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The interaction between Ir and La via O atoms as a bridge in a-IrOx/LaCO3OH boosts the acidic OER activity of a-IrOx.

Ten times heavy silver loading into a 3D scaffold via a strong Ag+–pN interaction between silver cations and argentophilic pyridinic nitrogen of melamine provides a strong lithiophilicity, largely improving lithium plating/stripping reversibility.

The IrO2/LiLa2IrO6 electrocatalyst achieves a win–win situation for both activity and stability towards the OER in acidic media, attributed to the in situ formed IrOx and strong interaction between IrOx and bulk LiLa2IrO6.

The discovery presented here revealed that oxidative potentials could facilitate redox reactions and/or oxygen evolution depending on the catalytic activity at the bismuth and ruthenium sites of Bi2Ru2O7 during electrocatalysis.

Very strong catalyst–support interaction was realized by supporting FePc with Ti3C2, encouraging biased electron transfer to Fe. 4e ORR activity was improved to suppress peroxide production and therefore to have ORR durability guaranteed.

The development of anode materials with high-rate capability is critical to high-power lithium batteries. T-Nb2O5 has been widely reported to exhibit pseudocapacitive behavior and fast lithium storage capability. However, the other polymorphs of Nb2O5 prepared at higher temperatures have the potential to achieve even higher specific capacity and tap density than T-Nb2O5, offering higher volumetric power and energy density. Here, micrometer-sized H-Nb2O5 with rich Wadsley planar defects (denoted as d-H-Nb2O5) is designed for fast lithium storage. The performance of H-Nb2O5 with local rearrangements of [NbO6] octahedra blocks surpasses that of T-Nb2O5 in terms of specific capacity, rate capability, and stability. A wide range variation in valence of niobium ions upon lithiation was observed for defective H-Nb2O5 via operando X-ray absorption spectroscopy. Operando extended X-ray absorption fine structure and ex-situ Raman spectroscopy reveals a large and reversible distortion of the structure in the two-phase region. Computation and ex-situ X-ray diffraction analysis reveals that the shear structure expands along major lithium diffusion pathways and contracts in the direction perpendicular to the shear plane. Planar defects relieve strain through perpendicular arrangements of blocks, minimizing volume change and enhancing structural stability. In addition, strong Li adsorption on planar defects enlarges intercalation capacity. Different from nanostructure engineering, our strategy to modify the planar defects in the bulk phase can effectively improve the intrinsic property. The findings in this work offer new insights into designing fast Li-ion storage materials in micrometer sizes through defect engineering, and the strategy is applicable to the material discovery for other energy-related applications.

We report a facile synthesis of an Ir surface-enriched IrCo alloy catalyst and its excellent activity which outperforms commercial Pt/C for the hydrogen evolution reaction (HER) in acidic media showing fast kinetics. The as-synthesized catalyst exhibits low overpotentials of merely 9 mV and 29.3 mV to afford current densities of 10 and 100 mA cm−2, respectively, a turnover frequency of 1.25 s−1, a low Tafel slope of 23.7 mV dec−1, and stability for 100 h at a high current density of 100 mA cm−2 in 0.5 M H2SO4 electrolyte. Experiments and density functional theory (DFT) calculations indicate that the enrichment of Ir atoms on the outer surface of IrCo alloys is responsible for the effectively optimized free energy of hydrogen adsorption, which boosts the kinetics and HER performance. Our finding provides an insight into the metal surface enrichment on alloy nanoparticles (NPs).

Designing highly efficient, stable and low-cost bifunctional electrocatalysts based on in situ microstructure evolution, especially achieving partial lattice dislocation on a highly crystalline texture, to catalyze the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is challenging. Herein, catalysts with the Ni3Fe alloy embedded in Ni3FeN ultrathin nanosheets (∼1 nm) were fabricated through thermal ammonolysis treatment of cation-vacant monolayered NiFe layered double hydroxides. The emergence of the Ni3Fe alloy during the annealing process unavoidably leads to strain output to adjacent microstructures in ultrathin nanosheets, contributing to the formation of lattice dislocations. Such lattice defects, combining the ultrathin 2D morphology and synergistic interfacial effect between Ni3FeN and Ni3Fe, endow the electrocatalyst (d-Ni3FeN/Ni3Fe) with excellent electrocatalytic performance for both the OER and HER in alkaline media, requiring overpotentials of 250 mV and 125 mV to drive a current density of 10 mA cm−2 in 1 M KOH, respectively. The water electrolyzer with d-Ni3FeN/Ni3Fe as the cathode and anode yields a current density of 10 mA cm−2 at a low cell voltage of 1.61 V, and exhibits excellent durability of over 90 h, outperforming the commercial IrO2‖Pt/C cell. The present study offers a new trial of lattice defect engineering to develop high-performance non-precious bifunctional electrocatalysts for overall water splitting.

Designing a conductive amorphous buffer layer between crystals (or lowering the crystallinity of one component) to minimize lattice-strain influence between a highly crystalline substance and nearby constituents, thus ensuring good electronic structure towards multiphase synergistic electro-catalysis, is of tremendous importance for the construction of high-performance catalysts. Here, combining solvothermal and calcination strategies, oxygen vacancy-abundant amorphous MoO3 and non-crystal MoO2 were implanted into amorphous N,P-doped carbon as MoOx/NPC to hybridize sub-10 nm crystalline ruthenium dots (Ru-MoOx/NPC). Amorphous NPC bridges MoOx with Ru crystal to avoid the direct contact of MoOx and Ru, thus weakening the lattice strain influence. The electrochemical measurement results show that Ru-MoOx/NPC exhibits excellent catalytical capacity towards hydrogen evolution reaction (HER), which only needs overpotentials of 30 mV and 27 mV to deliver the current density of 10 mA cm−2 in alkaline and acid electrolytes, respectively, outperforming numerous recent-reported catalysts. Such superior HER activity can be attributed to structural advantages of abundant oxygen deficiency, small-sized Ru dots, conductive amorphous NPC, and weakened lattice-strain for the maximum protection of key components. This study not only presents a well-defined nanostructure with high HER activity but also offers insight into the weakening of lattice-strain effects to support the catalytical property.

Designing efficient oxygen evolution reaction (OER) electrocatalysts based on single-atom catalysts is a highly promising option for cost-effective alkaline water electrolyzers. However, the instability of the OOH* intermediate and high energy barrier for the rate-determining step (RDS) (O* to OOH*) on the pure bimetallic-alloy represent serious challenges. Here, we report atomically dispersed Ru single-atoms on a cobalt–iron bimetallic-alloy encapsulated by graphitic carbon (RuSACoFe2/G) as an efficient and durable electrocatalyst for the alkaline OER. In-depth X-ray absorption spectroscopy (XAS) and aberration-corrected transmission electron microscopy (AC-TEM) along with theoretical calculations were employed to validate the isolated Ru sites in the surface-oxygen rich alloy. RuSACoFe2/G displays exceptional intrinsic activity, achieving a record low overpotential of only 180 mV at 10 mA cm−2 with superior durability in alkali media. Density functional theory (DFT) simulations revealed that the isolated Ru sites with pre-adsorbed surface oxygen species on a bimetallic-alloy efficiently stabilize the OOH* intermediate and significantly reduce the energy barrier for the RDS, boosting the intrinsic OER activity. Our integrated alkaline electrolyzer demands a low cell voltage of 1.48 V at 10 mA cm−2, suggesting that it has potential for use in practical applications.

Developing a highly efficient and cost-effective electrocatalyst for catalyzing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is fundamentally important for the practical application of the overall water splitting technique. Herein, a bifunctional electrocatalyst constituted by FexNiy and CeO2 nanoparticles supported on the N-doped nanocarbon (NC) is fabricated by a simple one-pot pyrolysis of the homogeneous mixture of Fe, Ni, Ce nitrates and melamine. The synergistic effect of each component in the FexNiy/CeO2/NC gives rise to outstanding electrocatalytic activities and stability toward the HER and OER. For hydrogen evolution, the FexNiy/CeO2/NC shows a smaller overpotential of 260 mV to achieve a current density of 50 mA cm−2 in a 1 M KOH electrolyte. More significantly, a small overpotential of 240 mV for FexNiy/CeO2/NC affords an oxygen evolution current density of 10 mA cm−2, far lower than that of the benchmark IrO2. The practicability and electrocatalytic activity of the prepared FexNiy/CeO2/NC under practical operation conditions are also investigated. In particular, the FexNiy/CeO2/NC-based overall water splitting cell only needs a cell voltage of 1.70 V to output 10 mA cm−2 in alkaline electrolytes, comparable to that of the IrO2∥Pt/C cell. The present study may pioneer a new avenue for developing novel bifunctional electrocatalysts with high-performance and low cost for water splitting.

Developing low-cost and highly efficient electrocatalysts for overall water splitting is of far-reaching significance for new energy conversion. Herein, dual-cation Fe, Al-co-doped NiSe2 nanoparticles on reduced graphene oxide (Fe, Al-NiSe2/rGO) were prepared as a bifunctional electrocatalyst for overall water splitting. The dual-cation doping can induce a stronger electronic interaction between the foreign atoms and host catalyst, for optimizing the adsorption energy of reaction intermediates. Meanwhile, the leaching out of Al from the crystal structure of the target product during the alkaline wash creates more defects and increases the active site exposure. As a result, the Fe, Al-NiSe2/rGO catalyst exhibits excellent catalytic activities for both the OER and HER with an overpotential of 272 mV @η10 for the OER in 1.0 M KOH and 197 mV @η10 for the HER in 0.5 M H2SO4, respectively. A two-electrode electrolyzer using Fe, Al-NiSe2/rGO as the anode and cathode shows a low voltage of 1.70 V at the current density of 10 mA cm−2. This study emphasizes the synergistic contribution of the dual-cation co-doping effect and more defects created by Al leaching to boost the performance of water splitting.

The development of highly efficient and inexpensive catalysts is still a tremendous challenge for the electrocatalytic nitrogen reduction reaction (NRR), which is a promising alternative to high-temperature and high-pressure industrial technologies for the synthesis of NH3. Herein, we report a facile and large scale strategy exploiting a porous non-precious bimetallic oxide of NiWO4 for the NRR under ambient conditions. Benefiting from the above-mentioned merits, the designed electrocatalyst achieved outstanding catalytic activities in both 0.1 M HCl (NH3 yield: (40.05 ± 1.45) μg h−1 mg−1cat., Faraday efficiency (FE): (19.32 ± 0.68)% at −0.3 V) and 0.1 Na2SO4 (NH3 yield: (23.14 ± 1.75) μg h−1 mg−1cat., Farady efficiency: (10.18 ± 0.62)% at −0.3 V), and these efficiencies are superior to most of the reported non-precious metals for the NRR. Furthermore, the prepared catalyst presented excellent stability in both acidic and neutral media for up to 20 h. This work opens a constructive avenue for optimizing the catalytic performance of metal oxides and other transition metal-based catalysts for NRRs.

The structure–property relationship in transition metal oxides is of crucial importance in designing and synthesizing economically feasible high-performance electrocatalysts. Since cation substitution allows to finely tailor the atomic arrangement, structural distortion, and electrocatalytic performance of transition metal oxides, a relationship between local structural order and electrocatalytic activity in crystalline manganese oxide can be systematically investigated by in situ X-ray absorption, electron paramagnetic resonance, and electrochemical impedance spectroscopic analyses for unsubstituted and Fe-substituted α-Mn1−xFexO2 during the oxygen evolution reaction (OER). The substitution of Mn with Fe is quite effective in improving the OER activity of α-MnO2 to reach a small overpotential of 0.40 V at 10 mA cm−2. Under OER conditions, the Fe substitution improves the local structural order of MnO6 octahedra in the α-MnO2 lattice, thus leading to a significant enhancement of charge transport kinetics. Since the Fe substitution induces only a limited alteration of the electronic structure and the substituted Fe ion itself shows only a negligible contribution to the OER activity, the excellent OER functionality of Fe-substituted α-Mn1−xFexO2 is attributable mainly to the improvement of local structural ordering upon Fe substitution. The present study underscores the crucial role of local structural order in optimizing the electrocatalytic functionality of crystalline transition metal oxides.

Metal oxide based solar thermal water splitting is a promising approach for using solar energy to produce H2 and O2. The normal protocol employed for this process involves thermal reduction of a metal oxide (MOx) at around 1500 °C to produce the reduced form of the metal oxide (MOx−δ) and O2. This step is followed by steam treatment of MOx−δ at around 1000 °C to yield MOx and H2. Owing to the need to use high temperatures, the traditional approach has several important drawbacks. In a study designed to improve this process, we found that Cu-loaded TiO2 (Cu/TiO2) effectively expels O2 upon irradiation with AM 1.5 1 Sun solar simulated light and that treatment of the reduced form of the reduction product Cu/TiO2−δ with steam at 140 °C generates H2. This new approach, termed as solar photochemical–thermal water splitting, has the potential to become an important method for converting solar energy into chemical energy.

Oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) electrocatalysts including carbon-, non-precious metal-, metal alloy-, metal oxide-, and carbide/nitride-based materials are of great importance for energy conversion and storage technologies. Among them, metal oxides (e.g., perovskite and pyrochlore) are known to be promising candidates as electrocatalysts. Nevertheless, the intrinsic catalytic activities of pyrochlore oxides are still poorly understood because of the formation of undesirable phases derived from the synthesis processes. Herein, we present highly pure single crystalline pyrochlore nanoparticles with metallic conduction (Pb2Ru2O6.5) as an efficient bi-functional oxygen electrocatalyst. Notably, it has been experimentally shown that the covalency of Ru–O bonds affects the ORR and OER activities by comparing the X-ray absorption near edge structure (XANES) spectra of the metallic Pb2Ru2O6.5 and insulating Sm2Ru2O7 for the first time. Moreover, we followed the interatomic distance changes of Ru–O bonds using in situ X-ray absorption spectroscopy (XAS) to investigate the structural stabilities of the pyrochlore catalysts during electrocatalysis. The highly efficient metallic Pb2Ru2O6.5 exhibited outstanding bi-functional catalytic activities and stabilities for both ORR and OER in aqueous Zn–air batteries.

The need to find sodium ion battery (SIB) cathodes with high voltage, capacity and improved cycle life has stimulated research on sodium containing layered transition metal oxides. With this perspective, the electrochemical properties of highly ordered, honeycomb layered Na3Ni2BiO6 with a monoclinic superstructure are explored as a cathode material in SIBs. It has been demonstrated that Na3Ni2BiO6 delivers a discharge capacity of 106 mA h g−1, having high voltage plateaus at 3.50 and 3.25 V, with marginal capacity fading after 50 cycles. Operando X-ray diffraction studies during charging/discharging reveal two reversible two-phase transition mechanisms (initial O3 phase → P3 intermediate phase → O1 final phase) during sodium extraction. Ex situ X-ray absorption spectroscopy reveals the charge compensation mechanism for the reversible Ni3+/Ni2+ as an active redox couple while Bi5+ being inactive during cycling. Extended X-ray absorption fine structure analysis shows highly reversible local structural changes around both Ni and Bi atoms occurring during electrochemical cycling. In addition, unique local structure changes especially around Ni atoms due to the honeycomb ordering and size mismatch between Ni2+ and Bi5+ ions are revealed by EXAFS analysis during charging and discharging, which is quite different from the local structure changes in regular layer structured NaMO2 (M = transition metals) cathode materials. The present results suggest that honeycomb layered metal oxides with the general formula, Na3M(II)2M(V)O6, can be considered as candidates for high voltage and long life cathode materials for SIBs.

Highly efficient bifunctional oxygen electrocatalysts are indispensable for the development of highly efficient regenerative fuel cells and rechargeable metal-air batteries, which could power future electric vehicles. Although perovskite oxides are known to have high intrinsic activity, large particle sizes rendered from traditional synthesis routes limit their practical use due to low mass activity. We report the synthesis of nano-sized perovskite particles with a nominal composition of Lax(Ba[subscript 0.5]Sr[subscript 0.5])[subscript 1−x]Co[subscript 0.8]Fe[subscript 0.2]O[subscript 3−δ] (BSCF), where lanthanum concentration and calcination temperature were controlled to influence oxide defect chemistry and particle growth. This approach produced bifunctional perovskite electrocatalysts ∼50 nm in size with supreme activity and stability for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalysts preferentially reduced oxygen to water (, MIT & Masdar Institute Cooperative Program (02/MI/MIT/CP/11/07633/GEN/G/00), MIT Skoltech Initiative

The high cost of Pt-based membrane electrode assemblies (MEAs) is a critical hurdle for the commercialization of polymer electrolyte fuel cells (PEFCs). Recently, non-precious metal-based catalysts (NPMCs) have demonstrated much enhanced activity but their oxygen reduction reaction (ORR) activity is still inferior to that of Pt-based catalysts resulting in a much thicker electrode in the MEA. For the reduction of mass transport and ohmic overpotential we adopted a new concept of catalyst that combines an ultra-low amount of Pt nanoclusters with metal–nitrogen (M–Nx) doped ordered mesoporous porphyrinic carbon (FeCo–OMPC(L)). The 5 wt% Pt/FeCo–OMPC(L) showed a 2-fold enhancement in activities compared to a higher loading of Pt. Our experimental results supported by first-principles calculations indicate that a trace amount of Pt nanoclusters on FeCo–OMPC(L) significantly enhances the ORR activity due to their electronic effect as well as geometric effect from the reduced active sites. In terms of fuel cell commercialization, this class of catalysts is a promising candidate due to the limited use of Pt in the MEA.

The bacterial respiration process enables the facile and morphologically-selective preparation of nanomaterials, along with the removal of environmentally toxic elements. Bacteria-driven metallic tellurium Te(0) nanorods formed extra- and intracellularly by Shewanella oneidensis MR-1, consisting of a helically-twisted atomic-wire bundle structure, exhibited distinct Li-ion uptake properties after direct or glucose-assisted surface-carbonization of bacterial cells. By synchrotron-based in situ structural characterization during cycling, it was demonstrated that the carbonized polycrystalline Te materials experience phase transition to Li2Te through simple Li-ion diffusion and charge compensation by the anionic redox reaction of metallic Te to polyanionic telluride (Ten2−). On the other hand, the carbonized amorphous Te materials show simple Li-ion accumulation around Te element with only the anionic redox reaction. The gradual generation of electrostatic interactions between Li+ and Ten2− ion pairs promotes host lattice stabilization, unlike in other metallic anode systems with volume expansion. We report that the unusual anionic redox chemistry of Te with its structural flexibility drives the reversible Li-ion uptake without any critical structural deterioration, highlighting the potential of tellurium as a new energy conversion and storage material.

A graphene-attached VS4 composite prepared by a simple hydrothermal method is studied in terms of its lithium reaction mechanism and high rate capability. The nanocomposite exhibits a good cycling stability and an impressive high-rate capability for lithium storage, delivering a comparable capacity of 630 and 314 mA h g−1, even at high rates of 10 and 20 C (=10 and 20 A g−1, or 10 and 20 mA cm−2), respectively. In addition, full-cell (LiMn2O4/VS4–graphene) test results also exhibited a good capacity retention. The mechanism of Li storage is systematically studied and a conversion reaction with an irreversible phase change during the initial discharge–charge process is proposed.

Nanocrystalline Li[NixLi(1−2x)/3Mn(2−x)/3]O2 powders were prepared by a simple combustion method and investigated using X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), particle size analysis (PSA), and galvanostatic charge/discharge cycling. According to the XRD analysis, single-phase compounds with a layered structure were obtained for powders with 0 ≤ x ≤ 0.25, while mixtures were obtained for powders with 0.30 ≤ x ≤ 0.50. Rietveld analysis revealed that single-phase Li[NixLi(1−2x)/3Mn(2−x)/3]O2 is basically a layered rock-salt structure in which a small amount of Ni occupies the 3a sites. The initial discharge capacity of a Li/Li[NixLi(1−2x)/3Mn(2−x)/3]O2 cell with x = 0.20 was about 288 mA h g−1, corresponding to about 91% of the theoretical value, when it was cycled in the voltage range of 4.8–2.0 V with a specific current of 20 mA g−1 at 30 °C. As far as we know, charge/discharge cycling on an Li/Li[Ni0.20Li0.20Mn0.60]O2 cell gives the highest discharge capacity of 288 mA h g−1 among the LiMO2-based (M = Co, Ni, and Mn) cathode materials. A very promising factor for high-rate capability applications was an excellent rate capability in continuous cycling at specific currents ranging from 20 mA g−1 to 900 mA g−1, due to the nanocrystalline particle size of 80–200 nm. The origin of the 4.5 V plateau was investigated by means of weight loss measurement and XAS for the charged/discharged electrodes. The weight loss measurement for the charged electrodes gave indirect evidence that the 4.5 V plateau did not originate from the ejection of oxygen. In XAS, the Mn oxidation state of 4+ did not change during the charge/discharge process, and surprisingly the Ni did not further oxidize beyond about 3+.

The Li[Li0.15Ni0.275−xMgxMn0.575]O2 (x = 0, 0.02, and 0.04) powders have been synthesized using a sol–gel method. The layered structure of the materials is stabilized by a small amount of Mg substitution for Ni. The structural stability and cycling behavior are improved by an increase in the Mg content. The XAS measurements show that charge compensation by delithiation could be achieved by the oxidation of the oxygen ion as well as by the oxidation of Ni2+ to Ni3+, while maintaining the Mn atoms in the 4+ oxidation state.

Li[Ni0.25Li0.15Mn0.6]O2 nanowires having an aspect ratio of several hundreds and with a diameter of about 30 nm were synthesized at a pH of 2 during a hydrothermal process at 200 degrees C for 5 h without using a template. The nanowires exhibited a first discharge capacity of 311 mA h g(-1) and a rate capability of 95% at 4C (=1200 mA g(-1)).

Since one of the main drawbacks of Li4Ti5O12 as a negative-electrode material is its low electronic conductivity, several researchers have attempted to improve the conductivity by narrowing the band gap through transition-metal doping. Herein, we report another, more significant effect of doping in addition to the band gap narrowing, namely, an anomalous decrease in the structural disorder in Li4Ti5O12 upon Cr3+-ion doping. Although it is generally recognized that doping with heterogeneous elements increases the structural disorder, the Cr3+-ion doping in Li4Ti5O12 demonstrated an unexpected structural phenomenon. From the results of various structural analyses using a synchrotron beam, such anomalous structural changes were revealed to originate from charge redistribution at nearby Ti4+ ions. Finally, the capacity was markedly enhanced, especially at high C-rates (125 mA h g−1 for 10C charge/10C discharge, 145 mA h g−1 for 1C charge/50C discharge) because of both the band gap narrowing and the increased ionic diffusivity due to the decreased structural disorder, but was decreased instead for too-high doping levels.

Provided is a method for preparing a chalcogenic hybrid nanostructure including: (a) adding a chalcogenic nanostructure, an electron donor and an electron acceptor to a medium containing metal-reducing bacteria to prepare a reaction mixture, the electron acceptor including a chalcogen element; and (b) performing a metal reduction reaction using the prepared reaction mixture to prepare a chalcogenic hybrid nanostructure with the chalcogen element of the electron acceptor incorporated. The present disclosure provides a new method allowing preparation of a chalcogenic hybrid nanostructure comprising three or more components using metal-reducing bacteria. The disclosure allows preparation of a nanostructure in a more economical and eco-friendly manner. The disclosure also allows control of morphological, physical/chemical and electrical properties of the prepared nanostructure. In addition, the present disclosure provides a nanomaterial that can be useful in nanoelectronic and optoelectronic devices.

Highly air stable Al2O3-coated Li2NiO2 cathode additive is prepared by coating with Al iso-propoxide on Li2NiO2, obtained from firing of a physical mixture of pure Li2O and NiO at 600 °C for 10h under N2 atmosphere. An as-prepared coated cathode has first charge and discharge capacities of 420 mAh/g and 310 mAh/g, respectively, between 4.3V and 1.5V showing an irreversible capacity ratio of 26%. However, when the discharge cut-off voltage increases to 2.75V (2.85V vs. graphite), its discharge capacity decreases to 120 mAh/g, which corresponds to an irreversible capacity ratio of 71%. Owing to such a high irreversible capacity, it can effectively compensate for the irreversible capacity of the Li-ion cell using LiCoO2 and natural graphite as cathode and anode materials, respectively, in spite of only 4wt% addition to the LiCoO2 cathode. In addition, the additive prevents the 12V overcharge, thereby preventing the explosion of the cell. We believe that Li2NiO2decomposition consumes the surplus current during the overcharging to 12V, and therefore the voltage is not increased until the complete decomposition of the Li2NiO2.

Monoclinic ZnP2 particles were synthesized by vacuum annealing of a mixture consisting of P and Zn powders at 1000 °C. In contrast to a tetragonal Zn3P2 phase, a very large plateau corresponding to 1000 mAh g−1 at ∼0.45 V was developed, and out to 545 mAh g−1, only topotactic lithium ion intercalation into the molecule pores was observed. The excess Li ion uptake beyond simple Li intercalation (>545 mAh g−1) into molecular pores can break a chemical bond between Zn and the phosphorus atoms. During discharge, the formation of the LinP clusters (LiP5 and LiP) and Zn, LiZnP phases were dominant as a result of the local structural distortion around the ZnP4 tetrahedral site. During charge, Zn and LiP5 phases transformed into ZnP2 and LiP phases. However, decomposition reactions of the LiP and ZnP2 phases with the electrolyte led to the capacity fade of the cell.