Silicon Oxide Anode Coating for Slurry-Stable Li-Ion Batteries
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Solution Overview
Problem
Silicon-based oxide negative electrode active materials in lithium secondary batteries suffer from low initial efficiency due to high irreversible capacity and volume expansion, and metal-doped versions react with moisture, affecting slurry viscosity and charge/discharge efficiency.
Innovation Solution
A negative electrode active material comprising silicon-based particles coated with a first carbon layer, a composite layer of Li, M, P, and O elements, and a second carbon layer, where M is Al, B, or Zn, with a D/G band ratio of 1.0 or more, formed through specific chemical processes to stabilize the slurry and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal doping is applied to silicon-based oxide to reduce irreversible capacity, then initial efficiency is improved, but the metal oxide reacts with moisture to increase pH and change viscosity of the slurry, deteriorating electrode state and charge/discharge efficiency
Solution Approach 1:
A coating layer comprising Li, M, P, and O elements (where M is Al, B, or Zn) is formed on the surface of the silicon-based oxide particles. This coating layer acts as an intermediary barrier that prevents direct contact and reaction between the metal-doped silicon-based oxide and moisture in the slurry, thereby maintaining slurry stability while preserving the improved initial efficiency benefits of metal doping
Solution Approach 2:
The invention creates a composite structure by combining silicon-based oxide particles with a coating layer containing Li, M, P, and O elements. This composite material approach allows the core silicon-based oxide to provide high capacity while the coating layer provides protection against moisture reaction, simultaneously achieving improved initial efficiency and maintained slurry stability
2Quantity of substance
If silicon-based oxide is used as negative electrode active material, then high capacity is achieved, but volume expansion during charging/discharging causes large irreversible capacity and low initial efficiency
Solution Approach 1:
A thin coating layer comprising Li, M, P, and O elements is formed on the surface of the silicon-based oxide particles. This thin film structure accommodates the volume expansion and contraction of the silicon-based oxide during charging and discharging while maintaining structural integrity, reducing irreversible capacity loss and improving initial efficiency without sacrificing the high capacity benefits
Solution Approach 2:
The invention creates a composite structure combining silicon-based oxide core with a protective coating layer containing Li, M, P, and O elements. This composite design allows the core to provide high capacity through lithium alloying reactions while the coating layer provides mechanical stability during volume changes, simultaneously achieving high capacity and improved initial efficiency
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
Improves discharge capacity, initial efficiency, resistance performance, and service life characteristics of the battery by stabilizing the electrode slurry and reducing volume expansion.
Implementation Method 1
the first carbon layer, a composite layer of Li, M, P, and O elements, and a second carbon layer, where M is Al, B, or Zn
Implementation Method 2
with a D/G band ratio of 1.0 or more, formed through specific chemical processes to stabilize the slurry and enhance conductivity
Implementation Method 3
there is a problem in that the metal oxide formed by doping the metal reacts with moisture to increase the pH of the negative electrode slurry
Implementation Method 4
the silicon-based active material has a disadvantage in that the initial efficiency is low because the degree of volume expansion/contraction due to charging/discharging is large and the irreversible capacity is large
Data Source
AI summary
The present invention relates to a negative electrode active material, a negative electrode including the same, a secondary battery including the same and a method for preparing the negative electrode active material.