Cathode Active Material Coating for Solid-State Battery Interface Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The initial interface resistance in all-solid-state batteries between the cathode active substance and the solid electrolyte material is high, which hinders the performance and durability of the battery.

Innovation Solution

A cathode active material is developed with a strongly basic cathode active substance coated with a layer containing a polyanionic structural part exhibiting acidity, improving the acid-base polarity and electrochemical stability to reduce the initial interface resistance and prevent its increase over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the surface of cathode active substance is covered with LiNbO3, then the initial interface resistance is reduced, but the interface resistance increases with time

Engineering Contradiction:

Improveinitial interface resistanceVSAvoidinterface resistance stability over time

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies composite coating materials comprising Li3PO4 and Li4SiO4 on the cathode active substance surface. This composite structure combines the low initial interface resistance property of Li3PO4 with the high electrochemical stability and reaction inhibition properties of Li4SiO4, achieving both low initial resistance and long-term stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the coating layer by using a specific molar ratio of Li3PO4 to Li4SiO4 (0.1 to 1.0). By adjusting these compositional parameters, the coating achieves optimal balance between initial interface resistance and long-term stability.

Inventive Principle:

Principle #35Parameter changes

2Power

If the surface of cathode active substance is covered with Li3PO4, then the output and capacity are improved, but the interface resistance increases with time

Engineering Contradiction:

Improvebattery output and capacityVSAvoidinterface resistance stability over time

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The patent combines Li3PO4 with Li4SiO4 in a composite coating structure. The Li3PO4 component provides low initial interface resistance and high output characteristics, while the Li4SiO4 component provides reaction inhibition and long-term stability, preventing interface resistance increase over time.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The coating layer is applied locally on the cathode active substance surface with specific compositional gradients. The composite structure creates different functional zones: Li3PO4-rich regions for low initial resistance and Li4SiO4-rich regions for long-term stability.

Inventive Principle:

Principle #3Local quality

3Duration of action of stationary object

If a reaction inhibition portion comprising Li3PO4-Li4SiO4 is formed on LiCoO2, then the interface resistance increase is inhibited, but the initial interface resistance is high

Engineering Contradiction:

Improveinterface resistance stability over timeVSAvoidinitial interface resistance

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent optimizes the molar ratio parameter of Li3PO4 to Li4SiO4 in the range of 0.1 to 1.0. By adjusting this parameter, the coating achieves the right balance between the reaction inhibition capability of Li4SiO4 and the low initial resistance property of Li3PO4.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent controls the coating thickness parameter to be in the range of 1 nm to 500 nm. This thickness optimization ensures sufficient coverage for reaction inhibition while maintaining low initial interface resistance.

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

The cathode active material effectively reduces the initial interface resistance and maintains low resistance over time, enhancing the output characteristics and durability of the all-solid-state battery.

Implementation Method 1

the polarity (acid-base property) between the cathode active substance and the coat layer is so different that affinity at an interface of both is improved to allow interface resistance to be reduced

Methodology Applied

Scientific EffectAcid-base interaction:

Implementation Method 2

the coat layer provided with a polyanionic structural part high in electrochemical stability is formed so as to cover the cathode active substance, so that a reaction between the coat layer and the cathode active substance and the solid electrolyte material may be inhibited

Methodology Applied

Scientific EffectElectrochemical stability:

Data Source

PatentUS9537137B2Cathode active material, cathode active material layer, all solid state battery and producing method for cathode active material

Publication Date: 2017.01.03 TOYOTA JIDOSHA KK

AI summary

The main object of the present invention is to provide a cathode active material capable of reducing the initial interface resistance against a solid electrolyte material. The present invention solves the above-mentioned problems by providing a cathode active material comprising a cathode active substance exhibiting strong basicity and a coat layer formed so as to cover the surface of the above-mentioned cathode active substance and provided with a polyanionic structural part exhibiting acidity.