Silicon Anode Coating via Hydrosilylation for Lithium Battery Stability

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Solution Overview

Problem

Silicon anode materials in lithium secondary batteries face issues with unstable solid electrolyte interface (SEI) layer formation and rapid volume expansion during charging/discharging, leading to deteriorated electrochemical characteristics and shortened lifespan due to side reactions and internal stress.

Innovation Solution

A composite anode active material is developed, featuring a silicon material with a chemically bonded coating layer composed of a hydrosilylation product of C4-C30 alkene having a terminal —C(═O)OR group, which suppresses side reactions and volume expansion by forming a stable binding with a polymer, enhancing structural stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a silicon material is used as an anode active material, then high energy density is achieved, but an unstable SEI layer is formed and rapid volume expansion occurs during charging/discharging

Engineering Contradiction:

Improveenergy densityVSAvoidelectrochemical characteristics stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A polymer coating layer is introduced as an intermediary between the silicon material and the electrolyte. This coating layer prevents direct contact between the silicon surface and electrolyte, thereby suppressing side reactions and stabilizing the SEI layer formation, while still allowing lithium ion transport

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin polymer coating layer is formed on the silicon material surface. This flexible film accommodates the volume expansion of silicon during lithiation while maintaining structural integrity and preventing pulverization, thus improving reliability without sacrificing energy density

Inventive Principle:

Principle #30Flexible shells and thin films

2Use of energy by moving object

If a silicon material is used as an anode active material, then high energy density is achieved, but rapid volume expansion causes pulverization due to internal stress

Engineering Contradiction:

Improveenergy densityVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The polymer coating layer acts as a flexible shell that can expand and contract with the silicon core during charging/discharging cycles. This flexible confinement prevents structural pulverization while accommodating the inherent volume changes of silicon

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

A composite structure is created by combining silicon material with a polymer coating layer. The composite structure leverages the high energy density of silicon while the polymer component provides structural stability and stress management, resolving the contradiction between energy density and strength

Inventive Principle:

Principle #40Composite materials

3Reliability

If a coating layer is formed on silicon material to suppress side reactions, then electrochemical characteristics are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveelectrochemical characteristicsVSAvoidcoating process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The polymer coating layer is designed to form through self-service mechanisms such as in-situ polymerization or self-assembly processes. The coating material can polymerize directly on the silicon surface under mild conditions, reducing the need for complex multi-step coating processes and equipment

Inventive Principle:

Principle #25Self-service

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 composite anode active material improves the lifespan and durability of lithium secondary batteries by maintaining stable binding between silicon and the polymer, reducing capacity loss and structural destruction during repeated charging/discharging cycles.

Implementation Method 1

the coating layer includes a hydrosilylation product of a C4-C30 alkene having a terminal —C(═O)OR group

Methodology Applied

Scientific EffectHydrosilylation: Chemical Bonding

Implementation Method 2

the coating layer is chemically bonded to the silicon material

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 3

a coating layer that is formed on at least a portion of a surface of the silicon material, wherein the coating layer is chemically bonded to the silicon material

Methodology Applied

Scientific EffectSEI layer formation suppression: Chemical Bonding

Implementation Method 4

may suppress rapid volume expansion that occurs during a charging/discharging process

Methodology Applied

Scientific EffectVolume expansion suppression: Mechanical Force

Data Source

PatentUS10199638B2Composite anode active material, method of preparing the same, and anode and lithium secondary battery including the composite anode active material

Publication Date: 2019.02.05 SAMSUNG ELECTRONICS CO LTD

AI summary

A composite anode active material including: a silicon material and a coating layer formed on at least a portion of a surface of the silicon material, wherein the coating layer is chemically bonded to the silicon material, and wherein the coating layer includes a hydrosilylation product of a C4-C30 alkene having a terminal —C(═O)OR group, wherein R is a hydrogen, a C1-C5 alkyl group, a C2-C6 heteroalkyl group, a C6-C12 aryl group, or a C7-C13 arylalkyl group, each of which except hydrogen is substituted or unsubstituted.