Enhancement of Li-ion battery performance of graphite anode by sodium ion as an electrolyte additive

First-principles study of two-dimensional C-silicyne nanosheet as a promising anode material for rechargeable Li-ion batteries

Li-ion batteries are one of the sustainable alternatives to meet the growing energy demands of an increasing population. However, finding a suitable negative electrode is key for improving battery performance. In the present work, first principles-based investigations are carried out to explore the capability of a planar 2D C-silicyne nanosheet - which is a Si analogue of α-graphyne having -CC- substitution - as an anode for improving the performance of Li-ion batteries. Thermally and dynamically stable C-silicyne sheets exhibit a metallic nature as inferred from the density of states studies. The average adsorption energies for sequential adsorption of the Li atom over the monolayer range from -1.35 to -0.46 eV, implying favourable interactions between the monolayer and the Li atom which indicate that during the lithiation process, clustering amongst the metal atoms is not preferred. The energy barrier for the migration of Li-ions is 0.21 eV, indicating an active charge/discharge process. A high storage capacity of 836.07 mA h g^-1 and a working potential of 0.60 V is obtained. A negligible amount of volume change of the C-silicyne monolayer after full lithiation is observed which implies good cyclability. All these outcomes imply that C-silicyne nanosheets are a potential anode material for next-generation LIBs.

Amorphous Si1-yCy composite anode materials: ab initio molecular dynamics for behaviors of Li and Na in the framework

Although amorphous Si/C composite anode materials with various types of nanostructures Si/C materials have been experimentally proposed for rechargeable ion batteries for their structural durability, the atomistic mechanism primarily suggesting Li and Na monovalent ion intercalation into an amorphous Si/C composite matrix has not theoretically been understood to explore the thermodynamic and kinetic features of the a-Si/C composite phase regarding the effects on the carbon addition to an amorphous Si matrix. In this work, systematic ab initio molecular dynamics calculations (AIMDs) were conducted to identify electrochemical intercalation reactions involved in nanostructure evolutions, which correspond to favorable ion-intercalated formations, volume expansions, pair correlations, charge transfers, and diffusion behaviors of metals in a-M_xSi_1-yC_y (M_x: Li_x and Na_x) alloys with increasing x contents of atomic concentrations. AIMDs using the a-Si_1-yC_y composite phase might allow one to have an atomic-level understanding of the composite phase and further insightful comprehension of any implementations such as the controlled ratio of the Si_1-yC_y composite and multivalent ions inserted into the framework.

A review on energy chemistry of fast-charging anodes

Fundamentals, challenges, and solutions towards fast-charging graphite anodes are summarized in this review, with insights into the future research and development to enable batteries suitable for fast-charging application.

Synergistic modification of commercial TiO2 by combined carbon sources of citric acid and sodium carboxymethyl cellulose

The performance of a commercial TiO₂ anode was optimized by adjusting the ratio of citric acid and CMC-Na to modulate the carbon and Na⁺-doping content.

Uniform Surface Modification of Li2ZnTi3O8 by Liquated Na2MoO4 To Boost Electrochemical Performance

Poor ionic and electronic conductivities are the key issues to affect the electrochemical performance of Li₂ZnTi₃O₈ (LZTO). In view of the water solubility, low melting point, good electrical conductivity, and wettability to LZTO, Na₂MoO₄ (NMO) was first selected to modify LZTO via simply mixing LZTO in NMO water solution followed by calcining the dried mixture at 750 °C for 5 h. The electrochemical performance of LZTO could be enhanced by adjusting the content of NMO, and the modified LZTO with 2 wt % NMO exhibited the most excellent rate capabilities (achieving lithiation capacities of 225.1, 207.2, 187.1, and 161.3 mAh g^-1 at 200, 400, 800, and 1600 mA g^-1, respectively) as well as outstanding long-term cycling stability (delivering a lithiation capacity of 229.0 mAh g^-1 for 400 cycles at 500 mA g^-1). Structure and composition characterizations together with electrochemical impedance spectra analysis demonstrate that the molten NMO at the sintering temperature of 750 °C is beneficial to diffuse into the LZTO lattices near the surface of LZTO particles to yield uniform modification layer, simultaneously ameliorating the electronic and ionic conductivities of LZTO, and thus is responsible for the enhanced electrochemical performance of LZTO. First-principles calculations further verify the substitution of Mo⁶⁺ for Zn²⁺ to realize doping in LZTO. The work provides a new route for designing uniform surface modification at low temperature, and the modification by NMO could be extended to other electrode materials to enhance the electrochemical performance.

Intercalation behaviour of magnesium into natural graphite using organic electrolyte systems

Use of natural graphite based electrodes as insertion anodes in rechargeable magnesium-ion batteries.

Could Borophene Be Used as a Promising Anode Material for High-Performance Lithium Ion Battery?

The rapid development of electronic products has inspired scientists to design and explore novel electrode materials with an ultrahigh rate of charging/discharging capability, such as two-dimensional (2-D) nanostructures of graphene and MoS2. In this study, another 2-D nanosheet, that is a borophene layer, has been predicted to be utilized as a promising anode material for high-performance Li ion battery based on density functional theory calculations. Our study has revealed that Li atom can combine strongly with borophene surface strongly and easily, and exist as a pure Li(+) state. A rather small energy barrier (0.007 eV) of Li diffusion leads to an ultrahigh diffusivity along an uncorrugated direction of borophene, which is estimated to be 10(4) (10(5)) times faster than that on MoS2 (graphene) at room temperature. A high Li storage capacity of 1239 mA·h/g can be achieved when Li content reaches 0.5. A low average operating voltage of 0.466 V and metallic properties result in that the borophene can be used as a possible anode material. Moreover, the properties of Li adsorption and diffusion on the borophene affected by Ag (111) substrate have been studied. It has been found that the influence of Ag (111) substrate is very weak. Li atom can still bind on the borophene with a strong binding energy of -2.648 eV. A small energy barrier of 0.033 eV can be retained for Li diffusion along the uncorrugated direction, which can give rise to a high Li diffusivity. Besides, the performances of borophene-based Na ion battery have been explored. Our results suggest that an extremely high rate capability could be expected in borophene-based Li ion battery.

Understanding undesirable anode lithium plating issues in lithium-ion batteries

Lithium-ion batteries, carbon anode, lithium plating, characterization techniques, sluggish intercalation kinetics.

Negative electrodes for Na-ion batteries

Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

Electrochemical lithiation performance and characterization of silicon-graphite composites with lithium, sodium, potassium, and ammonium polyacrylate binders

Poly(acrylic acid) (PAH), which is a water soluble polycarboxylic acid, is neutralized by adding different amounts of LiOH, NaOH, KOH, and ammonia (NH4OH) aqueous solutions to fix neutralization degrees. The differently neutralized polyacid, alkali and ammonium polyacrylates are examined as polymeric binders for the preparation of Si-graphite composite electrodes as negative electrodes for Li-ion batteries. The electrode performance of the Si-graphite composite depends on the alkali chemicals and neutralization degree. It is found that 80% NaOH-neutralized polyacrylate binder (a pH value of the resultant aqueous solution is ca. 6.7) is the most efficient binder to enhance the electrochemical lithiation and de-lithiation performance of the Si-graphite composite electrode compared to that of conventional PVdF and the other binders used in this study. The optimum polyacrylate binder highly improves the dispersion of active material in the composite electrode. The binder also provides the strong adhesion, suitable porosity, and hardness for the composite electrode with 10% (m/m) binder content, resulting in better electrochemical reversibility. From these results, the factors of alkali-neutralized polyacrylate binders affecting the electrode performance of Si-graphite composite electrodes are discussed.