Aqueous Lithium-ion Batteries Research Articles

Novel divalent organo-lithium salts with high electrochemical and thermal stability for aqueous rechargeable Li-Ion batteries

Novel electrolytes with wide electrochemical potential window and high thermal stability have great potential for aqueous rechargeable lithium-ion batteries (ARLBs). Herein, we report the synthesis of two ionic salts of lithium sulfonylbis(fluorosulfonyl)imide (LiSFSI) and lithium carbonylbis(fluorosulfonyl)imide (LiCFSI) with divalent Li+ for ARLBs. These ionic compounds are the derivatives of monovalent lithium bis(fluorosulfonyl)imide (LiFSI). The LiSFSI and LiCFSI exhibit the kinetic electrochemical stability window of ca. 3.78 and 3.52 V, respectively, which can be further expanded due to the formation of a stable solid electrolyte interface (SEI) layer. While LiFSI exhibits the kinetic electrochemical stability window of ca. 2.22 V without the formation of an SEI layer. Full ARLBs based on LiSFSI and LiCFSI electrolytes with a LiCoO2 cathode and graphite anode can deliver the specific discharge capacity of ca. 113.50 and 95.0 mAh/g, respectively, at 0.1C rate. Whereas, it is ca. 52.53 mAh/g for LiFSI at 0.1C rate. The capacity retention for LiSFSI, LiCFSI, and LiFSI based ARLBs are ca. 97.3, 89.6, and 67.8%, respectively, after 500 cycles. Furthermore, both LiSFSI and LiCFSI reveal much higher thermal stability compared to LiFSI. Thus, the derivatization of conventional ionic compounds is an effective strategy to enhance the battery performance and its lifetime.

High performance TiP2O7 nanoporous microsphere as anode material for aqueous lithium-ion batteries

This work developed a facile way to mass-produce a carbon-coated TiP2O7 nanoporous microsphere (TPO-NMS) as anode material for aqueous lithium-ion batteries via solid-phase synthesis combined with spray drying method. TiP2O7 shows great prospect as anode for aqueous rechargeable lithium-ion batteries (ALIBs) in view of its appropriate intercalation potential of −0.6 V (vs. SCE) before hydrogen evolution in aqueous electrolytes. The resulting sample presents the morphology of secondary microspheres (ca. 20 μm) aggregated by carbon-coated primary nanoparticles (100 nm), in which the primary nanoparticles with uniform carbon coating and sophisticated pore structure greatly improve its electrochemical performance. Consequently, TPO-NMS delivers a reversible capacity of 90 mA h/g at 0.1 A/g, and displays enhanced rate performance and good cycling stability with capacity retention of 90% after 500 cycles at 0.2 A/g. A full cell containing TPO-NMS anode and LiMn2O4 cathode delivers a specific energy density of 63 W h/kg calculated on the total mass of anode and cathode. It also shows good rate capacity with 56% capacity maintained at 10 A/g rate (vs. 0.1 A/g), as well as long cycle life with the capacity retention of 82% after 1000 cycles at 0.5 A/g.

Novel High-Rate Performance of Dual Carbon-Coated Li3V2(PO4)3 Materials Used in an Aqueous Electrolyte

Lithium vanadium phosphate (Li3V2(PO4)3) coated with dual carbon–citric acid and polyvinylpyrrolidone (PVP), are used as the cathode materials for the novel aqueous rechargeable lithium-ion batteries (ARLBs). Li+ diffusion coefficient of Li3V2(PO4)3/C (LVP/C) is first calculated and reported for the ARLBs. The primary discharge specific capacities of LVP/C reaches 125.8 mA h g–1 (1 C), 122.7 mA h g–1 (2 C), 113.6 mA h g–1 (5 C) and 101.6 mA h g–1 (10 C), respectively. Particularly, at 50 C (equivalent to an ampere density of 6.6 A g–1), the capacity has almost no decrease after 300 cycles. At a novel 100 C (13.2 A g–1), 94.9% of capacity retention is achieved after 1000 cycles, and the Coulombic efficiency approximates equal to 100%. Lithium vanadium phosphate with a NASCION structure is regarded as the great promising candidate material for power batteries owing to its high safety, superior structural stability, and excellent electrochemical performance.

Peering through the Stability Window

In the December issue of Chem, Feng Pan and colleagues perform a detailed study of a super-concentrated aqueous lithium-ion battery electrolyte that more than doubles the intrinsic electrochemical window of water (2.55 V compared to 1.23 V). From molecular dynamics simulations, combined with a suite of extensive characterization methods and electrochemical measurements, the authors correlate the local atomic structure of aqueous LiNO3 electrolyte to its observed enhanced electrochemical stability. They ultimately determine that the increased energy barrier for bulk water desolvation due to super-concentration is primarily responsible.

3D LiCoO2 nanosheets assembled nanorod arrays via confined dissolution-recrystallization for advanced aqueous lithium-ion batteries

Three-dimensional (3D) electrodes with freestanding feature represent the state-of-art electrode design for advanced lithium-ion batteries. Construction of 3D architectures for cathode materials, however, is still a great challenge. In this work, freestanding 3D LiCoO2 nanosheets assembled nanorod arrays are grown on carbon fabric via confined dissolution-recrystallization on the Co(CO3)1-x(OH)2x·nH2O nanowire arrays during hydrothermal treatment. The formed intermediate CoOOH nanosheets can catalyze the decomposition of H2O2 and the generated continuous oxygen bubble layer enables self-limiting dissolution-recrystallization. After final heat treatment at a low temperature of 380 °C, the obtained 3D hierarchy LiCoO2 nanorod arrays exhibit large specific capacity, excellent rate performance, and outstanding cycling stability when tested as cathode for aqueous lithium-ion batteries. It is found that the hydrothermally synthesized LiCoO2 sample without heat treatment still has some structure distortion with proton intercalation and Li+ occupancy at abnormal sites, which deteriorate its electrochemical performance. By using the 3D hierarchy LiCoO2 nanorod arrays as cathode, a flexible aqueous LiCoO2//LiTi2(PO4)3 lithium-ion battery device is successfully constructed, demonstrating superior rate performance and cycle performance.

Impact of Fe doping on performance of NaTi2(PO4)3/C anode for aqueous lithium ion battery

NaTi2(PO4)3 exhibits extensive prospect as anode for aqueous lithium ion battery (ALIB) in terms of open and stable framework. However, low conductivity of NaTi2(PO4)3 adversely affects the electrochemical performance. In this work, Na1+xTi2−xFex(PO4)3/C (x = 0.00, 0.05, 0.10, and 0.30) composites as anodes for ALIB were synthesized, and impact of Fe doping on microstructure and performance of NaTi2(PO4)3/C was examined systematically. Among composites with various content of doped Fe, Na1.1Ti1.9Fe0.1(PO4)3/C (NC-Fe-10) demonstrates outstanding electrochemical performance. NC-Fe-10 delivers the discharge capacity of 103.1 mAh g−1 at 5C and 77.7 mAh g−1 at 15C, respectively. In addition, capacity retention of NC-Fe-10 keeps 94.4% after 300 cycles at 5C, demonstrating outstanding cycling performance. This work reveals that Fe doping is an efficient method for raising the performance of NaTi2(PO4)3 as anode for ALIB.

Understanding the Exceptional Performance of Lithium‐Ion Battery Cathodes in Aqueous Electrolytes at Subzero Temperatures

AbstractLithium‐ion batteries with aqueous electrolytes can be excellent candidates for battery applications at low temperatures. In contrast to a common misconception, aqueous lithium ion batteries can operate at several tens of degrees below the freezing point of water when high concentration electrolyte solutions are utilized. Furthermore, it is reported here that the performance of intercalation cathodes in aqueous electrolytes is quite remarkable and superior to that in common organic electrolytes at very low temperatures down to about −40 °C. Here in the performance of water‐based electrolyte solutions‐based on three low‐cost inorganic salts (LiNO3, Li2SO4, and LiCl) and that of the corresponding aqueous battery systems is studied in order to understand the rate‐limiting step at sub‐zero temperatures. It is found that the charge transfer resistance is the largest impedance contributor at low temperatures. However, layered cathodes in aqueous electrolytes do not exhibit a significant increase in the charge‐transfer resistance, or a reduction in the accessible capacity during charging until the temperature is close to the solution freezing point. This is in sharp contrast to their behavior in organic electrolytes that do not support any performance below −20 °C. This different behavior explains the dramatically superior performance of lithium ion battery cathodes in water‐based electrolytes at lower temperatures.

Nanometric Water Channels in Water-in-Salt Lithium Ion Battery Electrolyte.

Lithium-ion batteries (LIBs) have been deployed in a wide range of energy-storage applications and helped to revolutionize technological development. Recently, a lithium ion battery that uses superconcentrated salt water as its electrolyte has been developed. However, the role of water in facilitating fast ion transport in such highly concentrated electrolyte solutions is not fully understood yet. Here, femtosecond IR spectroscopy and molecular dynamics simulations are used to show that bulk-like water coexists with interfacial water on ion aggregates. We found that dissolved ions form intricate three-dimensional ion-ion networks that are spontaneously intertwined with nanometric water hydrogen-bonding networks. Then, hydrated lithium ions move through bulk-like water channels acting like conducting wires for lithium ion transport. Our experimental and simulation results indicate that water structure-breaking chaotropic anion salts with a high propensity to form ion networks in aqueous solutions would be excellent candidates for water-based LIB electrolytes. We anticipate that the present work will provide guiding principles for developing aqueous LIB electrolytes.

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.

An all-vanadium aqueous lithium ion battery with high energy density and long lifespan

Aqueous Li ion batteries offer a safe and low cost alternative to their organic electrolyte counterparts; however, they usually suffer from poor cyclability due to the structural instability of electrode-active materials in the aqueous electrolytes. In the light of excellent electrochemical reversibility of vanadium-based redox couples in redox flow batteries (RFB), we propose an all-vanadium aqueous lithium ion battery (VALB) using a LiVOPO4 cathode and a VO2 anode, and a 20 m LiTFSI aqueous solution as electrolyte, respectively. This VALB battery demonstrates excellent electrochemical performances with an average operating voltage of ~1.4 V, an attractive energy density of 305 W h L−1 and 84.0 W h kg−1 based on the total active materials mass, considerably exceeding the energy density of conventional Vanadium flow battery. In addition, this battery also demonstrates an excellent cycling stability with 84% capacity retention over 1000 cycles, possibly serving for energy storage applications.

Improved lithium storage performance of NaTi2(PO4)3/C composite connected by carbon nanotubes

NaTi2(PO4)3/C (NC) composites decorated by carbon nanotubes (CNTs) were prepared via a sol-gel way, and employed as anode in aqueous lithium ion batteries. An effective conductive network was obtained by decoration of CNTs, which can interconnect NC particles. CNTs decoration has no obvious effect on lattice structure for NaTi2(PO4)3, and can enhance electrochemical properties for NC. Moreover, NC decorated by CNTs with optimal content of 8.8% (NC-CNTs-10) exhibits the highest electrochemical properties. NC-CNTs-10 delivers the discharge capacity of 96.4, 93.7, and 74.2 mAh g−1 at 0.5, 3, and 15C, respectively, with increase of 2.7, 15.1, and 38.2 mAh g−1 compared with NC. In addition, NC-CNTs-10 shows excellent cycling performance. Capacity retention for NC-CNTs-10 can reach 91.2% after 1000 cycles at a rate of 4C, 16.7% larger than that of pristine NC. Our study reveals that CNTs decoration is a simple way to raise electrochemical properties for NaTi2(PO4)3/C in aqueous lithium ion batteries.

Naphthol bis-indole derivative as an anode material for aqueous rechargeable lithium ion battery

Naphthol bis-indole derivative as an anode material for aqueous rechargeable lithium ion battery

Good Lithium-Ion Insertion/Extraction Characteristics of a Novel Double Metal Doped Hexa-Vanadate Compounds Used in an Inorganic Aqueous Solution

We report a potassium doped NaV6O15 anode with enhanced electrochemical performance, used for aqueous rechargeable lithium ion battery. Different Na1–xKxV6O15 (x = 0, 0.1, 0.2, 0.3) compounds are prepared and characterized using X-ray diffraction patterns ensuring potassium doping. The electrochemical performances of the various potassium doped anodes NaV6O15, Na0.9K0.1V6O15, Na0.8K0.2V6O15, and Na0.7K0.3V6O15 are evaluated by cyclic voltammetry and galvanostactic charge/discharge methods. The results suggest that potassium-doping has a positive effect on the electrochemical performance of aqueous rechargeable lithium ion batteries. The anode Na0.8K0.2V6O15 is found to be optimized potassium doped anode materials for aqueous rechargeable lithium ion battery. The Na0.8K0.2V6O15 anode displays enhanced cycling and rate performances, an initial specific capacity of 218 mAhg–1, and 133 mAhg–1 is delivered after 50 cycles (61% capacity retention) at the current density of 100 mAg–1. The potassium doping has in...

Synthesis of 2‐[1H‐indol‐2‐yl(1H‐indol‐3‐yl)methyl]phenol and Its Application in Aqueous Rechargeable Lithium‐Ion Batteries

AbstractThe present work focuses on a novel synthetic approach for a bis‐Indole derivative and its applications in energy storage devices. Here, an aqueous rechargeable lithium ion battery (ARLIB) with organic active material electrodes of inexpensive and sustainable, bis‐indole derivative called 2‐[1H‐indol‐2‐yl(1H‐indol‐3‐yl)methyl]phenol (b‐IMP) and Lithiated quinizarin (Li‐QZ) are used as cathode and anode respectively in saturated Li2SO4supporting electrolyte. The electrochemical activities of these organic redox active materials are studied using cyclic voltammetry, galvanostatic charge potential limit and potentiostatic electrochemical impedance spectroscopy methods. The cell b‐IMP | Sat. Li2SO4 | Li‐QZ has delivered an exceptionally better cell‐voltage of 0.7 V with a discharge capacity of 292 mA h g−1 with 92% columbic efficiency even after 300 cycles. The cell comprises of b‐IMP and Li‐QZ as cathode and anode materials respectively, which exhibits remarkable cyclizability with good discharge capacity and thus signifies a major advance in organic ARLIBs.

(Battery Division Technology Award) Aqueous Li(Na) –ion Batteries as Potential Stationary Power

The stability and reliability of electricity grids requires a continuous balance between energy supply and demand. Renewable generation, such as solar and wind, is intermittent, which causes sudden and unanticipated changes to power output and contributes to electricity grid instability. The aqueous lithium-ion battery (LIB) or sodium-ion battery (SIB) may solve both the safety problem associated with lithium-ion batteries that use highly toxic and flammable organic solvents, and the poor cycling life associated with commercialized aqueous rechargeable batteries including lead-acid and nickel-metal hydride systems. Aqueous LIB and SIB have been demonstrated to be one of the most promising stationary power sources for the sustainable energy such as wind and solar power. As early as in 2005, we developed a new concept hybrid electrochemical supercapacitor in which a Li-ion intercalated compound was used as a positive electrode in combination with an activated carbon negative electrode in a Li2SO4 aqueous electrolyte (ZL. 200510025269.6). The negative electrode stores charge through a reversible nonfaradaic reaction of Li-ion on the surface of an activated carbon. The positive electrode utilizes a reversible faradic reaction of Li-ion insertion/extraction in the lithium-ion intercalated compounds. A hybrid cell consisting of a spinel LiMn2O4 positive and an AC negative electrode shows excellent reversibility with a sloping voltage profile from 0.8 to 1.8 V at an average voltage near 1.3 V, and delivers an 8 Wh/kg of 60000 F practical cell. In order to improve the specific energy, we employed LiTi2(PO4)3, but the cell shows poorer cycling stability compared with the pure AC anode. We analyzed the stability of electrode materials in aqueous electrolytes extensively. We found that, in the presence of oxygen, the discharged state of lithium-ion intercalated compounds (LIC) of all negative electrode materials suitable for aqueous lithium-ion batteries reacts with water and O2, with no dependence on the pH value of the electrolyte, which is mainly responsible for the capacity fading of aqueous lithium-ion batteries during charge/discharge cycling. By eliminating the O2 (using a sealed cell), adjusting the pH values of the electrolyte, and using carbon-coated electrode materials; the LIB shows much cycling stability. A commercialized hybrid LIB shows a specific energy of ca. 30 Wh/kg, and exhibits a good cycling stability over 3500 cycles.

The development in aqueous lithium-ion batteries

To meet the growing energy demands, it is urgent for us to construct grid-scale energy storage system than can connect sustainable energy resources. Aqueous Li-ion batteries (ALIBs) have been widely investigated to become the most promising stationary power sources for sustainable energy such as wind and solar power. It is believed that advantages of ALIBs will overcome the limitations of the traditional organic lithium battery in virtue of the safety and environmentally friendly aqueous electrolyte. In the past decades, plentiful works have been devoted to enhance the performance of different types of ALIBs. In this review, we discuss the development of cathode, anode and electrolyte for acquiring the desired electrochemical performance of ALIBs. Also, the main challenges and outlook in this field are briefly discussed.

Effect of Sn doping on the electrochemical performance of NaTi2(PO4)3/C composite

In this paper, NaTi2-xSnx(PO4)3/C (x = 0.0, 0.2, 0.3, and 0.4) composites were fabricated via facile sol-gel method, and employed as anodes for aqueous lithium ion batteries. Effect of Sn doping with various content on electrochemical properties of NaTi2(PO4)3/C was investigated systematically. Sn doping on Ti site has no obvious effect on the lattice structure and morphology of NaTi2(PO4)3/C. Among all samples, NaTi1.7Sn0.3(PO4)3/C (NC-Sn-3) demonstrates the best electrochemical properties. NC-Sn-3 exhibits the outstanding rate performance, delivering a discharge capacity of 103.3, 95.2, and 87.4 mAh g−1 at 0.5, 7, and 20 °C, respectively, 1.7, 30.5, and 56.2 mAh g−1 larger than those of pristine NaTi2(PO4)3/C. In addition, NC-Sn-3 shows excellent cycling performance with the capacity retention of 80.6% after 1000 cycles at 5 °C. This work reveals that Sn doped NaTi2(PO4)3/C with outstanding electrochemical properties are potential anode for aqueous lithium ion batteries.

N-doped carbon coated LiTi2(PO4)3 as superior anode using PANi as carbon and nitrogen bi-sources for aqueous lithium ion battery

N-doped carbon coated LiTi2(PO4)3 composites were synthesized by polyaniline (PANi) as carbon and nitrogen bi-sources, and used as anode for aqueous lithium ion battery (ALIB). High-quality N-doped carbon layers were achieved to modify LiTi2(PO4)3 crystal. ALIB using as-synthesized LiTi2(PO4)3@C-N as anode exhibited superior rate performance. It delivered discharge capacities of 122.4, 105.8, and 95.3 mAh g−1 at rates of 0.2, 10, and 20C, respectively, much higher than those (97.4, 61.1, and 43.9 mAh g−1) of LiTi2(PO4)3/C using sucrose as carbon source. Furthermore, LiTi2(PO4)3@C-N anode demonstrated outstanding cycling performance with a capacity retention of 82.1% after 1000 cycles at 2C, while only 56.3% of capacity retention was kept for that using sucrose as carbon source. The excellent electrochemical performances of LiTi2(PO4)3@C-N are mainly attributed to good dispersion, proper carbon layer, and nitrogen doping, further accelerating the charge transfer and diffusion of Li ions/electrons.

All-NASICON LVP-LTP aqueous lithium ion battery with excellent stability and low-temperature performance

A rechargeable aqueous lithium ion battery containing all-NASICON type cathode and anode materials is proposed and developed for the first time. In the design, LiTi2(PO4)3 and Li3V2(PO4)3 serve as the anode and cathode, respectively, which can fulfill the electrochemical window of aqueous solutions and ensure fast lithium ion diffusion into/from electrodes thus provide a safe, fast, inexpensive aqueous lithium ion battery. However, the capacity fading of the Li3V2(PO4)3 is extremely serious in common aqueous solutions. Therefore, the fading mechanism is systematically investigated and “water in salt” aqueous electrolyte is introduced to further solve the fading problem. Consequently, the cycling stability is greatly improved. Even after 100 cycles at 0.1 C, there remains a high reversible capacity of 104 mAh g−1, which is 83.2% of the initial discharge capacity. Furthermore, benefiting from the all-NASICON electrodes construction and super low freezing point of “water in salt” electrolyte, the aqueous battery deliveries remarkable low-temperature performance. It is a powerful and safe candidate for extreme-situation energy storage applications.

Facile synthesis of TiP2O7/C nanoparticles as a competitive anode for aqueous lithium ion batteries

TiP2O7 is an applicable anode for aqueous Li ion batteries (ALIBs) for its suitable potential and competitive capacity. However, inferior cycling performance and rate capability owing to the poor ionic and electronic conductivities have greatly restricted its application in ALIBs. To tackle these issues, the strategies of nanostructuring and high quality carbon coating were developed in this work. TiP2O7/C nanoparticles with a size of ca. 50 nm have a high surface area of 41.07 m2 g−1. In this composite, TiP2O7 nanoparticle is well coated by a uniform carbon layer (thickness of ca. 10 nm and carbon content of 7.65 wt%). The as-obtained TiP2O7/C composite shows an excellent cycling performance (90.6% capacity retention after 100 cycles at 30 mA g−1 and 97.3% capacity retention after 600 cycles at 750 mA g−1) and superior rate capability (97 mAh g−1 at 30 mA g−1 and 78 mAh g−1 at 300 mA g−1). It is found that the intrinsically stable structure of TiP2O7 nanoparticles and the uniform carbon coating greatly contributed to their superior electrochemical properties in aqueous electrolyte.