Progress on multiphase layered transition metal oxide cathodes of sodium ion batteries

As one of the most promising secondary batteries in large-scale energy storage, sodium ion batteries (SIBs) have attracted wide attention due to the abundant raw materials and low cost. Layered transition metal oxides are one kind of popular cathode material candidates because of its easy synthesis and large theoretical specific capacity. Yet, the most common P2 and O3 phases show distinct structural characteristics respectively. O3 phase can serve as a sodium reservoir, but it usually suffers from serious phase transition and sluggish kinetics. For the P2 phase, it allows the fast sodium ion migration in the bulk and the structure can maintain stable, but it is lack of sodium, showing a great negative effect on Coulombic efficiency in full cell. Thus, single phase structure almost cannot achieve satisfied comprehensive sodium storage performances. Under these circumstances, exploiting novel multiphase cathodes showing synergetic effect may give solution to these problems. In this review, we summarize the recent development of multiphase layered transition metal oxide cathodes of SIBs, analyze the mechanism and prospect the future potential research directions.     

Revisiting the capacity-fading mechanism of P2-type sodium layered oxide cathode materials during high-voltage cycling

P2-type sodium layered oxide cathode (Na_2/3Ni_1/3Mn_2/3O_2,P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversib...     

Inside the failure mechanism of tin oxide as anode for sodium ion batteries

Journal of Solid State Electrochemistry - The conversion-alloying compounds have been identified as promising anode materials for sodium ion batteries (SIBs). One of them, SnO2, with an enormous...     

Sodium ion conducting nanocomposite polymer electrolyte membrane for sodium ion batteries

Journal of Solid State Electrochemistry - The paper reports effect of dispersion of titanium dioxide (TiO2) nanofiller on the sodium ion conducting nanocomposite polymer electrolyte membranes...     

Comments on stabilizing layered manganese oxide electrodes for Li batteries

An electrochemical study of structurally-integrated xLi₂MnO₃•(1 −x)LiMn_0.5Ni_0.5O₂ ‘composite’ materials has been undertaken to investigate the stability of electrochemically-activated electrodes at the Li₂MnO₃-rich end of the Li₂MnO₃–LiMn_0.5Ni_0.5O₂ tie-line, i.e., for 0.7 ≤ x ≤ 0.95. Excellent performance was observed for x = 0.7 in lithium half-cells; comparable to activated electrodes that have significantly lower values of x and are traditionally the preferred materials of choice. Electrodes with higher manganese content (x ≥ 0.8) showed significantly reduced performance. Implications for stabilizing low-cost, manganese-rich, layered lithium-metal-oxide electrode materials are discussed.     

Defective layered Mn-based cathode materials with excellent performance via ion exchange for Li-ion batteries

Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency. The annealing temperature of the Na precursors was important to control the P3-P2 phase transition, which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange. The O3-Li_0.78[Li_0.25Fe_0.075Mn_0.675]Oδcathode made from a P3-type precursor calcined at 700...     

Phase engineering of Ni-Mn binary layered oxide cathodes for sodiumion batteries

Nickel-manganese binary layered oxides with high working potential and low cost are potential candidates for sodium-ion batteries,but their electrochemical properties are highly related to compositional diversity.Diverse composite materials with various phase structures of P3,P2/P3,P2,P2/O3,and P2/P3/O3 were synthesized by manipulating the sodium content and calcination conditions,leading to the construction of a synthetic phase diagram for Na_xNi_0.25Mn_0.75O_2...     

P2-type Na0.59Co0.20Mn0.77Mo0.03O2 cathode with excellent cycle stability for sodium-ion batteries

Journal of Solid State Electrochemistry - Layered P2-type Mn-based material is considered as one of the most promising cathode materials for sodium-ion batteries, but its unsatisfactory cyclic...     

Occurrence of anionic redox with absence of full oxidation to Ru5+ in high-energy P2-type layered oxide cathode

The anionic redox has been widely studied in layered-oxide-cathodes in attempts to achieve highenergy-density for Na-ion batteries(NIBs).It is known that an oxidation state of Mn⁴⁺ or Ru⁵⁺ is essential for the anionic reaction of O^2-/O^-to occur during Na⁺ de/intercalation.However,here,we report that the anionic redox can occur in Ru-based layered-oxide-cathodes before full oxidation of Ru⁴⁺/Ru⁵⁺.Combining studies using ...     

Combustion-synthesized sodium manganese (cobalt) oxides as cathodes for sodium ion batteries

We report on the electrochemical properties of layered manganese oxides, with and without cobalt substituents, as cathodes in sodium ion batteries. We fabricated sub-micrometre-sized particles of Na_0.7MnO_2?+?z and Na_0.7Co_0.11Mn_0.89O_2?+?z via combustion synthesis. X-ray diffraction revealed the same layered hexagonal P2-type bronze structure with high crystallinity for both materials. Potentiostatic and galvanostatic charge/discharge cycles in the range 1.5–3.8 V vs. Na | Na⁺ were performed to identify potential-dependent phase transitions, capacity, and capacity retention. After charging to 3.8 V, both materials had an initial discharge capacity of 138 mA?h?g^?1 at a rate of 0.3 C. For the 20th cycle, those values reduced to 75 and 92 mA?h?g^?1 for Co-free and Co-doped samples, respectively. Our findings indicate that earlier works probably underestimated the potential of (doped) P2-type Na_0.7MnO_2?+?z as cathode material for sodium ion batteries in terms of capacity and cycle stability. Apart from doping, a simple optimization parameter seems to be the particle size of the active material.     

Tea-derived carbon materials as anode for high-performance sodium ion batteries

Sodium-ion batteries (SIB) have attracted widespread attention in large-scale energy storage fields owing to the abundant reserve in the earth and similar properties of sodium to lithium. Biomass-based carbon materials with low-cost, controllable structure, simple processing technology, and environmental friendliness tick almost all the right boxes as one of the promising anode materials for SIB. Herein, we present a simple novel strategy involving tea tomenta biomass-derived carbon anode with enhanced interlayer carbon distance (0.44 nm) and high performance, which is constructed by N,P co-doped hard carbon (Tea-1100-NP) derived from tea tomenta. The prepared Tea-1100-NP composite could deliver a high reversible capacity (326.1 mAh/g at 28 mA/g), high initial coulombic efficiency (ICE = 90% at 28 mA/g), stable cycle life (262.4 mAh/g at 280 mA/g for 100 cycles), and superior rate performance (224.5 mAh/g at 1400 mA/g). Experimental results show that the excellent electrochemical performance of Tea-1100-NP due to the high number of active N,P-containing groups, and disordered amorphous structures provide ample active sites and increase the conductivity, meanwhile, large amounts of microporous shorten the Na⁺ diffusion distance as well as quicken ion transport. This work provides a new type of N,P co-doped high-performance tomenta-derived carbon, which may also greatly promote the commercial application of SIB.     

Surface modified TiO2/reduced graphite oxide nanocomposite anodes for lithium ion batteries

Journal of Solid State Electrochemistry - Anatase TiO2 nanoparticles with an average crystallite size of ~ 20 nm are synthesized through a sol-gel method. A composite anode for...     

Advanced flexible electrode materials and structural designs for sodium ion batteries

With the spectacular rise of wearable and portable electronics, flexible power supplying systems with robust mechanical flexibility and high energy storage performance under various mechanical deformation conditions are imperative to be needed. Sodium ion batteries(SIBs) with sustainable natural abundance, low cost and superb properties similar to equivalent lithium ion batteries(LIBs), which have shown significant potentials as energy source for flexible electronic devices. In this review, the ...     

Dealloying-induced dual-scale nanoporous indium-antimony anode for sodium/potassium ion batteries

InSb alloy is a promising candidate for sodium/potassium ion batteries(SIBs/PIBs) but challenged with achieving high performance by dramatic volumetric changes. Herein, nanoporous(np)-InSb with dualscale phases(cubic/hexagonal(C/H)-InSb) was fabricated by chemical dealloying of ternary Mg-In-Sb precursor. Operando X-ray diffraction(XRD) and ex-situ characterizations well rationalize the dealloying/alloying mechanisms and the formation of dual-scale microstructures/phases. As an anode for SIB/PIB...     

Difficulties,strategies, and recent research and development of layered sodium transition metal oxide cathode materials for high-energy sodium-ion batteries

Energy-storage systems and their production have attracted significant interest for practical applications.Batteries are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devices(PEDs),etc.In recent decades,Lithium-ion batteries(LIBs) have been extensively utilized in largescale energy storage devices owing to their long cycle life and high energy density.However,the high cost and limited availability of Li are the two main obstacles for LIBs.In this reg...     

Recent developments on layered 3d-transtition metal oxide cathode materials for sodium-ion batteries

Sodium-ion batteries (SIBs) are now intensively developed as a cost-effective technology alternative to lithium-ion batteries (LIBs) for large-scale energy storage because of their various advantages such as huge abundance of sodium resources, highly safe and significantly low cost. Among many other cathode materials, layered 3d-transition metal oxides (LTMO-Na_xMO₂, x ≤ 1 and M = Co, Ni, Mn, Cr, Cu, Fe and V) have gained an enormous interest and attractive attention among researchers because of their low-cost, high energy density and ease of synthesis. In addition, LTMOs offer higher reversible capacities because of relatively lower molecular weights; however, complex phase transformations limit their cycling life. Based on the previous research, it was examined that the crystalline phase of LTMO highly influences the electrochemical performance of SIBs; therefore, this review mainly focuses on the latest advances of various crystalline phases such as P2-type, P3-type, O3-type and biphase/multiphase materials and its strength as well as future prospects and challenges.     

Synergetic stability enhancement with magnesium and calcium ion substitution for Ni/Mn-based P2-type sodium-ion battery cathodes

The conventional P2-type cathode material Na_0.67Ni_0.33Mn_0.67O₂ suffers from an irreversible P2–O2 phase transition and serious capacity fading during cycling. Here, we successfully carry out magnesium and calcium ion doping into the transition-metal layers (TM layers) and the alkali-metal layers (AM layers), respectively, of Na_0.67Ni_0.33Mn_0.67O₂. Both Mg and Ca doping can reduce O-type stacking in the high-voltage region, leading to enhanced cycling endurance, however, this is associated with a decrease in capacity. The results of density functional theory (DFT) studies reveal that the introduction of Mg²⁺ and Ca²⁺ make high-voltage reactions (oxygen redox and Ni⁴⁺/Ni³⁺ redox reactions) less accessible. Thanks to the synergetic effect of co-doping with Mg²⁺ and Ca²⁺ ions, the adverse effects on high-voltage reactions involving Ni–O bonding are limited, and the structural stability is further enhanced. The finally obtained P2-type Na_0.62Ca_0.025Ni_0.28Mg_0.05Mn_0.67O₂ exhibits a satisfactory initial energy density of 468.2 W h kg⁻¹ and good capacity retention of 83% after 100 cycles at 50 mA g⁻¹ within the voltage range of 2.2–4.35 V. This work deepens our understanding of the specific effects of Mg²⁺ and Ca²⁺ dopants and provides a stability-enhancing strategy utilizing abundant alkaline earth elements.

A synergetic effect involving Mg and Ca can reduce the adverse impact on redox reactions related to Ni–O bonding in Mg and Ca co-doped P2-Na_0.67Ni_0.33Mn_0.66O₂ material, leading to better overall properties than its singly-doped counterparts.     

Synthesis of MXene-supported layered MoS2 with enhanced electrochemical performance for Mg batteries

In this paper, the petal-like MoS₂/MXene composite has been successfully synthesized by one-step hydrothermal method. With the combination of few-layer MoS₂ nanosheets and the high conductive MXene substrate, the composite exhibits enhanced capacities and rate performance as cathode material of Mg batteries.     

Pampas grass-inspired FeOOH nanobelts as high performance anodes for sodium ion batteries

High-performance materials are the key to developing new alternative energy-storage systems[1-4].Sodium ion batteries(SIBs)are regarded as the promising large-scale electric energy storage owing to the high abundance and low cost of sodium resources[1,5-9].However,the sluggish kinetics of Na⁺caused by the large-sized Na⁺(1.02A)result in the lower energy density and unsatisfactory electrochemical properties[10-14].