Composite Electrode Layer for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
All-solid-state secondary batteries face challenges with high ion conduction resistance and interface resistance due to electrode expansion/contraction, leading to degraded cycle life and discharge rate performance, especially at low temperatures.
Innovation Solution
Incorporating polymer fibers with an average diameter of 1 nm to 100 nm and inorganic solid particles like Al2O3, TiO2, or phosphate compounds with a NASICON structure into the positive electrode active material-containing layer, which reduces ion conduction resistance and maintains high-speed lithium ion conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid electrolytes, nonvolatile electrolytic solutions, or incombustible electrolytic solutions are used to improve safety performance, then safety is improved, but discharge rate performance, low-temperature performance, and long-life performance deteriorate
Solution Approach 1:
The patent uses a composite electrolyte system combining solid electrolyte particles (oxide or sulfide with 10^-4 to 10^-2 S/cm conductivity) dispersed in a nonaqueous electrolytic solution. This composite structure provides both safety benefits of solid electrolytes and the high ionic conductivity of liquid electrolytes, resolving the contradiction between safety and discharge rate performance.
Solution Approach 2:
The patent changes the physical state parameters of the electrolyte by using a hybrid solid-liquid system. The solid electrolyte particles (0.1 to 10 μm) suspended in the liquid electrolyte create intermediate states that provide both the safety of solids and the performance of liquids, allowing simultaneous improvement of safety and discharge rate characteristics.
2Reliability
If oxide solid electrolyte or sulfide solid electrolyte is used to improve ionic conductivity, then ionic conductivity is improved, but ion conduction resistance and reaction resistance in electrodes remain high, degrading discharge performance and low-temperature performance
Solution Approach 1:
The patent creates a composite electrolyte system where solid electrolyte particles (oxide or sulfide) are dispersed in a nonaqueous electrolytic solution. The solid particles provide high ionic conductivity pathways while the liquid matrix ensures good wetting and reduces interfacial resistance, resolving the contradiction between ionic conductivity and discharge performance.
Solution Approach 2:
The nonaqueous electrolytic solution acts as an intermediary medium that facilitates ion transport between the solid electrolyte particles and the electrodes. This liquid matrix reduces the high interfacial resistance that would otherwise exist between solid electrolyte and electrode surfaces, enabling both high ionic conductivity and good discharge performance.
3Duration of action of moving object
If charge-and-discharge cycles are performed, then battery operation is achieved, but expansion/contraction of electrodes causes disconnection of ion conduction paths, increasing resistance and degrading interface resistance and cycle life performance
Solution Approach 1:
The patent uses a liquid-containing electrolyte system that can dynamically adapt its volume and flow characteristics during electrode expansion and contraction. The liquid electrolyte maintains continuous ionic conduction paths despite mechanical changes in electrode volume, preventing disconnection and maintaining low interface resistance throughout charge-discharge cycles.
Solution Approach 2:
The nonaqueous electrolytic solution serves as a flexible intermediary that accommodates electrode volume changes during cycling. Unlike rigid solid electrolytes, the liquid electrolyte can flow and redistribute to maintain continuous ionic pathways even when electrodes expand or contract, thereby preventing interface resistance degradation and maintaining cycle life performance.
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 solution enhances charge-and-discharge cycle life, discharge rate performance, and low-temperature performance by suppressing ion conduction disconnection and maintaining high lithium ion conductivity, even under significant electrode expansion/contraction.
Implementation Method 1
Incorporating polymer fibers with an average diameter of 1 nm to 100 nm and inorganic solid particles like Al2O3, TiO2, or phosphate compounds with a NASICON structure into the positive electrode active material-containing layer, which reduces ion conduction resistance and maintains high-speed lithium ion conduction
Implementation Method 2
phosphate compounds with a NASICON structure... maintains high-speed lithium ion conduction
Implementation Method 3
degradation caused by expansion and contraction of an electrode
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to one embodiment, there is provided an electrode including active material particles, polymer fibers and inorganic solid particles. The polymer fibers have an average fiber diameter of 1 nm to 100 nm.