Silicon Oxide Anode Skeleton Coating for Low-Gas Pre-Lithiation
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Solution Overview
Problem
Silicon-based negative electrode materials for lithium-ion batteries face challenges such as high expansion, violent volume change, and low first efficiency due to uncontrolled pH and gas generation during the pre-lithiation process, leading to decreased battery capacity and electrode quality.
Innovation Solution
A negative electrode material is developed with a skeleton structure comprising lithium silicate and water-insoluble silicate, where the water-insoluble silicate is coated on the surface of lithium silicate, and a silicon oxygen material is embedded within, forming a heterojunction interface that inhibits gas generation and improves processability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pre-lithiation process is applied to improve first efficiency of silicon-based negative electrode material, then first efficiency is improved, but gas generation and active silicon loss occur due to uncontrolled pH
Solution Approach 1:
A water-insoluble silicate coating layer is introduced as an intermediary between the lithium silicate and the external environment. This coating layer acts as a barrier that prevents water from contacting the alkaline lithium silicate, thereby eliminating the harmful gas generation while preserving the beneficial pre-lithiation effects. The coating layer mediates the interaction between the active material and water, allowing the system to achieve both high first efficiency and low gas generation.
Solution Approach 2:
A thin film coating of water-insoluble silicate is applied to the surface of the silicon-based material. This thin film serves as a protective shell that controls the interaction between the internal alkaline lithium silicate and external water. The coating is sufficiently thin to allow lithium ion transport while being impermeable to water molecules, thus preventing gas generation without compromising the pre-lithiation functionality.
2Productivity
If pre-lithiation process is applied to improve first efficiency, then first efficiency is improved, but active silicon is lost and becomes inactive silicon, resulting in decreased battery capacity
Solution Approach 1:
The water-insoluble silicate coating acts as a protective intermediary that prevents oxidizing agents in the electrolyte from contacting and oxidizing the active silicon. By blocking this harmful interaction, the coating preserves the active silicon content while allowing the pre-lithiation process to proceed, thus maintaining both high first efficiency and adequate battery capacity.
Solution Approach 2:
The patent converts the potentially harmful oxidation reaction into a beneficial process by controlling where and how it occurs. The water-insoluble silicate coating directs the oxidation to occur only at the coating surface rather than consuming active silicon, thereby transforming what would be a capacity-reducing side reaction into a controlled surface phenomenon that does not affect the active material.
3Object-generated harmful factors
If water-insoluble silicate coating is applied to block water contact, then gas generation is reduced, but processability may be affected
Solution Approach 1:
The patent optimizes the thickness and composition parameters of the water-insoluble silicate coating to achieve a balance between gas generation reduction and processability. By carefully controlling the coating thickness and silicate composition, the material maintains good dispersibility and processability while effectively preventing water contact with the alkaline lithium silicate.
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 solution effectively blocks water contact with alkaline lithium silicate, reduces gas generation, and enhances electrochemical performance, leading to improved lithium ion transfer capacity and prolonged battery service life while maintaining low production costs.
Implementation Method 1
a skeleton of water-insoluble silicate located on a surface layer of the active material... the skeleton of water-insoluble silicate is linked with the skeleton of lithium silicate
Implementation Method 2
water-insoluble silicate... blocks water contact with alkaline lithium silicate
Implementation Method 3
The lithium silicate can be used as a buffer zone in a charging and discharging expansion process
Implementation Method 4
due to a high lithium content of interface thereof, the lithium silicate can also be used as fast ion conductor to accelerate rapid transfer of lithium ions inside
Implementation Method 5
forming a heterojunction interface that inhibits gas generation and improves processability and cycle performance
Data Source
AI summary
The present disclosure relates to a negative electrode material and a preparation method thereof and a lithium ion battery, wherein the negative electrode material includes an active material, the active material includes a skeleton structure and a silicon oxygen material embedded on the skeleton structure; the skeleton structure includes a skeleton of lithium silicate located inside the active material and a skeleton of water-insoluble silicate located on a surface layer of the active material, and the skeleton of water-insoluble silicate is linked with the skeleton of lithium silicate, wherein in an XRD pattern of the negative electrode material, an intensity of a strongest diffraction characteristic peak of the lithium silicate is IA, and an intensity of a strongest diffraction characteristic peak of the water-insoluble silicate is IB, and 0.03≤IB/IA≤0.2.