Anode For Aqueous Lithium Ion Battery Research Articles

Superior electrochemical performances of LiTi2(PO4)3/C composite anode for aqueous lithium-ion battery

Superior electrochemical performances of LiTi2(PO4)3/C composite anode for aqueous lithium-ion battery

(NH4 )2 V7 O16 Microbricks as a Novel Anode for Aqueous Lithium-Ion Battery with Good Cyclability.

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH4 )2 V7 O16 with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li+ /Na+ hybrid ion batteries. The two novel full cell systems (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 and (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g-1 was demonstrated in the (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 system, whereas no capacity attenuation is observed in the (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 system. The reaction mechanisms of the (NH4 )2 V7 O16 electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH4 )2 V7 O16 can be a promising anode material for aqueous rechargeable lithium-ion batteries.

Synthesis and electrochemical performance of Li1+xTi2−xFex(PO4)3/C anode for aqueous lithium ion battery

Aqueous lithium ion batteries (ALIBs) exhibit great application prospects in energy storage system, and the anode materials is the key to the extensive development of ALIBs. In this study, Li1+xTi2−xFex(PO4)3/C (x = 0, 0.05, 0.10, 0.30) composites as anode for ALIBs were synthesized via sol-gel method. The effect of Fe doping on LiTi2(PO4)3/C properties was assessed by electrochemical measurements. In all of these composites, Li1.1Ti1.9Fe0.1(PO4)3/C (LCF-10) presents the best electrochemical properties. LCF-10 exhibits discharge capacity with 120.0 and 80.2 mAh g−1 at 0.5 and 15C, severally, increasing by 1.2 and 1.3 times compared with the original LiTi2(PO4)3/C. Besides, LCF-10 demonstrates remarkable cycling performance, whose discharge capacity retention can keep 70.2% at 5 C for 1000 cycles. Our study demonstrates that Fe doping for LiTi2(PO4)3 lattice can efficiently enhance electrochemical properties of LiTi2(PO4)3/C composite.

Earth Abundant Iron-Based Fluoro(hydroxy)Phosphate As Cathode Materials for Aqueous Batteries

The quest for an efficient cathode material for batteries have shifted the focus from oxides to polyanion based materials. Polyanions not only impart thermal and structural stability to the material but also increases the voltage of the material due to high electronegativity of the central metal atom. A lot of research has been done on PO4-based materials especially when combined with other anions like F- or OH-. Moreover, safety and cost of existing organic electrolytes force us to revisit the possible application of aqueous electrolytes. Use of aqueous electrolytes reduces the toxicity and increases the ionic conductivity by two-fold. However, the limited working voltage window of aqueous electrolytes, to avoid water splitting, makes it important to look for materials that can function efficiently in the narrow voltage window. We hereby present two case studies using earth-abundant Fe-based materials. In the first case, Na2FePO4F is demonstrated as a cathode material for aqueous sodium-ion batteries. A discharge capacity of 85 mAh g-1 at 1 mA cm-2 current density with excellent rate kinetics was observed for half-cell configurations. A full cell was assembled with NaTi2(PO4)3 anode and the Na2FePO4F | NaTi2(PO4)3 full cell delivered a reversible capacity of 85 mAh g-1 working as a 0.8 V battery. The second work is based on LiFePO4OH, which works as an anode for aqueous lithium-ion batteries (LIBs). It has been reported as a 2.5 V battery cathode material for LIBs in organic electrolytes. However, it was found to be working in the anodic range for aqueous batteries. In half-cell configuration, it delivered a discharge capacity of 153 mAh g-1 with very good rate kinetics. [Figure 1(b)] A full cell was assembled with LiFePO4 as a cathode and an energy density of 70 Wh kg-1 was observed in the first cycle. The structural characterization along with electrochemical studies will be showcased for both case studies. Figure 1: Galvanostatic (dis)charge profiles and cyclability of (a) Na2FePO4F, (b) LiFePO4OH in aqueous electrolytes in half-cell configuration. Figure 1

Tavorite LiFePO4OH hydroxyphosphate as an anode for aqueous lithium-ion batteries

In pursuit to find stable economic anode for aqueous lithium-ion batteries, tavorite structured LiFePO4OH hydroxyphosphate has been investigated in aqueous battery for the first time. First, the target compound is tested with organic electrolyte, giving the highest reported discharge capacity of 140 mAh g−1 with an Fe3+/Fe2+ redox potential of 2.6 V with excellent reversibility. LiFePO4OH is found to work as a promising anode in aqueous electrolyte with capacity ∼153 mAh g−1 (at 0.42 V vs. Ag/AgCl) with good cycling stability. An all-phosphate LiFePO4 | LiFePO4OH aqueous full cell has been fabricated having the first cycle capacity of 120 mAh g−1 (energy density ∼ 97 Wh kg−1). Tavorite LiFePO4OH forms an economic potential anode for aqueous Li-ion batteries.

Structural and Electrochemical Insights into Iron-Based Fluoro(hydroxy)Phosphate axFePO4y (A= Na, Li; Y= F, OH) As Cathode Materials for Aqueous Batteries

In search for efficient cathode materials for batteries, the focus has shifted from oxides to Polyanion based materials. Polyanions not only impart thermal and structural stability to the material but also enhance the electronegativity of the central atom which in turn increases the voltage of the material. Hence, a lot of research has been done on PO4-based materials especially when combined with other anions like F- or OH-. However, safety and cost of existing organic electrolytes force us to revisit the possible application of aqueous electrolytes. Use of aqueous electrolytes reduces the toxicity and increases the ionic conductivity by two-fold. The limited working potential range of aqueous electrolytes to avoid water splitting makes it important to look for efficient and stable electrode materials. In this pursuit, we present two case studies using earth-abundant Fe-based compounds. First, Na2FePO4F is demonstrated as a cathode material for aqueous sodium-ion batteries. A discharge capacity of 85 mAh g-1 at 1 mA cm-2 current density with excellent rate kinetics was observed for half-cell configurations. [Figure 1(a)] A full cell was assembled with NaTi2(PO4)3 anode and the Na2FePO4F | NaTi2(PO4)3 full cell delivered a reversible capacity of 85 mAh g-1 working as a 0.8 V battery (ChemElectroChem, In Press, 2018). The second work is based on LiFePO4OH which works as an anode for aqueous lithium-ion batteries (LIBs). It is reported as a 2.5 V battery cathode material for LIBs in organic electrolytes. However, it was found to be working in the anodic range for aqueous batteries. In half-cell configuration, it delivered a discharge capacity of 153 mAh g-1 with very good rate kinetics. [Figure 1(b)] A full cell was assembled with LiFePO4 as a cathode and an energy density of 70 Wh kg-1 was observed in the first cycle. The structural characterization along with electrochemical studies will be showcased for both case studies. Figure 1: Galvanostatic (dis)charge profiles and cyclability of (a) Na2FePO4F, (b) LiFePO4OH in aqueous electrolytes in half-cell configuration. Figure 1

Synthesis and performance of a graphene decorated NaTi2(PO4)3/C anode for aqueous lithium-ion batteries

Aqueous lithium-ion batteries (ALIBs) possess significant potential in applications as large-scale energy storage systems and portable power sources. Nevertheless, the inferior performance of the anodes significantly restricts the extensive applications of ALIBs. Herein, a graphene decorated NaTi2(PO4)3/C (NTP/C-G) composite was synthesized by sol-gel technology and applied as a high-performance anode for ALIBs. There was no significant impact on the crystal lattice frame of NaTi2(PO4)3 with the graphene modification. Graphene possessing a large surface area and good conductivity improved the electrochemical performance of the as-prepared NaTi2(PO4)3/C (NTP/C) composite. The discharge capacity of the NTP/C-G||LiMn2O4 cell reached 107.8, 86.2, and 76.9 mAh g−1 at 0.5, 10, and 15C, respectively, which was 12, 18.8, and 19.3 mAh g−1 higher than those for the original NTP/C||LiMn2O4 cell. Moreover, the capacity retention of the NTP/C-G||LiMn2O4 cell at 6C retained 92.1% after 1,000 cycles, which was much higher than that for the original NTP/C||LiMn2O4 cell (69.1%). The excellent performance of the graphene decorated composite was mainly attributed to the formation of conductive networks. Our data showed that graphene decorated NaTi2(PO4)3/C was a prospective anode for ALIBs.

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.

Advanced LiTi2(PO4)3/C anode by incorporation of carbon nanotubes for aqueous lithium-ion batteries

Inferior rate capability is a big challenge for LiTi2(PO4)3 anode for aqueous lithium-ion batteries. Herein, to address such issue, we synthesized a high-performance LiTi2(PO4)3/carbon/carbon nanotube (LTP/C/CNT) composite by virtue of high-quality carbon coating and incorporation of good conductive network. The as-prepared LTP/C/CNT composite exhibits excellent rate performance with discharge capacity of 80.1 and 59.1 mAh g−1 at 10 C and 20 C (based on the mass of anode, 1 C = 150 mA g−1), much larger than that of the LTP/C composite (53.4 mAh g−1 at 10 C, and 31.7 mAh g−1 at 20 C). LTP/C/CNT also demonstrates outstanding cycling stability with capacity retention of 83.3 % after 1000 cycles at 5 C, superior to LTP/C without incorporation of CNTs (60.1 %). As verified, the excellent electrochemical performance of the LTP/C/CNT composite is attributed to the enhanced electrical conductivity, rapid charge transfer, and Li-ion diffusion because of the incorporation of CNTs.

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.

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.

Synthesis and Electrochemical Performance of a Lithium Titanium Phosphate Anode for Aqueous Lithium-Ion Batteries

Lithium-ion batteries that use aqueous electrolytes offer safety and cost advantages when compared to today’s commercial cells that use organic electrolytes. The equilibrium reaction potential of lithium titanium phosphate is with respect to the standard hydrogen electrode, which makes this material attractive for use as a negative electrode in aqueous electrolytes. This material was synthesized using a Pechini type method. Galvanostatic cycling of the resulting lithium titanium phosphate showed an initial discharge capacity of and quite good capacity retention during cycling, 84% after , and 70% after at a cycling rate in an organic electrolyte. An initial discharge capacity of and capacity retention of 89% after with a coulombic efficiency above 98% was observed at a C/5 rate in -neutral . The good cycle life and high efficiency in an aqueous electrolyte demonstrate that lithium titanium phosphate is an excellent candidate negative electrode material for use in aqueous lithium-ion batteries.