Polymer Solid Electrolyte Additives for Stable Lithium Battery Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges in achieving both high ion conductivity and interfacial stability, particularly due to the instability of polymer electrolytes when used in lithium secondary batteries, which affects the performance and longevity of the batteries.
Innovation Solution
A polymer solid electrolyte is developed comprising a polymer, a lithium salt, and an organic compound with a high highest occupied molecular orbital (HOMO) energy level as an additive, which enhances ion conductivity and oxidation stability, facilitating better film formation and adsorption on the positive electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer electrolyte is used to improve environmental friendliness and processability, then ion conductivity is improved, but interfacial stability deteriorates
Solution Approach 1:
The patent introduces a protective film formed by organic compounds (such as vinylene carbonate, fluoroethylene carbonate, or their derivatives) as an intermediary layer between the polymer electrolyte and the positive electrode. This intermediary film mediates the interaction at the interface, preventing direct contact between the unstable polymer electrolyte and the electrode, thereby improving interfacial stability while maintaining high ion conductivity through the protective film.
2Reliability
If high HOMO energy organic compound is added to enhance ion conductivity, then charge transfer is facilitated, but oxidation stability deteriorates
Solution Approach 1:
The organic compound with high HOMO energy acts as a mediator that facilitates charge transfer between the polymer electrolyte and the positive electrode during charging, while simultaneously forming a protective film that prevents oxidation of the polymer electrolyte at the interface. This dual function resolves the contradiction by enabling beneficial charge transfer while blocking harmful oxidation reactions.
Solution Approach 2:
The patent carefully selects organic compounds with specific HOMO energy parameters (typically -6.0 to -8.0 eV) to optimize the balance between charge transfer facilitation and oxidation resistance. By controlling this key parameter, the protective film achieves the right level of electronic insulation to prevent oxidation while maintaining sufficient ionic conductivity for charge transfer.
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 polymer solid electrolyte improves the performance of lithium secondary batteries by securing high ion conductivity and interfacial stability, thereby enhancing the battery's charging efficiency and overall performance while preventing issues like film degradation and thermal instability.
Implementation Method 1
ion conductivity of a polymer electrolyte may be enhanced up to 10-3 S/cm, that is similar to ion conductivity of a non-aqueous liquid electrolyte by developing an ion conducting polymer electrolyte having high ion conductivity at room temperature and thereby facilitating charge transfer between the polymer and dopants
Implementation Method 2
oxidation is facilitated on a positive electrode surface, which is advantageous in forming a film for protecting a positive electrode, or oxidation stability at a positive electrode interface may be enhanced by adsorbing on the positive electrode surface and protecting the positive electrode surface
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A polymer solid electrolyte having high ion conductivity and interfacial stability. By the polymer solid electrolyte comprising an additive having excellent reachability to a positive electrode surface, and properties of facilitating film formation in a positive electrode due to low oxidation potential, a film is readily formed on the positive electrode surface, and as a result, a lithium secondary battery having enhanced performance may be provided.