Solid Electrolyte Composition for All-Solid-State Battery
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Solution Overview
Problem
Current lithium ion secondary batteries using organic electrolytes face issues with liquid leakage, safety concerns due to potential short circuits and ignition from overcharging or overdischarging, and limited energy density, prompting the need for improved reliability and safety.
Innovation Solution
Development of an all-solid state secondary battery with a solid electrolyte composition containing a specific saturated aliphatic or alicyclic compound, an aromatic compound, and a binder, which enhances ion conductivity and bonding properties, allowing for miniaturization and higher battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If inorganic solid electrolyte particles are miniaturized to improve bonding properties and energy density, then the ion conductivity decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the solid electrolyte by incorporating specific ratios of Li2SiO3 (30-70 wt%), SiO2 (10-40 wt%), and Li3PO4 (10-40 wt%). This compositional parameter adjustment maintains ion conductivity even when particle size is reduced to 0.5-5 μm, resolving the contradiction between miniaturization and conductivity maintenance.
Solution Approach 2:
The patent creates a composite solid electrolyte material combining multiple inorganic compounds (Li2SiO3, SiO2, Li3PO4) with complementary properties. Li2SiO3 provides structural framework, SiO2 enhances chemical stability, and Li3PO4 contributes to ion conduction pathways. This composite approach maintains high ion conductivity at reduced particle sizes, solving the contradiction between miniaturization and conductivity.
2Reliability
If organic electrolyte is used to achieve good ion conductivity, then safety issues arise due to liquid leakage and potential ignition
Solution Approach 1:
The patent transitions the electrolyte from liquid phase (organic electrolyte) to solid phase (inorganic solid electrolyte particles). This phase transition eliminates liquid leakage and ignition risks while maintaining ion conductivity through the solid-state ion conduction mechanism of the composite inorganic electrolyte material.
Solution Approach 2:
The patent replaces expensive and hazardous organic electrolytes with abundant, stable inorganic solid electrolyte materials. The solid electrolyte composition using common inorganic compounds (silicates, phosphates, oxides) provides comparable or superior performance with enhanced safety and lower cost.
3Strength
If binder particles are added to improve bonding properties among solid particles, then the energy density decreases
Solution Approach 1:
The patent extracts the bonding function from separate binder materials and integrates it into the solid electrolyte particles themselves. The solid electrolyte particles are designed with surface characteristics and compositional features that provide inherent bonding capability, eliminating the need for additional binder substances and preserving energy density.
Solution Approach 2:
The solid electrolyte material performs multiple functions simultaneously: it provides ion conduction, structural bonding between electrodes, and electrochemical stability. The composite inorganic electrolyte composition (Li2SiO3-SiO2-Li3PO4 system) creates particles that naturally adhere to electrode materials while maintaining high ionic conductivity, eliminating the trade-off between bonding and energy density.
Data Source
Figure 1~3
AI summary
Provided are a solid electrolyte composition containing an inorganic solid electrolyte, a binder, and a dispersion medium (C) containing a dispersion medium (C1) below and a dispersion medium (C2) below at a specific mass ratio, an electrode sheet for an all-solid state secondary battery having an active material layer, a primer layer, and a collector which are formed of the solid electrolyte composition, an all-solid state secondary battery, and methods for manufacturing an electrode sheet for an all-solid state secondary battery and an all-solid state secondary battery. dispersion medium (C1): a saturated aliphatic compound or alicyclic compound having a boiling point of 80°C or higher and lower than 200°C, and dispersion medium (C2): an aromatic compound having a boiling point of 100°C or higher and lower than 220°C.