Mixed Sodium-Lithium Spinel Cathode for Rechargeable Battery
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Solution Overview
Problem
Existing lithium-ion batteries face challenges with high irreversible capacity loss, capacity degradation, and low rate capability due to the release of oxygen during the first cycle, which affects the performance and longevity of rechargeable lithium cells and batteries.
Innovation Solution
The development of lithium transition metal-oxide electrodes with a mixed sodium/lithium composition, specifically NayLixNizMn(1-z-z′)Mz′Od, where x+y>1, 0<z<0.5, and 0≤z′<0.5, incorporating a spinel or spinel-type component, achieved through an ion-exchange method using a precursor with excess lithium salt in an organic solvent, which balances the positive charge of metallic elements and maintains structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-ion batteries use conventional cathode materials, then they can provide basic energy storage, but they suffer from high irreversible capacity loss and capacity degradation due to oxygen release during the first cycle
Solution Approach 1:
The patent changes the compositional parameters of the cathode material by incorporating a spinel component with specific proportions of metal elements (Ni, Co, Mn, Al) and controlling the overall stoichiometry. This compositional parameter change suppresses oxygen release and reduces irreversible capacity loss while maintaining high capacity
Solution Approach 2:
The patent uses a composite cathode material combining layered and spinel structures. The spinel component (LiMn2O4 phase) provides structural stability and suppresses oxygen release, while the layered component provides high capacity. This composite approach resolves the contradiction between capacity retention and irreversible loss
2Quantity of substance
If lithium-ion batteries use high-capacity cathode materials, then they can provide higher energy density, but they exhibit low rate capability
Solution Approach 1:
The patent segments the cathode material into two functional components: a layered component (providing high capacity) and a spinel component (providing high rate capability). This segmentation allows each component to perform its specialized function, resolving the contradiction between capacity and rate capability
Solution Approach 2:
The patent applies local quality by giving different regions of the composite material different properties. The spinel-rich regions provide fast ion transport pathways for high rate capability, while the layered regions provide high capacity. This local differentiation resolves the capacity-rate contradiction
3Adaptability or versatility
If lithium-ion batteries use blended cathode materials (NCA + spinel), then they can achieve bi-functional behavior with high-rate and high-energy capabilities, but the structure becomes more complex
Solution Approach 1:
The patent merges the high-rate capability of spinel materials with the high-energy density of layered NCA materials into a single composite cathode structure. This merging achieves bi-functional behavior while simplifying the overall battery design compared to using separate electrodes for different functions
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
This approach results in electrodes with low irreversible capacity loss (<10% on the first cycle), high capacity (220 mAh/g), and high-rate capability (150 mAh/g), maintaining structural integrity and performance over multiple cycles without the need for specialized coatings.
Implementation Method 1
The ion-exchange method consists of treating a precursor material with excess lithium salt in an organic solvent
Data Source
AI summary
A positive electrode is disclosed for a non-aqueous electrolyte lithium rechargeable cell or battery. The electrode comprises a lithium containing material of the formula NayLixNizMn1-z-z′Mz′Od, wherein M is a metal cation, x+y>1, 0<z<0.5, 0≤z′<0.5, y+x+1 is less than d, and the value of d depends on the proportions and average oxidation states of the metallic elements, Li, Na, Mn, Ni, and M, if present, such that the combined positive charge of the metallic elements is balanced by the number of oxygen anions, d. The inventive material preferably has a spinel or spinel-like component in its structure. The value of y preferably is less than about 0.2, and M comprises one or more metal cations selected preferably from one or more monovalent, divalent, trivalent or tetravalent cations, such as Mg2+, Co2+, Co3+, B3+, Ga3+, Fe2+, Fe3+, Al3+, and Ti4+. The electrode material can be synthesized using an ion-exchange reaction with a lithium salt in an organic-based solvent to partially replace sodium ions of a precursor material with lithium ions.