Composite Electrolyte for Solid-State Battery Interface Resistance
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Solution Overview
Problem
All solid-state lithium ion secondary batteries face challenges in achieving high capacity due to high interface resistance between the solid electrolyte and active material, which is exacerbated by the swelling and contraction of active materials during lithium insertion and extraction, leading to poor cycle performance.
Innovation Solution
A composite electrolyte is developed comprising inorganic compound particles with lithium ion conductivity, an organic electrolyte, and a binder, where the inorganic compound particles have an average diameter of 0.1 µm to 5 µm and a solvent ratio of 0.1% to 8% by weight, enhancing lithium ion conductivity and reducing electrode resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used in all solid-state lithium ion secondary batteries, then safety is improved (no ignition risk), but interface resistance between the solid electrolyte and active material increases, reducing battery capacity
Solution Approach 1:
The patent uses a composite electrolyte consisting of inorganic compound particles (such as lithium-containing oxide) dispersed in an organic electrolyte medium. This composite structure combines the safety advantages of solid electrolytes with the low resistance characteristics of liquid electrolytes, achieving both high safety and low interface resistance
Solution Approach 2:
The patent optimizes the particle size of inorganic compound particles to 0.1 µm to 5 µm and controls the solvent ratio in the organic electrolyte to 0.1% to 8% by weight. These parameter optimizations reduce interface resistance while maintaining the safety benefits of the solid-like electrolyte structure
2Strength
If heat is applied to bond the solid electrolyte and active material, then initial interface bonding is improved, but the active material peels off during repeated charging and discharging due to swelling and contraction
Solution Approach 1:
The organic electrolyte component provides a flexible, adaptable interface that can accommodate the swelling and contraction of active material during charge-discharge cycles. This flexible matrix prevents peeling while maintaining good contact, solving the cycle performance problem
Solution Approach 2:
The composite electrolyte structure combines the bonding capability of solid inorganic particles with the flexibility and adaptability of liquid organic electrolyte, creating an interface that maintains strong adhesion through multiple cycles despite active material volume changes
3Productivity
If the average particle diameter of inorganic compound particles is reduced to enhance lithium ion conductivity, then rate performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent specifies an optimal particle size range of 0.1 µm to 5 µm for inorganic compound particles. This parameter optimization achieves high lithium ion conductivity and excellent rate performance while remaining feasible for industrial manufacturing, avoiding the complexities of ultra-fine particle processing
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 composite electrolyte improves rate performance and low temperature performance by promoting lithium ion movement and reducing gelation time, thereby enhancing the cycle life and stability of the battery.
Implementation Method 1
inorganic compound particles having lithium ion conductivity at 25°C of 1×10-10[0010]The composite electrolyte includes inorganic compound particles having lithium ion conductivity
Implementation Method 2
an organic electrolyte, and a binder... enhancing lithium ion conductivity... promoting lithium ion movement and reducing gelation time
Data Source
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AI summary
According to one approach, a composite electrolyte is provided. The composite electrolyte includes inorganic compound particles having lithium ion conductivity at 25°C of 1 × 10-10 S/cm or more and including a solvent, an organic electrolyte, and a binder. An average particle diameter of the inorganic compound particles is 0.1 µm or more and less than 5 µm, and a ratio of a weight of the solvent to a total weight of the inorganic compound particles and the solvent is 0.1% by weight or more and less than 8% by weight.