Polymer-Coated Lithium Metal Electrode for Dendrite-Controlled Recharging
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Solution Overview
Problem
Lithium ion batteries face safety hazards due to flammable organic electrolytes and dendrite formation, while lithium metal batteries suffer from poor cycle life and dendrite-induced shorts, and both types rely on scarce and costly lithium resources.
Innovation Solution
A rechargeable lithium metal battery design using a conformable polymer-coated negative electrode and a low-temperature inorganic molten salt electrolyte, with a block or graft copolymer providing ion selectivity to prevent dendrite formation and enhance safety, combined with a method to modulate electrical potential to control electrodeposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If flammable organic electrolytes are used in lithium ion batteries, then high energy density is achieved, but safety hazards increase due to fire and explosion risks
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte by using inorganic molten salts (such as eutectic mixtures of LiCl-KCl-CaCl2) instead of organic electrolytes. This substitution fundamentally alters the safety profile while maintaining ionic conductivity, resolving the contradiction between energy density and safety hazards.
Solution Approach 2:
The patent introduces a conformable polymer coating as an intermediary layer on the negative electrode. This polymer layer acts as a mediator that prevents direct contact between the lithium metal and the electrolyte, reducing dendrite formation and improving safety while allowing ion transport, thus resolving the safety hazards without sacrificing energy density.
2Quantity of substance
If lithium metal is used in the negative electrode, then capacity is increased, but dendrite formation occurs leading to shorts and poor cycle life
Solution Approach 1:
The patent applies a conformable polymer thin film coating on the lithium metal negative electrode. This flexible polymer layer conforms to the electrode surface and accommodates volume changes during cycling while preventing dendrite penetration, thus maintaining high capacity while improving cycle life and reliability.
Solution Approach 2:
The conformable polymer coating serves as a preventive cushioning layer applied beforehand to the lithium metal electrode. It cushions against dendrite formation and mechanical stress during cycling, preventing shorts and extending cycle life while preserving the high capacity benefits of lithium metal.
3Loss of time
If lithium metal batteries are manufactured in the fully charged state, then manufacturing time is reduced, but safety risks increase due to dendrite formation
Solution Approach 1:
The conformable polymer coating is applied to the lithium metal negative electrode before battery assembly and charging. This pre-applied protective film prevents dendrite formation from the outset, enabling safe manufacture in the fully charged state without the usual safety risks associated with dendrites.
Solution Approach 2:
The patent performs the protective coating action in advance by applying the conformable polymer layer to the lithium metal electrode before charging. This preliminary protective measure eliminates the need for cautious charging protocols and enables safe, rapid manufacturing in the fully charged state.
4Object-affected harmful factors
If inorganic molten salt electrolyte is used, then safety is improved by eliminating flammability, but operating temperature requirements increase
Solution Approach 1:
The patent changes the composition parameters of the electrolyte by using eutectic mixtures of inorganic salts (LiCl-KCl-CaCl2) that have lower melting points than individual components. This composition optimization allows the electrolyte to remain liquid at lower temperatures, reducing the operating temperature requirement while maintaining non-flammability.
Solution Approach 2:
The patent uses a composite electrolyte system combining inorganic molten salt with a conformable polymer matrix. This composite material integrates the non-flammable properties of inorganic salts with the low-temperature flexibility of polymers, achieving both safety improvement and reduced operating temperature requirements.
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 design achieves improved cycle life, safety, and reduced dendrite formation, enabling high energy density and cost-effective operation using abundant materials, while allowing rechargeability and reducing the risk of fires and explosions.
Implementation Method 1
the solid electrolyte comprises a conformable polymer that preferentially conducts ions of the first metal compared to ions of the second metal
Implementation Method 2
electrodepositing, while monitoring electrochemical noise of the electrochemical cell, lithium ions as lithium metal onto the negative electrode by applying an electrical potential or current
Implementation Method 3
a low-temperature inorganic molten salt electrolyte
Implementation Method 4
The lithium ions migrate through the electrolyte to the positive electrode
Implementation Method 5
As the LMB recharges, lithium ions are reduced back to lithium metal as electrons flow back into the negative electrode
Data Source
AI summary
Provided are a conformable polymer coated lithium metal electrode, a solid electrolyte, and an inorganic molten salt electrolyte for a rechargeable lithium metal battery. Systems and methods are also provided for controlling the electroplating of lithium metal onto negative electrodes to allow for more rapid recharging of lithium metal batteries while minimizing dendrite formation.