Carbon-coated NaTi2 Research Articles

A Liquid-Phase reaction strategy to construct aqueous Sodium-Ion batteries anode with enhanced redox reversibility and cycling stability

NASICON-type NaTi2(PO4)3 compound is strongly considered to be a promising anode material for aqueous sodium-ion batteries, but suffering from low redox reversibility and poor cycling stability due to severe side reactions in aqueous electrolytes. Herein, a novel liquid-phase reaction strategy is reported for in-situ constructing carbon-coated NaTi2(PO4)3 nanocrystals (C-NTP) with enhanced redox reversibility and cycling stability. The construction mechanism, structural properties and electrochemical performance of the C-NTP material are carefully investigated. It is suggested that the material possesses a mesoporous carbon-coating structure and delivers outstanding performance with a high reversible capacity of 114.5 mAh·g−1 at 100 mA·g−1 and an impressive capacity retention of 82.1% after 1000 cycles at 1000 mA·g−1. The enhanced redox reversibility and cycling stability are attributed to the unique carbon-coating structure that improves the reaction kinetics and structural stability of the material owing to the high electronic conductivity and corrosion-resistant ability.

N-modified carbon-coated NaTi2(PO4)3 as an anode with high capacity and long lifetime for sodium-ion batteries.

NASICON-type NaTi2(PO4)3 is recognized as a promising energy storage anode due to its high ionic conductivity and low cost. In this work, N-modified carbon-coated sodium titanium phosphate (NTPGN) composites were prepared by the sol-gel method by using sodium glutamate as a source of nitrogen and partial carbons. The addition of sodium glutamate forms a loose structure of nano-spherical flowers on the surface of sodium titanium phosphate, which shows a higher specific capacity, better rate performance, and excellent cycling performance compared to the carbon-coated titanium phosphate derived only from citric acid. The discharge capacities of NTPGN at 0.1 C, 5 C, 10 C, 20 C, and 30 C are 132.8, 132, 131.4, 105.9, and 98.2 mA h g-1, respectively. In particular, after 1000 cycles at 20 C, the discharge capacity is 102.6 mA h g-1 with a capacity retention rate of 96%. This work reveals that the combination of carbon coating and nitrogen doping using sodium glutamate improves the electrochemical performance of electrode materials.

Regulating Uniform Zn Deposition via Hybrid Artificial Layer for Stable Aqueous Zn-Ion Batteries

Aqueous Zn-ion batteries (ZIBs) have great potential as promising candidates for next-generation energy conversion and storage devices, benefiting from competitive theoretical capacity, low cost, and high security. However, further applications of ZIBs are impeded by dendrite generation and side reactions. Herein, considering that Zn dendrites are caused by nonuniform metal deposition, involving uneven electric field and Zn 2+ ion flux, a dual-functional carbon-coated NaTi 2 (PO 4 ) 3 (NTP-C) artificial protective layer with large surface area is constructed onto the surface of metallic Zn to stabilize Zn anode and regulate uniform Zn deposition. Benefiting from a synergistic strategy, NTP-C coating not only takes advantages of carbon to provide abundant Zn deposition sites to homogenize nucleation, adjust electric field distribution, and reduce local current density but also utilizes the ionic channel in NTP structure to modulate the distribution of Zn 2+ flux at the same time. Consequently, the NTP-C@Zn symmetrical cell exhibits a stable cycling for more than 600 h with a low polarization (18.6 mV) at 1 mA cm −2 /1 mAh cm −2 . Especially, the NTP-C@Zn symmetrical cell even enables a steady plating/stripping process at a harsh condition (100 mA cm −2 ) without short circuit, indicating a potential application of high-load electrodes or supercapacitors. Furthermore, the NTP-C@Zn// α -MnO 2 full cell also displays enhanced electrochemical performance for 1200 cycles with a capacity retention of 76.6% under 5 C (~1.5 A g −1 ). This work provides a synergistic strategy combining two protective mechanisms and delivers new inspirations for the improvement of stable Zn anode in aqueous ZIBs.

Mesoporous Mn-doped and carbon-coated NaTi2(PO4)3 nanocrystals as an anode material for improved performance of sodium-ion hybrid capacitors

Sodium electrochemical energy storage systems including sodium-ion battery and hybrid capacitor are attracting increasing interest in large-scale electrical energy storage due to low cost and abundant sodium resources. In particular, sodium-ion hybrid capacitor with the merits of high energy and power densities as a typical next-generation energy storage device provides a promising alternative to the currently commercial lithium-ion battery. It is highly challenging to design and prepared suitable anode materials with extraordinary performance, thereby spurring its large-scale application. Herein, mesoporous Mn-doped and carbon-coated NaTi2(PO4)3 nanocrystals are synthesized via a three-step process of solvothermal reaction, serum albumin decoration and thermal annealing. Synergistic effect rendered by NaTi2(PO4)3 particles with mesoporous structure, Mn2+ doping and ultra-thin carbon coating endows the prepared composite with facile ion/electron transportation as well as excellent reaction kinetics as an anode material for sodium-ion hybrid capacitors. In the half-cell tests, the prepared composite exhibits high reversible capacity of 116 mA h g−1 at 1 C, high-rate capability of 95 mA h g−1 at 50 C, and long-term cycling stability with high capacity of 92 mAh g−1 (88% capacity retention) after 1000 cycles at 20 C. Using the prepared composite as anode and activated carbon as cathode, the sodium-ion hybrid capacitor is assembled and it exhibits high energy/power density of 85.5 WhKg−1/5531 WKg−1. Our results indicate that Mn-doped and carbon-coated NASICON-type anodes have great potential in the sodium-based electrochemical energy storage systems.

Synthesis of NaTi2(PO4)3@C microspheres by an in situ process and their electrochemical properties

Abstract Sodium-ion batteries (SIBs) have broad applications in the field of power grid energy storage owing to their significant cost advantages. Although the 3D framework structure of NaTi2(PO4)3 with a sodium superionic conductor (NASICON) has recently been regarded as a promising anode material in SIBs, the low inherent electrical conductivity of NaTi2(PO4)3 has hindered its practical application to batteries. However, since a number of research studies have shown that the conductivities of composite materials can be improved by carbon doping or coating, the carbon-coated NaTi2(PO4)3@C (NTP@C) composite is expected to show excellent electrochemical performance in SIBs. In general, the production of NTP@C requires two steps (i.e. sample preparation and carbon coating), and the development of a one-step in situ preparation of NTP@C is desirable. In the present work, NTP@C microspheres with carbon concentrations of 1.4% and 4.95% were prepared in situ by a simple spray method followed by calcination. Of these, the NTP@C with a carbon content of about 4.95% displayed superior properties, delivering a high capacity of 105.26 mA h/g at a current rate of 5 C for the initial cycle, and presenting long-term cycling stability with a slow capacity decay of about 0.018% per cycle over 2000 cycles. The excellent electrochemical performance of the NTP@C microspheres can be attributed to the improved conductivity due to carbon coating and the enhanced stability provided by the microsphere structure. Thus, NTP@C is a promising alternative anode material for SIBs.

An aqueous rechargeable sodium−magnesium mixed ion battery based on NaTi2(PO4)3–MnO2 system

In order to develop an aqueous battery with high specific capacity, we synthesized NaTi2(PO4)3 anode material and MnO2 cathode material, and studied the electrochemical properties of the two materials in Na2SO4, MgSO4 and Na2SO4−MgSO4 mixed aqueous electrolytes, respectively. The results show that MnO2 has excellent electrochemical properties in electrolyte containing Mg2+ and its specific capacity can reach about 100 mAh g−1. Na+ and Mg2+ can be intercalated/deintercalated reversibly from the MnO2 cathode material at the same time, while the NaTi2(PO4)3 anode material can only intercalate/deintercalate Na+. Based on this, we constructed an aqueous sodium-magnesium hybrid ion battery system. The anode is carbon-coated NaTi2(PO4)3 material, and the cathode is MnO2/CNTs composite material. The electrolyte is Na2SO4 and MgSO4 mixed aqueous solution. The working voltage of the battery is about 1.4 V and its capacity can reach 97 mAh g−1.

Enhanced lithium storage performance of nanostructured NaTi2(PO4)3 decorated by nitrogen-doped carbon

NASICON-type NaTi2(PO4)3 with open framework shows great prospect in anode for aqueous lithium ion battery (ALIB). Nevertheless, low electrical conductivity and limited structure stability of NaTi2(PO4)3 in aqueous electrolyte result in poor rate and cycling performance. In this work, two strategies of carbon coating and related nitrogen doping were utilized to enhance performance of NaTi2(PO4)3 by sol-gel way, and employed as anode in ALIB. Carbon-coated NaTi2(PO4)3 with various carbon content were controlled by dosage of phenolic resin, and the best sample with carbon content of 4.9% was found. Based on this, loose nanostructured NaTi2(PO4)3 coated by nitrogen-doped carbon (NTP-2-N) was synthesized using urea as pore former and nitrogen source. NTP-2-N demonstrates excellent rate and cycling performance. It delivers the discharge capacity of 115.6, 103.4, and 74.6 mAh g−1 at 0.2, 5, and 20 C, respectively. And 80.7% of discharge capacity is retained after 1000 cycles at 5 C. The outstanding electrochemical performance of NTP-2-N mainly comes from the loose structure, carbon coating, and nitrogen doping, which protect NaTi2(PO4)3 crystal from H2O attack and accelerate the electron/Li ion transfer.

Lithium storage performance improvement of NaTi2(PO4)3 with nitrogen-doped carbon derived from polyaniline

NASICON-type NaTi2(PO4)3 has been acknowledged as a promising anode for energy storage due to high ion conductivity and low cost. Nevertheless, intrinsic low electrical conductivity of NaTi2(PO4)3 and low stability in aqueous electrolyte limit its further applications in aqueous lithium rechargeable battery. In this paper, polyaniline as carbon and nitrogen sources was employed to synthesize nitrogen-doped carbon coated NaTi2(PO4)3 (NTP-P) composite by sol-gel approach and following calcination treatment. The loose and carbon-coated structure endows NTP-P with good structure stability and improved electrochemical kinetics. Compared with glucose-derived carbon-coated NaTi2(PO4)3 composite, NTP-P exhibits superior rate and cycling performance. NTP-P with proper carbon content delivers the discharge capacity of 119.4 and 83.4 mAh g−1 at rate of 0.2 and 15 C, and its capacity retention can maintain 85.8% after 1000 cycles at 5 C. This research reveals that the integration of carbon coating and nitrogen doping by using polyaniline give an excellent method to enhance the electrochemical properties of electrode materials.

Engineering Fast Ion Conduction and Selective Cation Channels for a High-Rate and High-Voltage Hybrid Aqueous Battery.

The rechargeable aqueous metal-ion battery (RAMB) has attracted considerable attention due to its safety, low costs, and environmental friendliness. Yet the poor-performance electrode materials lead to a low feasibility of practical application. A hybrid aqueous battery (HAB) built from electrode materials with selective cation channels could increase the electrode applicability and thus enlarge the application of RAMB. Herein, we construct a high-voltage K-Na HAB based on K2 FeFe(CN)6 cathode and carbon-coated NaTi2 (PO4 )3 (NTP/C) anode. Due to the unique cation selectivity of both materials and ultrafast ion conduction of NTP/C, the hybrid battery delivers a high capacity of 160 mAh g-1 at a 0.5 C rate. Considerable capacity retention of 94.3 % is also obtained after 1000 cycles at even 60 C rate. Meanwhile, high energy density of 69.6 Wh kg-1 based on the total mass of active electrode materials is obtained, which is comparable and even superior to that of the lead acid, Ni/Cd, and Ni/MH batteries.

Revisiting the open-framework zinc hexacyanoferrate: The role of ternary electrolyte and sodium-ion intercalation mechanism

Non-flammable rechargeable aqueous sodium-ion batteries (RASB) made from natural abundant resources offer promising opportunities in large-scale energy storage, yet the low energy density as well as low voltage output and the limited cycle life hinder their practical applications. Here, we develop a high-voltage RASB based on rhombohedral zinc hexacyanoferrate as cathode materials, carbon-coated NaTi2(PO4)3 as anode materials and ternary NaClO4-H2O-polyethylene glycol (Na-H2O-PEG) as electrolyte to overcome these drawbacks. Such an RASB can deliver a high voltage output of 1.6 V with a specific energy density of 59 Wh kg−1 based on the total mass of active electrode materials. In addition, it possesses an excellent rate capability as an ultra-capacitor (2.7 kW kg−1). The capacity retention more than 91% is obtained after 100 cycles. Finally, a reversible phase transformation between rhombohedral Zn3[Fe(CN)6]2 and rhombohedral Na2Zn3[Fe(CN)6]2 that are accompanied by the insertion/extraction of sodium ion in zinc hexacyanoferrate is unveiled.

Porous carbon-coated NaTi2(PO4)3 with superior rate and low-temperature properties

Nanosized porous carbon-coated NaTi2(PO4)3 (NTP) particles with superior rate and low-temperature properties are synthesized by a hydrothermal process combined with different carbon coating steps.

Synthesis of porous carbon-coated NaTi2(PO4)3 nanocubes with a high-yield and superior rate properties

Nanosized porous carbon-coated NaTi2(PO4)3 (NTP) particles with a high yield (more than 95%) and superior rate properties are synthesized by a reflux method in ethylene glycol (EG).

Carbon-coated NaTi2(PO4)3 composite: A promising anode material for sodium-ion batteries with superior Na-storage performance

NASICON-type NaTi2(PO4)3 material has been extensively studied as a promising anode for sodium-ion batteries due to the open 3D framework with the large interstitial spaces, high theoretical capacity and small volume change during cycling process. However, the practical application of NaTi2(PO4)3 is hampered because of its low electronic conductivity. Herein, a simple approach along with post-annealing has been designed and adopted to prepare the carbon-coated NaTi2(PO4)3 (NaTi2(PO4)3@C) composite. The as-prepared anode material is characterized by XRD, SEM, TEM and Raman spectrum. The electrochemical measurements reveal that NaTi2(PO4)3@C has excellent Na-storage performances including high reversible capacity (112.6mAhg−1 at 0.2C) and good rate capability (87.1mAhg−1 at 5C). The superior electrochemical performance can be resulted from the synergistic effects of the nanosized NaTi2(PO4)3 particles and conductive carbon layer.

Flexible batteries get safer with sodium

Researchers are developing batteries and energy-storing supercapacitors that flex with the body while powering wearable and implantable medical devices. But so far these power sources have used electrolytes containing strong acids, strong bases, or toxic and flammable organic solutions, which can cause harm if they leak. Yonggang Wang, Huisheng Peng, and coworkers at Fudan University have now created bendable sodium-ion batteries containing biofriendly aqueous electrolytes (Chem 2017, DOI: 10.1016/j.chempr.2017.05.004). The batteries have a Na0.44MnO2 cathode and a carbon-coated NaTi2(PO4)3 anode in contact with one of three sodium-based electrolytes: a sodium sulfate solution, intravenous saline, or a cell culture medium. In a belt-shaped design, the cathode and anode sandwich an electrolyte-soaked separator. And a fiber-shaped design has carbon nanotube electrodes embedded with cathode and anode nanomaterials and surrounded by electrolyte. The batteries have charge capacities and power outputs per unit ...

Study on the Aqueous Hybrid Supercapacitor Based on Carbon-coated NaTi2(PO4)3 and Activated Carbon Electrode Materials

Study on the Aqueous Hybrid Supercapacitor Based on Carbon-coated NaTi₂(PO₄)₃ and Activated Carbon Electrode Materials

Second Generation Aqueous Electrolyte Electrochemical Cells for Scaled Stationary Energy Storage

The design and function of next generation aqueous electrolyte dual-intercalation energy storage devices and systems will be discussed. These system use relatively unexplored electrode interactions that exploit muti-cation reactions (eg lithium, sodium and proton interactions all can contribute to the energy storage function). The core device uses a configuration wherein the active anode material consists of a blend of carbon-coated NaTi2(PO4)3 and activated carbon and the cathode is cubic spinel l-MnO2 that has resident lithium. The electrolyte is a blend of Li+ and Na+ and hydrogen (at some states of charge) cation species, with SO4 - and OH- (at some states of charge) as the countering anions, solvated in an initially neutral pH aqueous electrolyte. Improvements to the original large-format devices first disclosed in 2011 will be disclosed, and data will be presented showing that large scale industrially packaged batteries with over 3000 Wh in capacity have be produced and qualified. Data showing the relationship between electrode thickness, current collector resistance, and overall battery performance will be shown. Systems containing packs of these batteries in the multi-kWh range have been effectively implemented in field-testing around the world. These applications include support for both smaller off-grid applications with bus voltages in the in the 20 to 100 V range, as well as, grid compatible systems with bus voltages in excess of 1000 V.

A carbon coated NASICON structure material embedded in porous carbon enabling superior sodium storage performance: NaTi2(PO4)3 as an example.

Sodium super ion conductor (NASICON) type structure materials (e.g. Na3V2(PO4)3, NaTi2(PO4)3) have been considered as promising electrode materials for sodium-ion batteries (NIBs). However, the inherent poor electronic conductivity of the NASICON type structure materials owing to their poor electronic conductivity of phosphates leads to poor cyclability and rate capability. Here, we develop a general strategy to achieve high rate capability and long cycle life by preparing "double carbon coating" NASICON NaTi2(PO4)3 using a soft-chemical method. The obtained carbon-coated NaTi2(PO4)3 within the porous carbon matrix (denoted as NTP@C@PC) imparts a reversible capability of 103 mA h g(-1) at 5 C after 5000 cycles and a rate capability of 64 mA h g(-1) at 50 C for sodium storage. The high capacity, stable cyclability and excellent rate capability of the NTP@C@PC are attributed to the advantages of the special structure: the fast Na(+)/e(-) transfer in the nanocomposites, large surface area and mesoporous nature of the 3D porous carbon matrix that facilitate the electrolyte to soak in, an intimate interaction between the particles and the carbon matrix. In addition, the 3D porous carbon matrix could effectively accommodate the volume variation during a repeated sodiation/desodiation process.

Microwave Synthesized NaTi2(PO4)3 as an Aqueous Sodium-Ion Negative Electrode

Carbon-coated NaTi2(PO4)3 was successfully synthesized via a rapid microwave-assisted method and was found to have promising electrochemical function in a neutral pH Na2SO4 aqueous electrolyte. The effects of various processing parameters, including precursor ball mill time, microwave irradiation parameters, and graphite precursor concentration, on the physical and electrochemical properties of the synthesized NaTi2(PO4)3. To further study electrochemical performance, a full test cell consisting of NaTi2(PO4)3/1 M Na2SO4/Na0.44MnO2 was assembled. The highest discharge specific capacity obtained for this material was 85 mAh/g. These results indicate that, with an appropriate amount of graphite included in the precursor mix, microwave-synthesized NaTi2(PO4)3 is a promising sodium-ion functional anode material that can be produced using an extremely appealing low-cost manufacturing process.