Metal Salt Anode Coating for Battery Cycle Stability

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Solution Overview

Problem

Lithium ion secondary batteries face challenges in improving cycle characteristics and preventing swelling due to the decomposition of electrolytic solutions and the use of high-capacity anode materials like silicon, which affects their performance and longevity.

Innovation Solution

A metal salt coat is applied to the anode active material layer on the anode current collector, enhancing the chemical stability of the anode and preventing reactions with the electrolytic solution, thereby improving cycle and swollenness characteristics without requiring special environmental conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-capacity anode materials like silicon are used to improve battery capacity, then the theoretical capacity is significantly improved, but the electrolytic solution is easily decomposed and lithium is easily inactivated, worsening cycle characteristics

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies composite materials by combining silicon anode material with a carbon coating layer. The carbon coating serves as a protective matrix that contains the silicon particles, preventing direct contact between silicon and the electrolytic solution, thereby reducing decomposition while maintaining the high capacity benefits of silicon.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent uses a thin film coating approach where a carbon-based protective layer is applied over the silicon anode material. This thin film acts as a barrier that prevents electrolyte decomposition and lithium inactivation while allowing lithium ion transport, thus improving cycle characteristics without sacrificing capacity.

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If high-capacity anode materials like silicon are used, then the battery capacity is highly improved, but the battery is easily swollen due to gas generated in decomposition of the electrolytic solution, worsening swollenness characteristics

Engineering Contradiction:

Improvebattery capacityVSAvoidswollenness characteristics

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent employs a thin film protective coating that acts as a barrier between the silicon anode and the electrolytic solution. This coating prevents gas generation from electrolyte decomposition, thereby preventing battery swelling while allowing the high-capacity silicon material to function effectively.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent converts the potential harm of silicon reactivity with electrolyte (which causes gas generation and swelling) into a benefit by using the controlled carbon coating to prevent direct contact. The coating transforms the harmful interaction into a protected interface, eliminating swelling while maintaining capacity.

Inventive Principle:

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

3Reliability

If conventional anode materials are used, then the electrolytic solution stability is maintained, but the battery capacity is limited by the lower theoretical capacity compared to silicon

Engineering Contradiction:

Improveelectrolytic solution stabilityVSAvoidbattery capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent creates a composite structure where silicon particles are embedded in a carbon matrix. This composite maintains electrolytic solution stability (as the carbon layer prevents direct silicon-electrolyte contact) while achieving high battery capacity (as the silicon provides high theoretical capacity and the carbon ensures conductivity and structural integrity).

Inventive Principle:

Principle #40Composite materials

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 metal salt coat efficiently facilitates the insertion and extraction of electrode reactants, reduces decomposition, and enhances the battery's cycle and swollenness performance, particularly when using high-capacity anode materials like silicon.

Implementation Method 1

the anode active material inserting lithium in charge and discharge

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 2

the electrolytic solution is easily decomposed

Methodology Applied

Scientific EffectDecomposition: Decomposition (biological)

Data Source

PatentUS8613873B2Anode, battery, and methods of manufacturing them

Publication Date: 2013.12.24 MURATA MFG CO LTD

AI summary

A battery capable of improving the cycle characteristics and the swollenness characteristics is provided. The battery includes a cathode, an anode, and an electrolytic solution. The electrolytic solution is impregnated in a separator provided between the cathode and the anode. The anode has a coat on an anode active material layer provided on an anode current collector. The coat contains a metal salt. The metal salt has a hydroxyl group and at least one of a sulfonic acid group and a carboxylic acid group. Thereby, lithium ions are easily inserted in the anode and extracted from the anode, and decomposition of the electrolytic solution is prevented.