Monocrystalline Sodium-Ion Cathode Coating for Stable High-Voltage Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sodium-ion batteries face challenges with poor cycle performance and low energy density due to factors like anisotropic volume expansion, stress on particle connections, and chemical interactions with the electrolyte, leading to instability and degradation of cathode materials.
Innovation Solution
A mono-crystalline cathode material with a specific chemical composition (Na1+aNi1-x-y-z-cMnxFeyMzNcO2) is developed, featuring a mono-crystal morphology and surface coating or body phase doping to prevent direct contact with the electrolyte, thereby inhibiting crystal phase transitions and enhancing cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If transition metal oxides are used as cathode materials for sodium-ion batteries, then specific capacity is improved, but cycle performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core maintains high-capacity transition metal oxide composition while the shell provides protective coating with different chemical properties. This allows different regions of the material to have optimized properties: the core for high capacity and the shell for stability and protection against electrolyte degradation.
Solution Approach 2:
The patent uses composite materials by combining transition metal oxide with protective coating materials to form a composite cathode structure. This composite approach allows the material to simultaneously achieve high specific capacity from the transition metal oxide core and improved cycle performance from the stable protective shell, resolving the contradiction between capacity and durability.
2Reliability
If surface coating is applied to prevent material-electrolyte contact, then cycle stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the protective coating on the cathode material surface before battery assembly and operation. This pre-coating approach ensures that the material is protected from electrolyte contact from the outset, preventing degradation before it occurs and simplifying the overall manufacturing process compared to post-assembly treatments.
Solution Approach 2:
The patent uses parameter changes by optimizing coating thickness, composition ratios, and thermal treatment parameters to achieve effective protection with minimal processing steps. By carefully controlling these parameters, the patent reduces manufacturing complexity while maintaining high cycle stability, finding an optimal balance between protection and process simplicity.
3Quantity of substance
If high voltage operation is implemented, then energy density is improved, but chemical interaction with electrolyte increases
Solution Approach 1:
The patent applies the intermediary principle by introducing a protective coating layer as a mediator between the cathode material and the electrolyte. This intermediate layer allows high voltage operation to proceed without direct harmful chemical interactions, as the coating acts as a barrier that prevents electrolyte decomposition and material degradation while still permitting ion transport.
Solution Approach 2:
The patent uses preliminary anti-action by applying a protective coating before high voltage operation begins. This pre-established protective layer prevents the harmful chemical interactions that would otherwise occur at high voltages, counteracting the degradation mechanisms before they can affect the cathode material's performance and 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 mono-crystalline cathode material improves the structural stability and cycle performance of sodium-ion batteries, particularly at high temperatures and high voltages, by preventing particle fragmentation and side reactions, thus enhancing the battery's overall stability and longevity.
Implementation Method 1
surface coating or performing body phase doping and surface coating modification at the same time can effectively avoid direct contact between the material and an electrolyte
Data Source
AI summary
The present invention relates to a mono-crystalline cathode material for sodium-ion battery and a preparation method and application thereof. The mono-crystalline cathode material for a sodium ion battery contains the chemical formula of Na1+aNi1-x-y-z-cMnxFeyMzNcO2, wherein −0.40≤a≤0.25, 0.08≤x≤0.5, 0.05≤y≤0.5, 0≤z<0.26, 0<c<0.1, the M and N are both one or a combination of two or more selected from the group consisting of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu elements. The mono-crystalline cathode material for sodium-ion battery has a specific chemical composition, has a mono crystal morphology, and good structural stability and integrity. Particle fragmentation can not be produced in the cyclic process, and meanwhile, the cyclic stability of the sodium-ion battery can be improved.