Copolymer-Coated Positive Electrode for Stable Solid-State Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium batteries with solid electrolytes face challenges in maintaining high energy density and stability due to interfacial side reactions between the sulfide-based solid electrolyte and positive active material, leading to capacity reduction and cycle deterioration, especially at high voltages and during charge/discharge cycles.
Innovation Solution
A composite positive electrode with a coating layer containing a copolymer having a polymeric ionic liquid (PIL) is used, which includes a first repeating unit providing charge stability and a second repeating unit for mechanical properties, minimizing interfacial reactions and preventing deformation from volume changes, thereby enhancing lithium ion conductivity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfide-based solid electrolyte is used to achieve high ionic conductivity and fast charging/discharging, then ionic conductivity is improved, but interfacial side reactions with the positive active material increase, leading to capacity reduction and cycle deterioration
Solution Approach 1:
A coating layer comprising a copolymer of formula (1) and formula (2) is introduced as an intermediary between the sulfide-based solid electrolyte and the positive active material. This coating layer acts as a protective barrier that prevents direct contact and harmful interfacial reactions while maintaining efficient lithium ion transport, thus resolving the contradiction between achieving high ionic conductivity and preventing interfacial side reactions
2Quantity of substance
If the positive electrode operates at high voltage to increase energy density, then energy density is improved, but stability at high temperature decreases and interfacial side reactions worsen
Solution Approach 1:
The copolymer coating layer serves as a stable intermediary interface that enables the electrode to operate at high voltages (4.3V or higher) without suffering from high temperature degradation. The coating layer maintains its structural integrity and protective function under high voltage and temperature conditions, allowing high energy density operation while preserving stability
Solution Approach 2:
The positive electrode is designed as a composite structure with the positive active material (such as LiCoO2, LiNi0.8Co0.1Mn0.1O2, or LiNi0.9Co0.05Mn0.05O2) coated with the copolymer layer. This composite structure combines the high voltage capability of the positive active material with the protective and stabilizing properties of the copolymer coating, enabling both high energy density and high temperature stability
3Stability of the object's composition
If a coating layer is added to reduce interfacial side reactions, then stability is improved, but device complexity increases
Solution Approach 1:
The solution involves creating a composite material by coating the positive active material particles with the copolymer layer. This approach enhances interface stability through the composite structure while avoiding the complexity of multi-layer coatings or complex device architectures. The copolymer coating can be applied directly to the particle surfaces, forming a simple yet effective protective layer that improves stability without significantly complicating the electrode structure
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 positive electrode achieves improved stability, mechanical properties, and reduced side reactions, resulting in enhanced cycle characteristics and high energy density for lithium batteries, even under high voltage and repeated charge/discharge conditions.
Implementation Method 1
A composite positive electrode with a coating layer containing a copolymer having a polymeric ionic liquid (PIL) is used, which includes a first repeating unit providing charge stability and a second repeating unit for mechanical properties
Implementation Method 2
enhancing lithium ion conductivity and cycle characteristics
Data Source
AI summary
A positive electrode includes a composite material including a positive active material and a coating layer on a surface of the positive active material, wherein the coating layer includes a copolymer including a first repeating unit represented by Formula 1 below and a second repeating unit represented by Formula 2 below:wherein Ar1, R1 to R6, A, A1,Y−, m, and n are the same as defined in the specification.