Pre-Lithiated Silicon Anode Coating for Stable SEI and Cycle Life

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional lithium-ion batteries face challenges with low specific capacity, irreversible capacity loss, and instability due to large volume expansion and SEI film issues, leading to poor cycle life and efficiency, despite the potential of silicon as a negative electrode material.

Innovation Solution

A pre-lithiated silicon negative electrode material coated with a lithium-containing polymer is used to form a stable SEI film, reducing lithium consumption and volume expansion, and a method involving decompression rotary evaporation for efficient preparation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon content in negative electrode is increased to improve battery capacity, then battery capacity increases, but electrode structure stability deteriorates and expansion occurs

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrode structure stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The negative electrode is segmented into multiple functional layers: a protective coating layer containing lithium compounds applied on the silicon-containing electrode surface. This segmentation isolates the silicon expansion issue from the overall electrode structure while maintaining high silicon content for capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The negative electrode uses composite material structure combining silicon-containing material with protective coating materials (lithium compounds such as lithium phosphate, lithium sulfate, lithium selenate). This composite structure provides both high capacity from silicon and structural stability from the protective coating.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon-containing material is used to increase battery capacity, then battery capacity increases, but harmful factors increase due to electrolyte decomposition and binder detachment

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrolyte decomposition and binder detachment

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

A protective coating layer containing lithium compounds is applied in advance on the silicon-containing electrode surface before electrode assembly. This preliminary protective layer prevents electrolyte decomposition and binder detachment that would otherwise occur with silicon expansion.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The protective coating layer converts the harmful expansion effect of silicon into a beneficial mechanism: the controlled decomposition of lithium compounds in the coating layer consumes expansion stress while generating protective lithium fluoride that further stabilizes the electrode structure.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If conventional coating methods are used to apply protective layers, then coating can be applied, but manufacturing complexity increases and coating uniformity is poor

Engineering Contradiction:

Improvecoating application processVSAvoidcoating uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mechanical coating process is replaced with a chemical field method: the electrode is immersed in an aqueous solution containing lithium compound salts, allowing uniform coating through diffusion and precipitation processes rather than mechanical application.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The coating method uses parameter changes in the form of aqueous solution concentration, temperature, and immersion time to control coating thickness and uniformity, replacing complex mechanical coating parameters with simpler solution-based parameters.

Inventive Principle:

Principle #35Parameter changes

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 initial charge/discharge efficiency and cycle performance, with high capacity retention and stability, forming a stable SEI film to prolong battery life.

Implementation Method 1

a decomposition reaction of the lithium compound is promoted during battery operation, thereby expansion of the negative electrode is consumed and lithium fluoride which is an excellent solid electrolyte additive is generated

Methodology Applied

Scientific EffectDecomposition reaction: Decomposition (biological)

Implementation Method 2

forming a protective coating layer by an aqueous solution of a specific lithium compound salt

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentEP4156335B1Pre-lithiated silicon negative electrode material, silicon negative electrode plate, method for preparing same, and lithium-ion battery

Publication Date: 2026.05.06 ZHUHAI COSMX BATTERY CO LTD

Figure 1~2
Figure 3a~3d

AI summary

The present disclosure provides a pre-lithiated silicon negative electrode material, a silicon negative electrode plate, a method for preparing the same, and a lithium-ion battery. The pre-lithiated silicon negative electrode material includes a silicon negative electrode material and a lithium-containing polymer compounded with the silicon negative electrode material. The lithium-containing polymer includes a polymer shown in the following formula 1, where x is 1 to 12, and R1 is I; or II, where y is 1 to 4; or III or IV The use of the pre-lithiated silicon negative electrode material can improve performance, such as initial Coulombic efficiency, of a lithium-ion battery.