Electrolyte Additives for Lithium Metal Battery Cycle Life
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Solution Overview
Problem
Rechargeable batteries with metallic lithium electrodes exhibit limited cycle lifetimes due to the limitations in cathode active material reduction and oxidation electrochemical processes, particularly in lithium-containing batteries, necessitating improvements in cycle lifetime and performance.
Innovation Solution
Incorporating specific additives with structures defined by Formulas (I) and (II) into electrochemical cells, which can be present in the electrolyte or as precursors, to enhance the electrochemical performance by modifying the lithium ion intercalation and compound formation processes, thereby improving the battery's cycle life and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic lithium electrodes are used in rechargeable batteries, then energy density is improved, but cycle lifetime deteriorates
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance in the electrolyte that mediates between the metallic lithium electrode and the cathode active material. This additive forms a protective interface layer that facilitates lithium ion transport while preventing harmful direct interactions, thereby extending cycle lifetime without sacrificing the high energy density benefits of metallic lithium electrodes
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (Formula I where Q=F). This parameter change in electrolyte composition alters the electrochemical behavior at the electrode interfaces, enabling stable cycling of metallic lithium electrodes while maintaining high energy density
2Quantity of substance
If cathode active materials undergo reduction and oxidation processes, then electrochemical capacity is improved, but material stability deteriorates
Solution Approach 1:
The fluorinated cyclic carbonate additive performs preliminary action by forming a stable protective interface layer on the cathode active material surface before extensive reduction and oxidation cycles occur. This pre-formed protective layer prevents direct degradation of the cathode material during electrochemical cycling, maintaining material stability while allowing high electrochemical capacity utilization
Solution Approach 2:
The additive acts as an intermediary between the cathode active material and the electrolyte, creating a protective interface that mediates the reduction and oxidation processes. This intermediary layer allows electrochemical reactions to proceed with high capacity while protecting the cathode material from structural degradation and maintaining long-term stability
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 use of these additives increases the cycle lifetimes of lithium-based batteries, reduces lithium depletion, and improves lithium morphologies, leading to more compact and efficient energy storage.
Implementation Method 1
cathode active materials may electrochemically intercalate lithium ions and/or produce soluble and insoluble lithium compounds during the charge-discharge process
Implementation Method 2
lithium ions...electrochemically intercalate...during the charge-discharge process
Data Source
AI summary
Articles and methods including additives in electrochemical cells, are generally provided. As described herein, such electrochemical cells may comprise an anode, a cathode, an electrolyte, and optionally a separator. In some embodiments, at least one of the anode, the cathode, the electrolyte, and/or the optional separator may comprise an additive and/or additive precursor. For instance, in some cases, the electrochemical cell comprises an electrolyte and an additive and/or additive precursor that is soluble with and/or is present in the electrolyte. In some embodiments, the additive precursor comprises a disulfide bond. In certain embodiments, the additive is a carbon disulfide salt. In some cases, the electrolyte may comprise a nitrate.