Sodium Metal Battery Anode Layer for Uniform Sodium Deposition
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Solution Overview
Problem
Sodium metal batteries face issues with uneven sodium deposition on the negative electrode current collector due to inhomogeneous surface distribution and high reactivity with the electrolyte, leading to dendrite formation and degradation of battery performance.
Innovation Solution
A sodium metal battery design that forms a uniform sodium deposition layer on the negative electrode current collector with a thickness of ≥30 nm after the first charge-discharge cycle, utilizing the first irreversible capacity of the positive electrode material and optimizing the battery cell design to reduce deposition overpotential and ensure uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-negative electrode sodium metal battery is used with in situ deposition, then energy density is improved, but sodium deposition uniformity deteriorates
Solution Approach 1:
A sodium-containing layer is pre-formed on the negative electrode current collector before battery operation. This preliminary sodium layer serves as nucleation sites that guide subsequent sodium deposition, ensuring uniform distribution during charge-discharge cycles and preventing dendrite formation while maintaining high energy density
Solution Approach 2:
The negative electrode current collector is provided with a localized sodium-containing layer rather than uniform sodium coating throughout. This localized treatment creates specific nucleation zones that control sodium deposition patterns, improving uniformity where needed while maintaining the in situ deposition mechanism for high energy density
2Use of energy by moving object
If sodium metal is deposited on negative electrode current collector, then energy density is improved, but side reaction with electrolyte increases
Solution Approach 1:
The state of sodium on the negative electrode is changed from bulk metal to a controlled thin layer with specific thickness and composition. By adjusting the sodium content and distribution parameters in the pre-formed layer, the reactivity with electrolyte is reduced while maintaining sufficient sodium for high energy density operation
Solution Approach 2:
The sodium-containing layer acts as an intermediary between the highly reactive sodium metal and the electrolyte. This intermediate layer moderates the interaction, reducing direct contact and side reactions between sodium and electrolyte while still enabling the necessary electrochemical reactions for energy storage
3Use of energy by moving object
If sodium metal is deposited on negative electrode current collector, then energy density is improved, but dendrite formation increases
Solution Approach 1:
A sodium-containing layer is pre-formed on the negative electrode current collector before battery operation. This preliminary sodium layer serves as nucleation sites that guide subsequent sodium deposition, ensuring uniform distribution during charge-discharge cycles and preventing dendrite formation while maintaining high energy density
Solution Approach 2:
The sodium distribution in the negative electrode is made more homogeneous through the pre-formed sodium-containing layer. This uniform distribution prevents localized concentration gradients that lead to dendrite growth, ensuring reliable and safe battery operation at high energy density
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 ensures uniform sodium deposition and reversibility of the charge-discharge process, reducing the risk of dendrite formation and enhancing the cycling performance and safety of the battery.
Implementation Method 1
a 'non-negative electrode' sodium metal battery has been developed by in situ deposition of sodium deintercalated from the positive electrode material to the negative electrode current collector
Implementation Method 2
the sodium layer deposited in situ on the negative electrode current collector having a thickness of ≥30 nm after the battery is charged and discharged for the first time
Implementation Method 3
the area with active sodium residue is more likely to deposit sodium metal in the subsequent charge process due to its lower nucleation energy
Data Source
AI summary
A sodium metal battery and an electrochemical apparatus, the battery has a positive electrode sheet and a negative electrode sheet, the negative electrode sheet being a negative electrode current collector, and a sodium layer deposited in situ on the negative electrode current collector having a thickness of ≥30 nm after the battery is charged and discharged for the first time. After the battery cell is charged and discharged for the first time, the amount of residual sodium metal is sufficient to uniformly form a sodium deposition layer with a certain thickness on the surface of the negative electrode current collector. The higher nucleation energy required for the deposition of sodium onto the surface of the current collector during subsequent charge-discharge cycles is avoided, the overall deposition overpotential is reduced, and the deposition uniformity of sodium metal and the reversibility of the charge-discharge process are ensured.