oxide particle and the external environment. This surface layer acts as a protective barrier that prevents direct contact between moisture and the reactive metal-doped core, thereby eliminating the harmful reaction while preserving the beneficial electrochemical properties.
Solution Approach 2:
The invention creates a composite structure consisting of a metal-doped silicon-based oxide core surrounded by a Li-Al-P surface layer. This composite design combines the high capacity benefits of metal doping with the stability and low reactivity of the protective surface layer, resolving the contradiction between initial efficiency improvement and moisture reactivity.
2Quantity of substance
If silicon-based oxide is used as negative electrode active material, then capacity is higher than carbon-based materials, but volume expansion/contraction is high and irreversible capacity is high
Solution Approach 1:
A carbon layer is formed on the surface of the silicon-based oxide particle, creating a flexible protective shell. This carbon shell accommodates volume changes during lithium insertion/extraction cycles, preventing structural collapse and reducing irreversible capacity loss while maintaining the high capacity advantage of silicon-based materials.
Solution Approach 2:
The invention creates a composite structure with silicon-based oxide core and carbon shell, combining the high capacity of silicon with the volume stability and conductivity of carbon. This composite design resolves the contradiction between high capacity and volume stability.
3Reliability
If metal-doped silicon-based oxide is used in negative electrode slurry, then irreversible capacity is reduced, but charging and discharging efficiency is lowered due to poor electrode state
Solution Approach 1:
The invention creates a composite structure with metal-doped silicon-based oxide core, carbon shell, and Li-Al-P surface layer. This multi-layer composite optimizes both initial efficiency (through metal doping) and charging/discharging efficiency (through carbon shell conductivity and surface layer stability), resolving the contradiction between these two performance parameters.
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 solution improves the discharge capacity, initial efficiency, resistance performance, and life characteristics of lithium secondary batteries by reducing reactivity with water, stabilizing the electrode state, and enhancing lithium diffusion resistance.
Implementation Method 1
coated with a carbon layer and a surface layer containing Li, Al, and P
Implementation Method 2
an oxide such as ZrO2 at the interface between the silicon-based particle and the carbon layer, to enhance phase stability and charging/discharging efficiency
Implementation Method 3
enhancing lithium diffusion resistance
Data Source
AI summary
The present disclosure relates to a negative electrode active material, a negative electrode including the same, a secondary battery including the negative electrode, and a method for manufacturing a negative electrode active material. The negative electrode active material includes a silicon-based particle including SiOx (0<x<2) and a Li compound, a carbon layer provided on at least a portion of a surface of the silicon-based particle, and a surface layer provided on at least a portion of a surface of the carbon layer and comprising Li, Al and P, wherein an oxide comprising one or more selected from the group consisting of Zr, B, Al, Zn, W and Ti is provided at an interface between the silicon-based particle and the carbon layer.