Aqueous Lithium-ion Batteries Research Articles

Flexible Aqueous Lithium-Ion Battery with High Safety and Large Volumetric Energy Density.

A flexible and wearable aqueous lithium-ion battery is introduced based on spinel Li1.1 Mn2 O4 cathode and a carbon-coated NASICON-type LiTi2 (PO4 )3 anode (NASICON=sodium-ion super ionic conductor). Energy densities of 63 Wh kg(-1) or 124 mWh cm(-3) and power densities of 3 275 W kg(-1) or 11.1 W cm(-3) can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li-ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self-chargeable unit is realized by integrating a single flexible aqueous Li-ion battery with a commercial flexible solar cell, which may facilitate the long-time outdoor operation of flexible and wearable electronic devices.

Advanced High-Voltage Aqueous Lithium-Ion Battery Enabled by "Water-in-Bisalt" Electrolyte.

A new super-concentrated aqueous electrolyte is proposed by introducing a second lithium salt. The resultant ultra-high concentration of 28 m led to more effective formation of a protective interphase on the anode along with further suppression of water activities at both anode and cathode surfaces. The improved electrochemical stability allows the use of TiO2 as the anode material, and a 2.5 V aqueous Li-ion cell based on LiMn2 O4 and carbon-coated TiO2 delivered the unprecedented energy density of 100 Wh kg(-1) for rechargeable aqueous Li-ion cells, along with excellent cycling stability and high coulombic efficiency. It has been demonstrated that the introduction of a second salts into the "water-in-salt" electrolyte further pushed the energy densities of aqueous Li-ion cells closer to those of the state-of-the-art Li-ion batteries.

V2O5-SiO2 hybrid as anode material for aqueous rechargeable lithium batteries

V2O5-SiO2 hybrid material was fabricated by heat-treating a mixture of H2SiO3 and V2O5. SEM, TEM, XRD, and N2 isotherm analyses were performed to characterize the morphology and structure details of the as-prepared V2O5-SiO2. The possibility of using the as-prepared V2O5-SiO2 as anode material for aqueous lithium-ion batteries was investigated. Potentiostatic and galvanostatic results indicated that the intercalation/de-intercalation of Li+ in this material in aqueous electrolyte was quasi-reversible. It was also found that a discharge capacity of up to 199.1 mAh g−1 was obtained at a current density of 50 mA g−1 in aqueous solution of 1 M Li2SO4, a value which is much higher than the available reported capacities of vanadium (+5) oxides in aqueous electrolytes.

Carbon-coated mesoporous LiTi2(PO4)3 nanocrystals with superior performance for lithium-ion batteries

Carbon-coated LiTi2(PO4)3 (LTP/C) nano- and/or microcrystals have been subjected to extensive research due to their potential application in aqueous rechargeable lithium-ion batteries (ARLBs) with enhanced electrochemical performance. In this paper, mesoporous LTP/C nanocrystals have been prepared by annealing the precursor obtained through a simple room-temperature co-precipitation method. The mesoporous LTP/C nanocrystals have been evaluated in the role of anode materials for lithium-ion batteries (LIBs) with organic and water electrolyte, respectively. After 1000 cycles at 5 and 20C, the specific discharge capacity of the LTP/C electrode with organic electrolyte retains 116.9 and 80.4mAhg−1, with capacity retention of 94.4% and 80.4%, respectively. After 1000 cycles at 1.37C, the specific discharge capacity of the LTP/C‖LiMn2O4 pouch cells with 1molL−1 Li2SO4 electrolyte retains 20.1mAhg−1, presenting a discharge voltage plateau around 1.21V and a capacity retention of 71.5%. The enhanced electrochemical performance of the mesoporous LTP/C nanocrystals makes them a promising candidate functioning as anode materials for LIBs and hybrid supercapacitors.

Ultrathin (NH4)0.5V2O5 Nanosheets as a Stable Anode for Aqueous Lithium Ion Battery

Poor cycling performance is still a big challenge for aqueous lithium ion batteries (ALIBs), in which the instability of anode is considered to be the main obstacle. Herein, single crystalline (NH4)0.5V2O5 nanosheets are prepared by a simple hydrothermal method and proposed as a novel and stable anode for ALIBs for the first time. The ALIB consisting of LiMn2O4 cathode and (NH4)0.5V2O5 anode exhibits a discharge capacity of 100 mAh g−1 (based on the mass of anode) at 30 mA g−1 and a capacity retention of ca. 100% after 200 cycles. At 1500 mA g−1, the discharge capacity of 61 mAh g−1 is maintained after 1100 cycles, indicating excellent cycling stability. As verified, the superior cycling performance of ALIB should be mainly attributed to its ultrathin nanosheet morphology and intrinsic structure stability of (NH4)0.5V2O5 anode.

NaTi2(PO4)3 Nanoparticles Embedded in Carbon Matrix as Long-Lived Anode for Aqueous Lithium Ion Battery

NaTi2(PO4)3 nanoparticles with the average size of 10–20 nm have been embedded in carbon matrix by a novel two-step approach and the composite was employed as an anode for aqueous lithium ion battery (ALIB). An ALIB consisting of a commercial LiMn2O4 cathode, NaTi2(PO4)3/C anode and Li2SO4 electrolyte has been firstly constructed. The cell delivers an average platform voltage of 1.6 V and excellent rate capability with reversible capacities of 115 mAh g−1 and 83 mAh g−1 (based on the mass of NaTi2(PO4)3) at 30 mA g−1 and 1500 mA g−1, respectively. It is interesting to note that no obvious capacity fading is observed after 300 cycles at 150 mA g−1. Even after an ultra-long cycling test up to 3600 cycles at 1500 mA g−1, 95% of the initial capacity is maintained, indicating the superior cycling stability for as-prepared NaTi2(PO4)3/C composite. The Li ion intercalation/deintercalation mechanism of NaTi2(PO4)3 anode has also been investigated. The outstanding electrochemical performance and low cost enable the NaTi2(PO4)3/C a very promising anode candidate for ALIBs.

Fluorine-free salts for aqueous lithium-ion and sodium-ion battery electrolytes

Novel fluorine-free salts for aqueous lithium-ion and sodium-ion battery electrolytes.

Enhanced resistance to oxidative decomposition of aqueous electrolytes for aqueous lithium-ion batteries.

An efficient electrolyte solution containing organic sulfonates for use in aqueous rechargeable lithium-ion batteries (ARLBs) is shown to provide a wide potential window and enable a high operating voltage for ARLBs.

Chromate conversion coated aluminium as a light-weight and corrosion-resistant current collector for aqueous lithium-ion batteries

We report chromate conversion coated (CCC) aluminium foil as a corrosion-resistant current collector in aqueous lithium-ion battery cathodes. CCC aluminium-based electrodes show better cycling stability and higher coulombic efficiency than those fabricated on stainless steel and titanium foils.

A fiber-shaped aqueous lithium ion battery with high power density

A fiber-shaped aqueous lithium ion battery is developed with ultrafast charge–discharge rates and high power density in addition to high energy density.

Synthesis and Electrochemical Performance of a Benzoquinone-Based Polymer Anode for Aqueous Lithium-Ion Batteries

Using the tetrachloro-p-benzoquinone (TCQ) monomer, poly(benzoquinonyl sulfide) (PBQS) was synthesized by a simple polycondensation reaction. The influence of the molar ratio of S to Na2S on the electrochemical performance of a PBQS anode was assessed by changing the amount of S added. The results showed that the electrochemical performance of PBQS strongly depended on the molar ratio of S to Na2S. When the molar ratio of S to Na2S was 0.4, two Cl were replaced by S, and PBQS with a stable structure was obtained. The discharge capacity of PBQS exceeded 140 mAh∙g -1 . At the same time, PBQS displayed satisfactory rate capability and excellent cyclability. Conversely, when the molar ratio of S to Na2S was decreased to 0.25, Cl was not substituted completely and the polymerization degree was low. Upon increasing the molar ratio of S to Na2S to 0.7, an unstable S―S bond may form in the polymer. The above two factors degraded the electrode performance of these materials.

The fabrication of LiMn2O4 and Na1.16V3O8 based full cell aqueous rechargeable battery to power portable wearable electronics devices

Aqueous rechargeable Lithium ion batteries (ARLBs) are considered as the safest alternatives to match the performance of current Li-ion energy storage devices. Herein, we report the configuration of a full cell ARLB with Na1.16V3O8 crystalline rods and LiMn2O4 as electrodes that deliver high efficiency and excellent rate performance. In this study Na1.16V3O8 crystalline rods synthesized by one step hydrothermal method were used as the anode and solid microspheres of LiMn2O4 synthesized by a sol–gel synthesis followed by a heat-treatment using LiOH were used as the cathode. The performance of this fabricated full cell was optimized to operate between 0V to 2.3V in aqueous electrolytes to deliver an energy density of ~240Wh/kg that was found to be better than most of the current lithium ion batteries which are based on non-flammable electrolytes. The device fabricated in this study exhibits a round trip efficiency of ~50% at the end of 100cycles with a current density of 500mAg−1. Furthermore, the charge storage mechanism in Na1.16V3O8 rods was also studied to corroborate its suitability as a potential anode material for aqueous rechargeable lithium ion batteries.

High-Rate LiTi2(PO4)3@N-C Composite via Bi-nitrogen Sources Doping.

Mesoporous LiTi2(PO4)3@nitrogen-rich doped carbon composites have been synthesized by a novel bi-nitrogen sources doping strategy. Tripolycyanamide (C3H6N6) and urea are proposed for the first time as both nitrogen and carbon sources to achieve a homogeneous nitrogen-doped carbon coating layer via an in situ method. The electrode delivers ultrahigh rate performance and outstanding cycling stability in lithium ion batteries (LIBs). In an organic electrolyte system, the electrode demonstrates high discharge capacities of 120 mAh g(-1) and 87 mAh g(-1) at 20C and 50C, respectively. Moreover, 89.5% of initial discharge capacity is retained after 1000 cycles at 10C. When used as an anode for aqueous LIBs, the electrode also demonstrates superior rate capability with the discharge capacity of 103 mAh g(-1) at 10C, corresponding to 84% of that at 1C. Outstanding cycling stability with capacity retention of 91.2% after 100 cycles at 30 mA g(-1) and 90.4% over 400 cycles at 150 mA g(-1) are also demonstrated. The uniform nitrogen-rich carbon coating and unique mesoporous structure play important roles in effectively suppressing the charge-transfer resistance and facilitating Li ion/electron diffusion, thus leading to the superior electrochemical properties.

Enhancing Cycle Stability of Lithium Iron Phosphate in Aqueous Electrolytes by Increasing Electrolyte Molarity

Aqueous lithium ion batteries (ALIBs) exhibit great potential to reduce the cost and improve the safety of rechargeable energy storage technologies. Lithium iron phosphate (LFP) cathodes have become a material of choice for many conventional, high power LIBs. However, experimental studies on LFP in aqueous lithium (Li) ion electrolytes are limited. Here, results of systematic studies are shown where it is demonstrated that the Li salt concentration of the aqueous electrolyte can significantly improve discharge capacity retention while minimally impacting rate capability, for electrodes made with a typical commercial sub‐micron sized LFP powder. Based on the postmortem analysis and the results of electrochemical characterization it is proposed that undesirable side reactions of aqueous electrolytes with LFP induce electrochemical separation of individual particles within the electrode, leading to the observed capacity fading. Increasing the salt concentration in aqueous solutions effectively reduces the concentration of water molecules in the electrolyte, which are mostly responsible for these undesirable side reactions. Similar trends observed with other cathode materials suggest that the use of concentrated aqueous electrolyte solutions offers an effective route to improve stability of aqueous Li ion batteries.

Effect of carbon coating on the electrochemical performance of LiFePO4/C as cathode materials for aqueous electrolyte lithium-ion battery

Organic electrolyte is widely used for lithium-ion rechargeable batteries but might cause flammable fumes or fire due to improper use such as overcharge or short circuit. That weakness encourages the development of tools and materials which are cheap and environmental friendly for rechargeable lithium-ion batteries with aqueous electrolyte. Lithium iron phosphate (LiFePO4) with olivine structure is a potential candidate to be used as the cathode in aqueous electrolyte lithium-ion battery. However, LiFePO4 has a low electronic conductivity compared to other cathodes. Conductive coating of LiFePO4 was applied to improve the conductivity using sucrose as carbon source by heating to 600 °C for 3 h on an Argon atmosphere. The carbon-coated LiFePO4 (LiFePO4/C) was successfully prepared with three variations of the weight percentage of carbon. From the cyclic voltammetry, the addition of carbon coatings could improve the stability of cell battery in aqueous electrolyte. The result of galvanostatic charge/discharge shows that 9 % carbon exhibits the best result with the first specific discharge capacity of 13.3 mAh g−1 and capacity fading by 2.2 % after 100 cycles. Although carbon coating enhances the conductivity of LiFePO4, excessive addition of carbon could degrade the capacity of LiFePO4.

Carbon-coated lithium titanium phosphate nanoporous microplates with superior electrochemical performance

In this study, we report a facile method to synthesize carbon-coated LiTi2(PO4)3 nanoporous microplates (LTP/C MPs) using ethylenediamine as the chelating agent and carbon source. The as-prepared LTP/C MPs with thickness of 0.4 μm consist of interconnected nanosized particles embedded in nano-thickness carbon layer and well-dispersed nanopores. The carbon layer significantly improves the electrochemical performance of LiTi2(PO4)3 microplates. LTP/C MPs deliver a reversible capacity of 121 mAh g−1 at 0.2C (1C = 138 mAh g−1) and show a remarkable capacity retention of 94.2% over 100 cycles when matched with Li metal counter electrode. It also presents excellent electrochemical properties as anode material for aqueous rechargeable lithium batteries (ARLBs). LTP/C MPs//LiMn2O4 ARLB shows a high discharge capacity of 76 mAh g−1 at 20 mA g−1 and superior rate capability. The results suggest a practical stratagem to develop a novel composite in which the carbon is coated with LiTi2(PO4)3 nanoporous microplates, which can become one of the promising electrode materials for both non-aqueous and aqueous lithium ion batteries.

Orthorhombic Lithium Titanium Phosphate as an Anode Material for Li-ion Rechargeable Battery

Rhombohedral lithium titanium phosphate, LiTi2(PO4)3, has been considered a suitable anode material for aqueous lithium-ion batteries. However, the electrochemical behaviors of pure lithium-rich polymorphs have not been described yet even Li-rich phase may show better electrochemical properties than conventional LiTi2(PO4)3 at the expense of somewhat lowered capacity. We have synthesized orthorhombic Li1.5Ti2(PO4)3 (OLTP) and rhombohedral LiTi2(PO4)3 (RLTP) via sol-gel reactions and studied their fundamental electrochemical properties using galvanostatic charge/discharge and cyclic voltammetry (CV). Their feasibility as anode materials in LiFePO4//LixTi2(PO4)3 configurations using aqueous electrolytes were also considered. The faster kinetics of the orthorhombic lithium titanium phosphate in this study were attributed to higher Li+ diffusivity and electrical conductivity, making this material an attractive alternative for conventional rhombohedral LiTi2(PO4)3.

One-pot synthesis of carbon-coated nanosized LiTi2(PO4)3 as anode materials for aqueous lithium ion batteries

In this study, a one-pot sintering process incorporating sol–gel preparation route and in-situ carbon coating was proposed for the synthesis of carbon-coated nanosized LiTi2(PO4)3. Experimental results show that the prepared LiTi2(PO4)3 particles are of high crystallinity and well-coated by turbostratic carbon. Attributed to nanosized particles and enhanced conductivity provided by turbostratic carbon coating, the carbon-coated LiTi2(PO4)3 showed high rate performance and good cycling life in aqueous electrolyte. Particularly, the carbon-coated LiTi2(PO4)3 exhibited initial specific capacities of 103 and 89 mAh g−1, and retained 80.6% and 97% of the initial capacities after 120 cycles at 1C and 10C in aqueous electrolyte, respectively. The high rate performance and good cycling life of carbon-coated LiTi2(PO4)3 in aqueous electrolyte reveal its potential as negative electrode in aqueous lithium-ion batteries for electric vehicles and industrial-scale energy storage systems.

Conducting Polymer-Coated Carbon Nanotubes As High Rate Anode Material for Rechargeable Aqueous Electrolyte Battery

Among various energy storage systems, the rechargeable battery has been proposed as one of the most promising strategy for grid-scale energy storage because of flexible power and energy characteristics, high energy conversion efficiency, and low maintenance. And, their compact size makes them well suited for use at distributed location to control the output fluctuations in local power generation. Lithium-ion batteries are being considered as one of the most promising power sources for smart grids because of their high energy density and long cycling life. However, safety and fast charging performance are still two challenging issues to be solved for their use as large-scale systems. An attractive approach to circumvent this problem is to use an aqueous electrolyte for lithium-ion batteries, which adopt a ‘rocking-chair’ concept similar to the organic lithium-ion battery. In the mid 1990s, an aqueous lithium-ion battery was proposed that uses VO2 as the anode and LiMn2O4 as the cathode. By this combination, the safety problem of the organic electrolyte is fundamentally resolved. Furthermore, since the rigorous assembly conditions are avoided, the cost is reduced greatly, compared with the non-aqueous lithium-ion battery. In this study, polypyrrole-coated carbon nanotube(CNT) was prepared by chemical oxidation polymerization of pyrrole on the surface-functionalized carbon nanotube in the presence of FeCl3. As increasing the concentration of pyrrole, the thickness of polypyrrole layer on the surface of CNT was gradually increased. Polypyrrole was very stable during the lithium and sodium doping/dedoping processes in the aqueous solution without evolution of hydrogen. When the polymers were dispersed on the surface of carbon, the discharge capacity was highly improved due to the enhanced surface area and decreased diffusion length. In the charging-discharging experiments, the decay of capacity was greatly decreased although the charging/discharging rate was increased to 10C. The conducting polymer-coated CNT showed very promising charge-discharge characteristics at high-rate region in the aqueous sodium electrolyte.

Electrochemical performance of microdisc-shaped carbon-coated lithium iron phosphate with preferentially exposed (0 1 0) planes in lithium sulfate aqueous solution

A uniformly microdisc-shaped LiFePO4/C (MD-LFP/C) material with preferentially exposed (010) planes is synthesized by heating the mixture of a microdisc-shaped precursor (MD-precursor) and polyvinylpyrrolidone(PVP) in N2 atmosphere. In particular, the MD-precursor of LiFePO4 is prepared through a simple one-pot two-step precipitation method by using ascorbic acid (AA) and PVP as morphology controlling agents. The results reveal that MD-precursor can only be obtained from the solution containing both AA and PVP. The subsequent calcination transforms the precursor into the LiFePO4/C while retaining the microdisc shape. The initial discharge capacities of the MD-LFP/C are 127, 101, 71.3 and 55.9mAhg−1 at 0.25, 2.5, 10 and 25C, respectively, in a 1.0moldm−3 Li2SO4 aqueous solution. The capacity retentions are 98% after 80 charge-discharge cycles and 80% after 200 cycles, respectively. The current work demonstrates that the MD-LFP/C composite can be prepared by an aqueous precipitation route and it has good electrochemical performance and stability for aqueous lithium-ion batteries.