Composite Negative Electrode for Uniform Lithium Deposition
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Solution Overview
Problem
Conventional lithium ion batteries face issues with low gravimetric energy density, high energy storage costs, and safety risks due to dendrite growth and electrode swelling, which can lead to thermal runaway and explosion.
Innovation Solution
A negative electrode structure comprising an active layer and a composite layer with lithiophilic nanoparticles, metal nanoparticles, and a binder, where the binding energy of the lithiophilic nanoparticles with lithium is less than or equal to −2.5 eV, and the metal nanoparticles have a standard Gibbs free energy of reaction less than 0, ensuring a weight ratio of 1:1 to 8:1, and a binder content of 10 wt% to 25 wt%, facilitating uniform lithium deposition and inhibiting dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If energy density is increased to reduce cost and improve performance, then energy capacity is improved, but safety problems occur such as dendrite growth, battery swelling, heating, and thermal runaway
Solution Approach 1:
A composite layer comprising lithiophilic nanoparticles, metal nanoparticles, and a binder is introduced as an intermediary between the negative electrode and lithium ions. This composite layer mediates lithium deposition by providing nucleation sites that promote uniform lithium distribution, thereby preventing dendrite growth while maintaining high energy capacity
Solution Approach 2:
The binding energy of the lithiophilic nanoparticle with lithium is specifically controlled to be less than or equal to −2.5 eV, and the weight ratio of lithiophilic nanoparticle to metal nanoparticle is optimized to 1:1 to 8:1. These parameter optimizations ensure strong lithium affinity for uniform deposition while preventing excessive reactivity that could cause safety issues
2Quantity of substance
If metal is deposited in dendritic form during charging, then energy storage capacity is improved, but the dendrites may penetrate the separator and cause short-circuiting and explosion
Solution Approach 1:
The composite layer acts as an intermediary that intercepts lithium ions before they reach the negative electrode, providing controlled nucleation sites that promote uniform lithium distribution and prevent dendritic growth patterns
Solution Approach 2:
The composite layer is pre-formed on the negative electrode before charging begins, creating a protective interface that guides lithium deposition from the outset and prevents dendrite formation before they can penetrate the separator
3Ease of operation
If conventional liquid electrolyte is used, then battery operation is simple, but gravimetric energy density is low and life cycle is limited
Solution Approach 1:
The binding energy parameter of the lithiophilic nanoparticle is optimized to be less than or equal to −2.5 eV, creating strong lithium affinity that enhances lithium ion acceptance and storage capacity, thereby improving gravimetric energy density while maintaining operational simplicity
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 solution enhances lithium ion battery performance by achieving high energy density, improving safety, and extending the battery's lifespan by mitigating dendrite growth and electrode swelling.
Implementation Method 1
the binding energy (ΔE) of the lithiophilic nanoparticle with lithium is less than or equal to −2.5 eV
Implementation Method 2
the metal nanoparticle has a standard Gibbs free energy of reaction (ΔrG) less than 0
Data Source
AI summary
A negative electrode and a lithium ion battery employing the same are provided. The negative electrode includes an active layer and a composite layer disposed on the active layer. The composite layer includes a lithiophilic nanoparticle, a metal nanoparticle and a binder. The binding energy (ΔE) of the lithiophilic nanoparticle with lithium is less than or equal to −2.5 eV. The metal nanoparticle has a standard Gibbs free energy of reaction (ΔrG) less than 0. The weight ratio of the lithiophilic nanoparticle to the metal nanoparticle is from 1:1 to 8:1, and the amount of binder is from 10 wt % to 25 wt %, based on the total weight of the lithiophilic nanoparticle and the metal nanoparticle.