The present invention focuses on designing the composition of layered sodium transition metal (TM) oxides to develop P2-type layered Na-TM oxides with high Na- content, specifically in the range of 0.83 to 0.85 per formula unit (p.f.u.). More specifically, it pertains to high Na-content (approximately 0.84 p.f.u.) P2-type layered sodium transition metal oxides (NaTM-oxides) as high-performance cathode materials for Na-ion batteries. This high Na-containing P2-type layered Na-TM-oxide cathode material is achieved by tuning the composition through the selection of TM and non-TM cations/dopants based on their cationic potentials (which reflect the charge density on the surface of an ion). This maximizes the cationic potential in the TM-layer of the Na-TM-oxide structure while maintaining charge neutrality and ensuring the P2-type structure is preserved.
Figure (1) A scanning electron micrograph (SEM) of the synthesized Na0.84([ ]0.06Li0.04Mg0.02Ni0.22Mn0.66)O2.; (2) Na-ion 8full9 cell with high Na-containing P2-type NaTMO2 based cathode and home- made mushroom derived carbon-based anode shows a 1st cycle specific discharge capacity of 130 mAh/g and energy density of ~390 Wh/kg (based on electrode mass); with good capacity retention.
The sodium ion (Na-ion) battery system is an emerging electrochemical energy storage technology, offering benefits due to the widespread availability and lower cost of sodium. Layered sodium transition metal oxides (Na-TM-oxides) are being investigated as a crucial class of high-capacity cathode materials. However, practical usage is hindered by the lower initial sodium content in P2-type Na-TM-oxides and various instabilities, which lead to a significant decrease in sodium storage capacity during electrochemical cycling and overall inferior performance as a cathode material.
- High Reversible Na-Storage Capacity: Exhibits initial reversible Na-storage capacities of approximately 178 mAh/g at C/5 in the first cycle and 151 mAh/g reversible capacity at C/5.
- Optimized Charge Density: Achieves high charge density by carefully selecting the types and contents of 3d transition metal ions in the transition metal (TM) layer to optimize the cationic potential of the TMO2 slab.
- Enhanced Sodium Content: Enhances the Na-content in the Na-layer while preserving the P2-type layered structure and maintaining overall charge neutrality.
- Structural Stability Across Voltage Range: Avoids undesirable phase and structural transformations, such as Na-vacancy or TM ordering at low voltages and O2–P2 phase transitions at high voltages.
- Smooth Potential Profiles: Provides stable and smooth potential profiles, ensuring excellent structural integrity and cyclic stability during repeated charge/discharge cycles.
A high-sodium-content P2-type layered sodium transition metal oxide (Na- TM-oxide) cathode active material has been developed. The synthesis method involves mixing, heating, grinding, calcining, and other steps. The product demonstrated high initial reversible Na-storage capacities of approximately 178 mAh/g(initial charge discharge) and 151 mAh/g (reversible charge dishcarge) at a current density equivalent to C/5, respectively, within a cell voltage window of 2-4 V vs Na/Na+ . These capacities represent the highest reported to-date in this voltage range.
The invention is at the stage of demonstration and/or validation in lab environment.
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The developed materials have a potential role in sodium-ion batteries (SIBs) a promising alternative to lithium-ion batteries (LIBs). Widespread use of SIBs can accelerate the decarbonization of the energy sector while promoting global equity and sustainability.
The invention has the potential of application in domains such as battery technology, energy storage, electric vehicles, Consumer electronics and other industrial applications.
Geography of IP
Type of IP
202121053254
406595