Search

Inorganic materials form an emerging class of water‐soluble binders for battery applications. Their favourable physicochemical properties, such as intrinsic ionic conductivity, high thermal stability (>1000 °C), and compatibility to coat a diverse range of electrode materials make them useful binders for lithium‐ion and sodium‐ion batteries. Li and Na containing phosphates and silicates are attractive choices as multifunctional inorganic aqueous binders (IABs). This review discusses these binders' structural, thermal, and ionic properties, followed by exploiting their ionically conducting nature for all‐solid‐state batteries. Subsequently, the application of these compounds as binders and surface coating agents for different anodes and cathodes in lithium‐ion and sodium‐ion batteries is discussed. Eventually, a first evaluation of their environmental impacts and economic aspects is presented as well. [ABSTRACT FROM AUTHOR]

Cost, safety, and cycle life have emerged as prime concerns to build robust batteries to cater to the global energy demand. These concerns are impacted by all battery components, but the realizable energy density of lithium‐ion batteries (LIBs) is limited by the performance of cathodes. Thus, cathode materials have a significant role to play in advancing the performance and economics of secondary batteries. To realize next generation Li‐ion and post Li‐ion batteries, a variety of cathode insertion materials have been explored, but finding a cost effective and stable cathode material that can deliver high energy density has been a daunting task. Oxide cathode materials are ubiquitous in commercial applications, as they can deliver high capacity. In comparison, polyanionic insertion materials can offer tuneable (high) redox potential, operational safety, and structural as well as thermal stability. Indeed, a wide range of polyanionic materials like phosphates, borates, sulfates, and their complexes have been reported. In this article, the alkali metal fluorophosphates class of polyanionic cathodes for secondary batteries is discussed. The various reported fluorophosphate insertion materials are discussed in terms of their electrochemical and electrocatalytic properties. The historical overview, recent progress, and remaining challenges for polyanionic fluorophosphates are presented along with suggested future research directions and potential application. [ABSTRACT FROM AUTHOR]

Rechargeable batteries have emerged as ubiquitous and indispensable technologies of the 21st century, propelling myriads of consumer electronics and ushering a new era of electric vehicles and stationary grid storage. Since the commercialization of Li‐ion batteries by SONY (approximately in the year 1991), the secondary battery sector has seen unprecedented growth with diverse applications touching global populations across socioeconomic strata. There is a steady quest to develop a wide range of batteries to cater diverse global demands from milliwatt‐scale electronics to megawatt‐scale grid‐storage applications. In this journey, Li‐ion batteries are complemented by various post‐Li‐ion chemistry (e.g., Na+, K+, Mg2+, Ca2+, and Al3+‐ion batteries), conversion mechanism‐based systems (e.g., Li–S, Na–S, and Li–O2) as well as renewed development of pre‐Li‐ion era technologies like aqueous batteries. Cathodes sit at the core with command over the net cost and performance of batteries. Various polyanionic cathodes have been developed to date, often guided by structure of naturally occurring minerals. One such mineral system is alluaudite, named after French geologist François Alluaud. The current article portrays the discovery and development of the alluaudite class of polyanionic cathode materials for rechargeable batteries. The structure and electrochemical properties of various alluaudite insertion materials are gauged along with possible future perspectives. [ABSTRACT FROM AUTHOR]

Lead lithium titanate (PbLi2Ti6O14) was synthesized by combustion route restricting the annealing at 900°C to just 1 minute. Rietveld analysis confirmed orthorhombic (Cmca) product phase with an average particle size ~200 nm and surface area of 2 m²/g forming secondary porous particles. From bond valence site energy (BVSE) calculations, 1 D ionic conduction was found along c axis with low activation energy (0.23 eV). AC conductivity analysis revealed a bulk conductivity of 2 x 10-7 S.cm-1 at room temperature and 1 x 10-4 S.cm-1 at 200°C with a switch from extrinsic 1D to intrinsic 2D mechanism at 150°C. Li+ diffusion coefficient was calculated to be in the order of 10-12 cm2.s-1. More than 4 lithium (per f.u.) could be reversibly (de)inserted delivering capacity over 160 mAh/g with good cycling retention over 1000 cycles. With a feasible rapid synthesis, good diffusional and electrochemical behavior especially high rate capability, PbLi2Ti6O14 can act as a safe 1.35 V anode for rechargeable Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Efficient energy storage is a driving factor propelling myriads of mobile electronics, electric vehicles and stationary electric grid storage. Li‐ion batteries have realized these goals in a commercially viable manner with ever increasing penetration to different technology sectors across the globe. While these electronic devices are more evident and appealing to consumers, there has been a growing concern for micro‐to‐mega grid storage systems. Overall, the modern world demands energy in ‘terawatt’ scale. It needs a multipronged approach with alternate technologies complementing the Li‐ion batteries. One such viable approach is to design and implement Na‐ion batteries. With the uniform geographical distribution, abundance and materials economy of Na resources as well as a striking operational similarity to Li‐ion batteries, Na‐ion batteries have commercial potential, particularly for applications unrestricted by volumetric/gravimetric energy density. In pursuit of the development of Na‐ion batteries, suites of oxides, sulfides, fluorides, and polyanionic materials have been reported in addition to several organic complexes. This article gives an overview of recent progress in polyanionic framework compounds, with emphasis on high‐voltage candidates consisting of earth abundant elements. Guided by ternary phase diagrams, recently discovered and potential cathode candidates will be discussed gauging their performance, current status, and future perspectives. [ABSTRACT FROM AUTHOR]

A porous, hollow, microspherical composite of LiMnO and LiMnCoNiO (composition: LiMnNiCoO) was prepared using hollow MnO as the sacrificial template. The resulting composite was found to be mesoporous; its pores were about 20 nm in diameter. It also delivered a reversible discharge capacity value of 220 mAh g at a specific current of 25 mA g with excellent cycling stability and a high rate capability. A discharge capacity of 100 mAh g was obtained for this composite at a specific current of 1000 mA g. The high rate capability of this hollow microspherical composite can be attributed to its porous nature. [ABSTRACT FROM AUTHOR]

Rechargeable batteries have been the torchbearer electrochemical energy storage devices empowering small-scale electronic gadgets to large-scale grid storage. Complementing the lithium-ion technology, sodium-ion batteries have emerged as viable economic alternatives in applications unrestricted by volume/weight. What is the best performance limit for new-age Na-ion batteries? This mission has unravelled suites of oxides and polyanionic positive insertion (cathode) compounds in the quest to realize high energy density. Economically and ecologically, iron-based cathodes are ideal for mass-scale dissemination of sodium batteries. This Perspective captures the progress of Fe-containing earth-abundant sodium battery cathodes with two best examples: (i) an oxide system delivering the highest capacity (∼200 mA h/g) and (ii) a polyanionic system showing the highest redox potential (3.8 V). Both develop very high energy density with commercial promise for large-scale applications. Here, the structural and electrochemical properties of these two cathodes are compared and contrasted to describe two alternate strategies to achieve the same goal, i.e., improved energy density in Fe-based sodium battery cathodes. [ABSTRACT FROM AUTHOR]

Rechargeable batteries based on Li and Na ions have been growing leaps and bounds since their inception in the 1970s. They enjoy significant attention from both the fundamental science point of view and practical applications ranging from portable electronics to hybrid vehicles and grid storage. The steady demand for building better batteries calls for discovery, optimisation and implementation of novel positive insertion (cathode) materials. In this quest, chemists have tried to unravel many future cathode materials by taking into consideration their eco-friendly synthesis, material/process economy, high energy density, safety, easy handling and sustainability. Interestingly, sulfate-based cathodes offer a good combination of sustainable syntheses and high energy density owing to their high-voltage operation, stemming from electronegative SO42− units. This review delivers a sneak peak at the recent advances in the discovery and development of sulfate-containing cathode materials by focusing on their synthesis, crystal structure and electrochemical performance. Several family of cathodes are independently discussed. They are 1) fluorosulfates [AMSO4F], 2) bihydrated fluorosulfates [AMSO4F ⋅ 2H2O], 3) hydroxysulfate [AMSO4OH], 4) bisulfates [A2M(SO4)2], 5) hydrated bisulfates [A2M(SO4)2 ⋅ nH2O], 6) oxysulfates [Fe2(SO4)2O] and 7) polysulfates [A2M2(SO4)3]. A comparative study of these sulfate-based cathodes has been provided to offer an outlook on the future development of high-voltage polyanionic cathode materials for next-generation batteries. [ABSTRACT FROM AUTHOR]

Recently unveiled 'alkali metal fluorosulphate (AMSOF)' class of compounds offers promising electrochemical and transport properties. Registering conductivity value as high as 10 S cm in NaMSOF phases, we explored the fluorosulphate group to design novel compounds with high Li-ion conductivity suitable for solid electrolyte applications. In the process, we produced sillimanite-structured LiZnSOF by low temperature synthesis ( T ≤ 300 °C). Examining this phase, we accidentally discovered the possibility of improving the ionic conductivity of poor conductors by forming a monolayer of ionic liquid at their particle surface. This phenomenon was studied by solid-state NMR, XPS and AC impedance spectroscopy techniques. Further, similar trends were noticed in other fluorosulphate materials like tavorite LiCoSOF and triplite LiMnSOF. With this study, we propose 'ionic liquid grafting' as an interfacial route to enable good Li-ion conductivity in otherwise poor conducting ceramics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lead-based perovskites (PbTiO 3 , PbZrO 3) are shown as anodes for secondary batteries. • Charge storage in perovskites occurs by irreversible conversion (PbII to Pb0) followed by reversible (de)alloying reaction. • TEM confirms the reversibility of (de)alloying reaction of Pb with alkali (Li,Na). • PbTiO 3 delivers capacity ~300 mAh/g with low voltage (~0.5 V) operation for both Li-ion and Na-ion batteries. Lead-based perovskites (PbTiO 3 and PbZrO 3) are introduced as novel anode materials for non-aqueous M-ion rechargeable batteries (M = Li, Na, K). These compounds were scalably prepared by conventional solid-state (dry) and combustion (wet) routes. Charge storage in these perovskites involves a standard conversion (PbII → Pb0) followed by reversible Li-Pb/Na-Pb/K-Pb (de)alloying reaction. The oxide matrix (M 2 O, TiO 2 etc.) phase is crucial for reversibility of Pb alloying reaction, as pristine PbO fails fast. The conversion-alloying reaction mechanism has been verified by ex situ electron microscopy (TEM) study. PbTiO 3 delivered 410 mAh/g capacity in the first charge vs. Li/Li+ and Na/Na+, while around 180 mAh/g capacity was observed vs. K/K+. Particularly, PbTiO 3 forms a robust anode for sodium-ion batteries with maximum charge extracted under low voltage (below 0.8 V vs. Na/Na+, 275 mAh/g). Similar electrochemical activity was also noticed for other perovskites like PbZrO 3 that confirms Pb-based (simple and mixed) perovskites can form a potential class of battery anode materials. [ABSTRACT FROM AUTHOR]

"Building better batteries" remains an ongoing process to cater diverse energy demands starting from small‐scale consumer electronics to large‐scale automobiles and grid storage. While Li‐ion batteries have carried this burden over the last three decades, the ever‐growing and highly diverse applications (based on size, energy‐density, and stationary vs mobile usages) have led to an era of "beyond lithium‐ion batteries." In this postlithium‐battery era, sodium‐ion batteries (NIBs) have emerged as a pragmatic option particularly for large‐scale applications. They attract attention due to the abundance and uniform geographic distribution of sodium‐based minerals, materials/process economy, and well‐known (de)intercalation mechanisms, in particular for stationary applications independent of size/weight restriction. Parallel to the Li‐ion batteries, the cathode (positive electrode) plays a key role in overall performance, leading to the exploration of various layered and 3D framework insertion materials. While layered oxides deliver high capacity, polyanionic hosts offer structural stability, operational safety, and tunable redox potentials. It can be further exploited in "mixed polyanion" cathode materials combining more than one kind of polyanion units. This article focuses on mixed polyanionic cathode materials for NIBs. It renders a sneak‐peek on suites of mixed polyanionic insertion materials discussing their structure, overall electrochemical performance, and future perspectives. The polyanionic family of battery electrodes offers structural stability, operational safety, and tunable redox potentials. Going a step further, "mixed polyanionic cathode materials" form a niche sector combining more than one kind of polyanion units. This article renders a sneak‐peek on suites of mixed polyanionic cathode materials for sodium‐ion batteries discussing their structure, overall electrochemical performance, and future perspectives. [ABSTRACT FROM AUTHOR]

Mixed-metal Li2MxFe1-xP2O7 (M: Mn, Co, Mg) cathode materials for lithium ion batteries with a monoclinic structure (space group P21/c) exhibit unusually high Fe3+/Fe2+ redox potentials close to 4.0 V vs Li/Li+. [ABSTRACT FROM AUTHOR]

Li 4 Ti 5 O 12 spinel is a popular zero-strain negative insertion material capable of acting as a host for both Li + and Na + ions. For efficient electrochemical activity, it is key to produce Li 4 Ti 5 O 12 spinel in nanoscale morphology with reduced diffusion barrier. Here, we report (ultrasonic) sonochemical synthesis as a novel energy-miser route to achieve spherical 100–150 nm spinel particles with restricted annealing for just 2 h. Synchrotron diffraction analysis reveals the formation of phase-pure spinel product. The resulting Li 4 Ti 5 O 12 yields desirable (de)intercalation of Li + (at 1.55 V) and Na + (at 0.9 V) ions with excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Perovskite ceramic oxides (ABO 3) have emerged as strong contenders against graphite anodes in non-aqueous metal-ion batteries. Exploring perovskites, we studied lithium insertion in barium lead oxide (BaPbO 3) and strontium lead oxide (SrPbO 3) perovskites, where lead (Pb4+) occupies the B-site. BaPbO 3 and SrPbO 3 , mass produced by solid-state or solution-combustion route, delivered reversible capacities upto 333 mAh/g and 339 mAh/g corresponding to 4.3 and 4.9 lithium uptake, respectively at room temperature. Among them, BaPbO 3 showed stable cycling for 50 cycles. Furthermore, at 50 ⁰C, BaPbO 3 delivers a first charge capacity of 382 mAh/g (or 5.6 lithium per formula unit) maintaining excellent stability beyond 50 cycles. Ex situ diffraction and microscopy studies confirm charge storage occurs via initial conversion (PbIV/PbII → Pb0) followed by reversible (de)alloying (Li–Pb) reaction. These results showcase perovskites as a promising family of Li-ion battery anodes. [ABSTRACT FROM AUTHOR]

Common preparation methods of manganese-based Li-rich layered oxides include co-precipitation, combustion, spray pyrolysis, and molten salt synthesis. Herein, we present a facile new reactive-templating route to prepare manganese-based lithium-rich Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 using β−MnO 2 nanorod, which plays a dual role as reactive template as well as Mn-source. Rietveld refinement and electron diffraction patterns confirm the formation of phase pure, highly crystalline Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 with two integrated layered components of 0.5(Li 2 MnO 3).0.5(LiMn 1/3 Ni 1/3 Co 1/3 O 2). Electron microscopy studies reveal the formation of anisotropic rod-like crystals of 0.8–1.0 μm in length and ∼200 nm in thickness. The Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanorod as cathode for Li-ion battery, delivers an impressive reversible capacity of 223 mAh.g−1 at 0.1C rate after 150 cycles and 161 mAh.g−1 at 1 C rate after 300 cycles. Rapid structural transition from layered to spinel-like phase at high temperature (55 °C) leads to gradual decay in discharge capacity upon cycling, whereas low Li-ion diffusivity, cell resistance, and high viscosity hampers the performance at low temperature (5 °C). Impedance spectroscopy along with (dis)charge differential plots corroborate that activation of Li 2 MnO 3 and Li-ion de(intercalation) into the MnO 2 phase is very facile at high temperature (55 °C), which leads to high specific capacity, high coulombic efficiency, and high-power capability. Herein, we demonstrate a facile solid-state template conversion strategy for the synthesis of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanorods, and was studied as cathode for Li ion batteries. The influence of testing temperature on the structural and electrochemical behavior of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanorods were analysed. Image 1 • Facile reactive template synthesis of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanorods using β-MnO 2 nanorods without any stabilizing or structure directing agents. • The Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 nanorods were 0.8–1.0 μm in length and 200 nm in width. • Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 delivered an impressive reversible capacity of 223 mAh.g−1 at 0.1C rate after 150 cycles and 161 mAh.g−1 at 1 C rate after 300 cycles. • The significant capacity decay observed at 55 °C is attributed mostly to layered to spinel-like structural changes. • The low capacity realized at 5 °C was related to high cell resistance and low Li+ diffusion kinetics. [ABSTRACT FROM AUTHOR]

In pursuit to find stable economic anode for aqueous lithium-ion batteries, tavorite structured LiFePO 4 OH 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. LiFePO 4 OH 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 LiFePO 4 | LiFePO 4 OH aqueous full cell has been fabricated having the first cycle capacity of 120 mAh g−1 (energy density ∼ 97 Wh kg−1). Tavorite LiFePO 4 OH forms an economic potential anode for aqueous Li-ion batteries. • Tavorite LiFePO 4 OH was implemented as anode material for aqueous Li-ion batteries. • It delivered 153 mAh g−1 discharge capacity at 1.0 mA cm−2 with good cyclability. • LiFePO 4 OH.| LiFePO 4 all phosphate full cell was fabricated. • A first discharge capacity of 120 mAh g−1 with 97 Wh kg−1 energy density was observed. [ABSTRACT FROM AUTHOR]

Solvothermal synthetic routes can provide energy-savvy platforms to fabricate battery anode materials involving relatively milder annealing steps vis-à-vis the conventional solid-state synthesis. These energy efficient routes in turn restrict aggressive grain growth to form nanoscale particles favouring efficient Li + diffusion. Here, we report an economic solution combustion synthesis of SrLi 2 Ti 6 O 14 anode involving nitrate-urea complexation with a short annealing duration of only 2 h (900 °C). Rietveld refinement confirms the phase purity of target product assuming an orthorhombic framework ( Cmca symmetry). It delivers reversible capacity of ∼125 mAh.g −1 at a rate of C/20 involving a 1.38 V Ti 4+ /Ti 3+ redox activity with excellent rate kinetics and cycling stability. Bond valence site energy (BVSE) calculations gauge SrLi 2 Ti 6 O 14 to be an anisotropic 3D Li + ion conductor with the highest ionic conductivity along the c direction. The electrochemical and diffusional pathways have been elucidated for combustion prepared SrLi 2 Ti 6 O 14 as an efficient and safe negative electrode candidate for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium sodium titanate insertion-type anode has been synthesized by classical solid-state (dry) and an alternate solution-assisted (wet) sonochemical synthesis routes. Successful synthesis of the target compound has been realized using simple Na- and Li-hydroxide salts along with titania. In contrast to the previous reports, these energy-savvy synthesis routes can yield the final product by calcination at 650–750 °C for limited duration of 1–10 h. Owing to the restricted calcination duration (dry route for 1–2 h and wet route for 1–5 h), they yield homogeneous nanoscale lithium sodium titanate particles. Sonochemical synthesis reduces the lithium sodium titanate particle size down to 80–100 nm vis-à-vis solid-state method delivering larger (200–500 nm) particles. Independent of the synthetic methods, the end products deliver reversible electrochemical performance with reversible capacity exceeding 80 mAh·g −1 acting as a 1.3 V anode for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (KIBs) can offer high-voltage performance and energy density similar to lithium-ion batteries with the added advantages of elemental abundance, materials economy, and efficient K+ intercalation due to smaller radius of solvated ions. This nascent field offers ample room to exploit open framework polyanionic compounds as efficient cathode materials. Due to similar ionic size, Na-based compounds can be employed as suitable cathodes for KIBs. In this work, iron-based mixed phosphate Na 4 Fe 3 (PO 4) 2 P 2 O 7 is demonstrated as a robust 3.0 V cathode for potassium-ion batteries. The in-situ carbon coated nanoscale Na 4 Fe 3 (PO 4) 2 P 2 O 7 cathode delivers a discharge capacity of ~120 mAh g−1 (i.e., 94% of its theoretical capacity) with excellent capacity retention and rate kinetics. With its three-dimensional open framework having multiple alkali sites, Na 4-x Fe 3 (PO 4) 2 P 2 O 7 undergoes a solid-solution Fe3+/Fe2+ redox mechanism acting as an efficient host for K+ (de)insertion. It forms the best Fe-based phospho-polyanionic cathode for potassium-ion batteries. A full cell comprising Na 4-x Fe 3 (PO 4) 2 P 2 O 7 cathode and graphite anode demonstrates the potential future application in KIBs. It marks the first demonstration of Na-based mixed polyanionic phosphates as insertion hosts for KIBs, which can be extended to various polyanionic insertion materials. Image 1 • Na-based mixed polyanion as robust intercalation host for K+-ions. • Reversible K+-ion intercalation in NASICON-type NaFe 3 (PO 4) 2 P 2 O 7 was demonstrated. • In-situ carbon coated Na 4 Fe 3 (PO 4) 2 P 2 O 7 delivered a capacity of ~118 mAh g−1 (~3e−). • Presence of 3D K-ion intercalating pathways and multiple K-ion sites in the structure. • Demonstration of full cell KIBs with NaK 3 Fe 3 (PO 4) 2 P 2 O 7 cathode and graphite anode. [ABSTRACT FROM AUTHOR]