Negative Current Collector Coating for Uniform Sodium Deposition
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Solution Overview
Problem
Sodium-ion batteries suffer from low energy density and uneven sodium deposition, leading to increased damage risk of the electrolyte interface film and shortened cycle life due to disorderly growth of sodium dendrites on the negative current collector.
Innovation Solution
A negative current collector with a functional layer containing a carbon main material and multifunctional additives like Na2SnO3*3H2O, Na2ZnO2, or NaBiO3, which enhances sodium deposition uniformity and storage capacity, reducing nucleation overpotential and prolonging battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metal sodium is deposited on the negative current collector during the first charge and discharge, then the energy density is improved, but sodium dendrites grow disorderly and the cycle life is shortened
Solution Approach 1:
The patent applies preliminary action by pre-coating the negative current collector with a functional layer containing carbon material and multifunctional additives (Na2SnO3·3H2O, Na2ZnO2, or NaBiO3) before sodium deposition. This functional layer is formed in advance to guide uniform sodium deposition and prevent dendrite formation during subsequent charging cycles, thereby improving cycle life while maintaining high energy density
Solution Approach 2:
The functional layer acts as an intermediary between the negative current collector and deposited sodium. It mediates the deposition process by providing a controlled interface that promotes uniform sodium distribution and prevents direct contact between sodium and the current collector, reducing dendrite growth and electrolyte interface film damage
2Quantity of substance
If metal sodium is used as the negative electrode to improve energy density, then the specific capacity is increased, but sodium deposits unevenly causing electrolyte interface film damage
Solution Approach 1:
The patent applies local quality by incorporating multifunctional additives (Na2SnO3·3H2O, Na2ZnO2, or NaBiO3) at specific concentrations (5-10 mass%) within the functional layer. These additives create localized regions with enhanced sodium deposition guidance capability, ensuring uniform sodium distribution across the current collector surface while maintaining high specific capacity
Solution Approach 2:
The functional layer is constructed as a composite material combining carbon material (60-90 mass%) with multifunctional additives (5-10 mass%). This composite structure leverages the high conductivity of carbon and the sodium-guiding properties of the additives to achieve both high specific capacity and uniform deposition
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 functional layer improves coulombic efficiency and specific capacity by uniformly depositing sodium, reducing dendrite formation, and extending the battery's cycle life.
Implementation Method 1
When sodium batteries without negative active materials are charged and discharged for the first time, metal sodium will be deposited on the negative current collector
Implementation Method 2
M includes an atom capable of forming an alloy with Na
Data Source
AI summary
The present application provides a negative current collector and a preparation method thereof, a sodium secondary battery, and an electrical device. The negative current collector includes a matrix and a functional layer disposed on at least one side of the matrix and includes a multifunctional additive. The multifunctional additive includes NaxMNy*zH2O, where: M includes an atom capable of forming an alloy with Na; N includes at least one of atom O, atom S, or atom Se; and 0<x≤5, 0<y≤5, and 0≤z≤5.