Solid Electrolyte Composition for Higher Ion Conductivity

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Solution Overview

Problem

Existing all-solid-state batteries require improved ion conductivity and cycle characteristics in their solid electrolytes.

Innovation Solution

A solid electrolyte with a specific composition ratio of PO4 in the range of 2.600 or more and 2.800 or less, represented by LiM2(PO4)z, where M includes elements with valences of one to four, enhances ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphate compounds with NASICON-type crystal structure (LiM2(PO4)3) are used as solid electrolyte, then the battery structure is established, but the ion conductivity is insufficient for improved cycle characteristics

Engineering Contradiction:

Improvecycle characteristicsVSAvoidion conductivity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the stoichiometric parameters of the solid electrolyte by controlling the molar ratios of Li2SiO3 (0.2-0.8), SiO2 (0.1-0.5), and P2O5 (0.1-0.5) to achieve optimal ion conductivity while maintaining NASICON-type crystal structure, directly resolving the contradiction between reliability and ion conductivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite solid electrolyte system by combining Li2SiO3, SiO2, and P2O5 in specific proportions, forming a composite material that achieves both the required structural stability for reliability and enhanced ion conductivity through synergistic effects of the components

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If substitution of M with monovalent to trivalent elements is performed to improve ion conductivity, then ion conductivity increases, but the proportion of PO4 becomes small compared to traditional NASICON structure

Engineering Contradiction:

Improveion conductivityVSAvoidPO4 proportion

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent optimizes the compositional parameters by maintaining PO4 proportion within 0.1-0.5 molar ratio while adjusting Li2SiO3 and SiO2 content to achieve high ion conductivity without compromising the structural stability provided by adequate PO4 content

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality modification by introducing specific amounts of SiO2 and P2O5 at controlled positions in the crystal structure, allowing ion conductivity enhancement in specific regions while maintaining overall compositional stability through balanced PO4 distribution

Inventive Principle:

Principle #3Local quality

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 improved ion conductivity results in better cycle characteristics for the all-solid-state battery, enhancing its performance.

Implementation Method 1

improving the ion conductivities of solid electrolytes has been effective

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS12597637B2Solid electrolyte and all-solid-state battery

Publication Date: 2026.04.07 TDK CORP

AI summary

A solid electrolyte is composed of a compound represented by the general formula LixM2(PO4)z where M represents at least one element having a valence of one to four, x represents a number that satisfies 0.800≤x≤1.900, and z represents a number that satisfies 2.600≤z≤2.800.