Aqueous Polymer Electrolyte for Wider-Window Lithium Batteries
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Solution Overview
Problem
Aqueous lithium rechargeable batteries face limitations due to a narrow potential window and low cycle stability, restricting the use of high-capacity lithium metal and silicon negative electrodes and resulting in lower energy density compared to commercial lithium rechargeable batteries.
Innovation Solution
An aqueous polymer electrolyte comprising a polymer of a single lithium salt, such as poly LiSTFSI, combined with short-chain dimethylsiloxane or fluoro ether, and water, which forms a film with a controlled water content and flexible structure, enhancing ionic conductivity and mechanical strength while expanding the potential window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aqueous electrolyte is used, then safety issues are fundamentally solved and production costs are reduced, but the operating voltage and energy density are much lower than commercial lithium rechargeable batteries
Solution Approach 1:
The patent changes the concentration parameter of the electrolyte by using high salt concentration (21 M) to expand the potential window from 1.23 V to 2.3 V, thereby improving energy density while maintaining safety benefits of aqueous electrolytes
Solution Approach 2:
The patent uses composite electrolyte systems combining high salt concentration aqueous electrolytes with specific electrode materials (lithium metal, silicon, lithium alloys) to achieve both safety and high energy density
2Power
If high salt concentration electrolytic solutions are used, then the oxidation potential is significantly increased enabling higher specific capacity positive electrode materials, but the reduction potential is not much widened and energy density remains much lower than commercial batteries
Solution Approach 1:
The patent simultaneously optimizes multiple parameters including salt concentration (21 M), electrode material selection (lithium metal, silicon, lithium alloys with very high specific capacity), and electrode/aqueous electrolyte interface control to achieve both high oxidation and reduction potentials
Solution Approach 2:
The patent creates controlled interfaces between electrodes and aqueous electrolyte that locally modify water activity and widen the potential window at the electrode surface, enabling high capacity electrodes to function effectively
3Ease of operation
If the electrode surface is coated with a hydrophobic colloidal electrolyte, then low operating voltage negative electrodes can cycle in high salt concentration aqueous electrolytic solution, but the battery system only maintains short-term cycle stability (up to 50 cycles) and requires extremely complicated battery assembly
Solution Approach 1:
The patent removes the hydrophobic colloidal electrolyte coating and replaces it with a simplified direct contact aqueous electrolyte system, eliminating the need for complex coatings while achieving long-term cycle stability through optimized electrode and electrolyte composition
Solution Approach 2:
The patent replaces complex, unstable hydrophobic colloidal coatings with a simple, stable aqueous electrolyte system that requires no additional coating layers or complex assembly procedures
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 aqueous polymer electrolyte achieves a wider potential window, improved cycle stability, and high ionic conductivity, enabling the use of high-capacity lithium metal and silicon electrodes, thus enhancing the energy density and practicality of aqueous lithium rechargeable batteries.
Implementation Method 1
The polymer electrolyte and water form an aqueous polymer electrolyte that confines water molecules through the polymer matrix structure
Implementation Method 2
an ionic conductivity of more than 10−4 Scm−1 at room temperature
Data Source
AI summary
The present disclosure provides an aqueous polymer electrolyte comprising a polymer electrolyte of a polymer of a single lithium salt, or a polymer of a single lithium salt and short-chain dimethylsiloxane or single fluoro ether, and water. The present disclosure further provides a lithium rechargeable battery comprising such an aqueous polymer electrolyte.