Poor Intrinsic Electronic Conductivity Research Articles

Facile Synthesis of SnNb2 O6 @C Composite with Ultrathin Carbon Layer as Anode Materials for High-Performance Sodium-Ion Batteries.

Niobium-based oxides have attracted a lot of attention as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, excellent rate capability and exceptional safety. However, their poor intrinsic electronic conductivity and sluggish sodium ions diffusion kinetics severely hinder their practical applicability. Here, SnNb2 O6 @C was successfully prepared by a simple solid-state reaction technique coupled with carbon coating. HRTEM images show that the SnNb2 O6 @C particles are covered with uniformly ultrathin amorphous carbon layer of about 1.8 nm, thus improving the electronic conductivity and diffusion coefficient of sodium ions. As anode for SIBs, the as-obtained SnNb2 O6 @C material exhibits excellent specific capacity (369 mAh g-1 at a current density of 50 mA g-1 ) and remarkable rate performance (177 mAh g-1 at 1000 mA g-1 ), which indicates its good prospect in practical application.

Enhanced electrochemical performances of FeS/PC composites as anode materials for lithium-ion batteries

• FeS@PC anode material where FeS nanoparticles embedded in the porous carbon was synthesized by two-step in-situ immersion/calcination method. • The electrochemical properties of the FeS@PC anode material are evaluated. • The material achieves a high initial discharge capacity of 1397.3 mAh/g and reversible capacities of 592 mAh/g at a current density of 0.1 C after 65 cycles. Due to the various micro/nanostructures and high theoretical specific capacities, transition-metal compounds are attractive anodes for next-generation lithium-ion batteries (LIBs). The practical use of transition metal oxides as anode materials for commercial LIBs is hindered by their limited long-term stability and poor intrinsic electronic conductivity. Here we present the realization of embedded ferrous sulfide (FeS) nanoparticles in the porous carbon (PC) by a two-step in-situ immersion/calcination method. The electrochemical properties are evaluated by cyclic voltammogram, electrochemical impedance and discharge-charge galvanostatic (constant current) tests. By optimizing the reaction conditions, the LIBs achieves a high initial discharge capacity of 1397.3 mAh/g and reversible capacities of 592 mAh/g at a current density of 0.1 C after 65 cycles. With these promising results, the FeS/PC composites exhibit considerable potential applications for lithium-ion batteries.

One-step multiple structure modulations on sodium vanadyl phosphate@carbon towards ultra-stable high rate sodium storage

• A template-assisted sol–gel strategy is proposed for multi-structure engineering of NVP@C cathode material. • Simultaneous realizations of pore constructing, nanosizing and carbon compositing can be achieved in one step. • Pore structure of NVP@C can be tuned by adjusting the diameter of PS nanospheres. • A novel mesoporous-macroporous structure can be realized due to the demulsification of PS emulsion. • The mesoporous-macroporous NVP@C exhibits extraordinary rate capability and cycling stability at high rate. Na 3 V 2 (PO 4 ) 3 (NVP) is recognized as a promising sodium ion battery (SIB) cathode material due to its high working potential and robust three-dimensional framework. However, the poor intrinsic electronic conductivity and huge volume change during sodium ion insertion/desertion process hinder its further applications, which makes its structure modulations highly desirable. Herein, a facile template-assisted sol–gel strategy is developed to realize multiple structure modulations of NVP@C in one-step. With citric acid as chelating agent and polystyrene (PS) nanospheres as template, the realization of nanosizing NVP particles, hybridizing NVP particle with carbon material and constructing pore structure on NVP@C can be facially achieved. More importantly, the pore structure can be tuned by the diameter of used PS nanospheres. When the diameter of PS nanospheres is down to 70 nm, the corresponding 70-PS NVP possesses a hierarchically mesoporous-macroporous structure due to the demulsification effect, which can shorten the ion diffusion pathway, increase the contact surface area between the electrolyte and active material, improve the diffusion kinetics and buffer the volume change. Benefiting from the above superiority, the sample exhibits an extraordinary rate capability and a prominent cycling stability at high rate (104 mAh g −1 after 5000 cycles at 50C), which surpass most of the recently reported SIB cathode materials. This work opens a facile revenue for boosting the electrochemical performance of electrode materials through characteristic pore construction, nanosizing and integration with carbonaceous materials.

NASICON-structured Na3MnTi(PO4)2.83F0.5 cathode with high energy density and rate performance for sodium-ion batteries

NASICON-structured materials with high ionic conductivity, robust structure, and high operation potential have aroused extensive attentions as cathode for sodium-ion batteries (SIBs). However, the poor intrinsic electronic conductivity and low specific capacity are crucial obstacles for practical application of NASICON materials. Herein, a new NASICON-structured Na3MnTi(PO4)2.83F0.5 (NMTPF-0.5) with the hierarchical and porous structure is synthesized by a simple sol–gel method. The Rietveld refinements and Inductively Coupled Plasma (ICP) chemical analysis confirms the NASICON structure of NMTPF-0.5. The unique structural design significantly enhances rate performance. Meanwhile, the introduction of F- stimulates electrochemical activities of Mn, and stabilizes crystal structure compared with traditional Na3MnTi(PO4)3. Consequently, the NMTPF-0.5 achieves the high energy density of 511 Wh kg−1 at 0.1C, an outstanding rate performance (364 Wh kg−1 at 10C), and the desirable cycling stabilities exceeding 500 cycles at 10C. The ex-situ XRD reveals the insertion/extraction of Na+ through the reversible solid-solution mechanism. Moreover, we statistically analyze how the electrochemical properties and microstructure affected by various F- substitution amounts. This study explored a novel strategy for designing high capacity and high power-density cathode materials for SIBs via the microstructure and crystal structure optimization.

In-situ structural evolution analysis of Zr-doped Na3V2(PO4)2F3 coated by N-doped carbon layer as high-performance cathode for sodium-ion batteries

With great superiorities in energy density, rate capability and structural stability, Na3V2(PO4)2F3 (NVPF) has attracted much attentions as cathode of sodium ion battery (SIB), but it also faces challenges on its poor intrinsic electronic conductivity and the controversial de/sodiation mechanism. Herein, a series of Zr-doped NVPF coated by N-doped carbon layer (~5 nm in thickness, homogenously) materials are fabricated by a sol–gel method, and the optimized heteroatom-doping amounts of Zr and N doping improve intrinsic properties on enlarging lattice distance and enhancing electronic conductivity, respectively. Specifically, among all samples of Na3V2−xZrx(PO4)2F3/NC (NVPF-Zr-x/NC, x = 0, 0.01, 0.02, 0.05, and 0.1), the optimized electrode of NVPF-Zr-0.02/NC delivers high reversible capacities (119.2 mAh g−1 at 0.5 C), superior rate capability (98.1 mA h g−1 at 20 C) and excellent cycling performance. The structural evolution of NVPF-Zr-0.02/NC electrode, in-situ monitored by X-ray diffractometer, follows a step-wise Na-extraction/intercalation mechanism with reversible multi-phase changes, not just a solid-solution-reaction one. Full cells of NVPF-Zr-0.02/NC//hard carbon demonstrate high capacity (99.8 mA h g−1 at 0.5 C), high out-put voltage (3.5 V) and good cycling stability. This work is favorable to accelerate the development of high-performance cathode materials and explore possible redox reaction mechanisms of SIBs.

Porous yolk-shell structured Na3(VO)2(PO4)2F microspheres with enhanced Na-ion storage properties

Na3(VO)2(PO4)2F (NVPOF) has been considered as one potential candidate for sodium-ion batteries because of its high operating voltage and theoretical capacity. However, the poor intrinsic electronic conductivity significantly restricts its widespread application. In response to this drawback, we adopt the optimization strategy of tuning the morphology and structure to boost the electrical conductivity and mitigate the capacity fading. In this paper, NVPOF microspheres with unique porous yolk-shell structure were fabricated via a facile one-step solvothermal method for the first time. By monitoring the morphological evolution with time-dependent experiments, the self-sacrifice and Ostwald ripening mechanism from rough spheres to yolk-shell structure was revealed. Benefited from the favorable interwoven nanosheets shell, inner cavity and porous core structure, the resulting NVPOF electrode exhibits superior rate capability of 63 mA h g−1 at 20 C as well as outstanding long-cycling performance with the capacity retention up to 92.1% over 1000 cycles at 5 C.

SiOx@C composites obtained by facile synthesis as anodes for lithium- and potassium-ion batteries with excellent electrochemical performance

Low silicon oxide (SiO) is a promising anode material for lithium and potassium ion batteries due to its high theoretical capacity (~2400 mAh g−1) and good cycle performance. However, volume effects and poor intrinsic electronic conductivity during cycling limit its practical application. To meet this challenge, we synthesized SiOx@C (SC) anodes with various carbon contents by ball milling and high-temperature carbonization. The graphite/asphalt coating reduces the volume expansion of SiO and reduces the mechanical stress. When used as a lithium ion battery (LIB) electrode, the SC-2 material retained a lithium storage capacity of 729.5 mAh g−1 after 200 cycles at a current density of 200 mA g−1. In addition, when used as a potassium ion battery (KIB) electrode, the SC-2 material provides a high capacity with a discharge capacity of 107.0 mAh g−1 after 400 cycles at 200 mAh g−1 and excellent cycle life (after 2000 cycles at 500 mA g−1, the capacity 80.8 mAh g−1 was retained). The potassium storage mechanism of the SC electrode was analyzed by the simple ex-situ XRD technique. These results show that SC anodes are promising for application as anode materials for LIBs and KIBs.

Improvement of electrochemical performance of the Li9V3(P2O7)3(PO4)2 cathode material by aliovalent Mo4+ doping

Attributed to the realization of the multielectron transfers, with a stable 3D framework, Li9V3 (P2O7)3(PO4)2 is considered an excellent cathode material, which can reversibly extract/insert nearly 5 mol Li. However, the poor intrinsic electronic conductivity and the low lithium diffusion coefficient limited its practical electrochemical ability. Considering the poor intrinsic electronic conductivity of the pristine Li9V3(P2O7)3(PO4)2 compound, the introduction of one extra electron by replacing V3+ with aliovalent Mo4+ ions increases the concentration of the electronic charge carriers from Li9V3(P2O7)3(PO4)2 and thus improves the electronic conductivity. At the same time, the larger ionic radius of Mo4+ leads to the increasement of the cell volume of the Li9V3(P2O7)3(PO4)2 sample and thus facilitates Li+ transport into the structure. As a result, the electrochemical performances of the Li9V3(P2O7)3(PO4)2 were improved obviously by a small amount of Mo. Especially for the Li9V3-xMox(P2O7)3(PO4)2 (x = 0.02) sample, the electrode present the highest specific capacity herein and an excellent rate performance which is a promising cathode for lithium ion battery application.

Mo-modified P/C composite as anode for high-performance sodium ion batteries

Red P is one of the most prospective anode material for sodium ion battery because of its highest theoretical capacity of 2596 mAh g−1 and satisfactory potentials for sodium ions insertion and extraction. However, the large volume expansion during cycles and poor intrinsic electronic conductivity limit the electrical performance practical application of red P. Herein, Mo-modified P/C (PMoC) composite has been prepared through a simple mechanical milling using low-cost anthracite as carbon sources to increase the electrical conductivity and adapt to the volume variation. The addition of Mo plays a crucial role in enhancing electronic conductivity and structural stability of PMoC composite during cycles. The formation of MoP2 facilitates the intimate contact of red P and Mo, providing the superior ionic diffusion and electron conducting pathways between the particles. The electrode of PMoC exhibits high reversible capacity, excellent cycling and rate performance as anode for sodium ion battery. At 0.1 and 0.5 A g−1, the PMoC electrode displays high reversible capacities of 763 and 705 mAh g−1 after 60 and 100 cycles, respectively. Due to the superior electrochemical performance, low cost and simple preparation, the PMoC composite is a prospective negative electrode material for high-performance sodium ion battery.

Realizing Reversible Conversion‐Alloying of Sb(V) in Polyantimonic Acid for Fast and Durable Lithium‐ and Potassium‐Ion Storage

AbstractFinding suitable electrode materials for alkali‐metal‐ion storage is vital to the next‐generation energy‐storage technologies. Polyantimonic acid (PAA, H2Sb2O6 · nH2O), having pentavalent antimony species and an interconnected tunnel‐like pyrochlore crystal framework, is a promising high‐capacity energy‐storage material. Fabricating electrochemically reversible PAA electrode materials for alkali‐metal‐ion storage is a challenge and has never been reported due to the extremely poor intrinsic electronic conductivity of PAA associated with the highest oxidation state Sb(V). Combining nanostructure engineering with a conductive‐network construction strategy, here is reported a facile one‐pot synthesis protocol for crafting uniform internal‐void‐containing PAA nano‐octahedra in a composite with nitrogen‐doped reduced graphene oxide nanosheets (PAA⊂N‐RGO), and for the first time, realizing the reversible storage of both Li+ and K+ ions in PAA⊂N‐RGO. Such an architecture, as validated by theoretical calculations and ex/in situ experiments, not only fully takes advantage of the large‐sized tunnel transport pathways (0.37 nm2) of PAA for fast solid‐phase ionic diffusion but also leads to exponentially increased electrical conductivity (3.3 S cm−1 in PAA⊂N‐RGO vs 4.8 × 10−10 S cm−1 in bare‐PAA) and yields an inside‐out buffer function for accommodating volume expansion. Compared to electrochemically irreversible bare‐PAA, PAA⊂N‐RGO manifests reversible conversion‐alloying of Sb(V) toward fast and durable Li+‐ and K+‐ion storage.

Influences of co-sputtered carbon on the electrochemical performance of SiO/C thin film anodes for lithium-ion batteries

Silicon suboxide (SiOx) is a promising anode material for lithium-ion batteries due to its high theoretical capacity (∼2400 mA h g-1) and good cycle performance. However, the volume effect during cycling and the poor intrinsic electronic conductivity restrict its practical application. Since SiO thin films with carbon additive are able to cope with these limitations, we have synthesized SiO/C thin film anodes containing various carbon contents by magnetron co-sputtering. Among the as-deposited electrodes, SiO/C-80 with a thickness of 1.15 μm showed superior electrochemical performance with an initial coulombic efficiency of ∼72%, a maximum reversible specific capacity of 1223 mA h g-1 and a capacity retention of 82.0% ± 0.5% after 750 cycles at a current density of 1 A g-1. The co-sputtered carbon is uniformly dispersed inside the film, which enhances the electronic conductivity and enables higher reversible capacity during the initial cycles. Meanwhile, the co-sputtered carbon plays a role in buffering volume change and maintaining electrode structure during further cycling. These results demonstrated that the SiO/C thin film anode has the application prospect as an anode material for lithium-ion batteries.

Influence of carbon coating on the electrochemical performance of SiO@C/graphite composite anode materials**Project supported by the State Grid Technology Project, China (study on the mechanism and characterization of lithium dendrite growth in lithium ion batteries, Project No. DG71-17-010), the National Key Research and Development Program of China (Grant No. 2017YFB0102004), and the National Natural Science Foundation of China (Grant No.

Silicon monoxide (SiO) has been considered as one of the most promising anode materials for next generation high-energy-density Li-ion batteries (LiBs) thanks to its high theoretical capacity. However, the poor intrinsic electronic conductivity and large volume change during lithium intercalation/de-intercalation restrict its practical applications. Fabrication of SiO/C composites is an effective way to overcome these problems. Herein, a series of micro-sized SiO@C/graphite (SiO@C/G) composite anode materials, with designed capacity of , are successfully prepared through a pitch pyrolysis reaction method. The electrochemical performance of SiO@C/G composite anodes with different carbon coating contents of 5 wt%, 10 wt%, 15 wt%, and 35 wt% is investigated. The results show that the SiO@C/G composite with 15-wt% carbon coating content exhibits the best cycle performance, with a high capacity retention of 90.7% at 25 °C and 90.1% at 45 °C after 100 cycles in full cells with LiNi0.5Co0.2Mn0.3O2 as cathodes. The scanning electron microscope (SEM) and electrochemistry impedance spectroscopy (EIS) results suggest that a moderate carbon coating layer can promote the formation of stable SEI film, which is favorable for maintaining good interfacial conductivity and thus enhancing the cycling stability of SiO electrode.

Red Phosphorus-Based Materials As Anode for Na-Ion Batteries K-Ion Batteries

Recently, sodium ion batteries (NIBs) and potassium-ion battery (KIBs) have been attracted much attention since sodium and potassium resource is natural abundant, environmental friendly and showing similar chemical properties with lithium ion batteries. The red P anode for Na-ion and K-ion batteries has attracted great attention recently due to the high theoretical capacity, but the poor intrinsic electronic conductivity and large volume expansion restrains its widespread applications. The intrinsic low electronic conductivity of red P leads to the poor electronic kinetics, large polarization and further low active material utilization. In addition, the large volume expansion (~400%) during Na insertion/extraction in red P leads to pulverization of red P and loose contact between the red P and the current collector, resulting in the severe capacity fading. Herein, we successfully encapsulate the red P into the carbon-based material (such as MOF-derived carbon, N-doped carbon, carbon-nanofibers) via the vaporization-condensation method.1, 2 Superior cycling stability (high capacity retention of about 93% at 2 A g-1 after 100 cycles) and excellent rate performance (502 mAh g-1 at 10 A g-1) could be obtained for the P/C electrode. The superior electrochemical performance could be ascribed to the successful incorporation of red P into the unique carbon matrix with large surface area and pore volume, interconnected porous structure, excellent electronic conductivity and superior structural stability.The porous carbon matrix with abundant micro/meso pores, large pore volume could effectively facilitate the infiltration of the electrolyte, and accommodate large volume expansion of red P during electrochemical process. The excellent conductivity of the carbon could ensure the essential electrical contact to the insulating red P, leading to excellent sodium storage performances. The rational design of the unique red P/ carbon structure could be served as a model for other anode material with poor intrinsic electronic conductivity and large volume expansion.

Porous NaTi2(PO4)3 Nanocubes Anchored on Porous Carbon Nanosheets for High Performance Sodium-Ion Batteries.

NaTi2(PO4)3 has attracted great interest as anode material for sodium ion batteries owing to its open three-dimensional framework structure and limited volume changes during the charge and discharge process. However, the poor intrinsic electronic conductivity of NaTi2(PO4)3 needs to be improved for high rate capability. In this work, porous NaTi2(PO4)3 nanocubes anchored on porous carbon nanosheets (NaTi2(PO4)3/C) are designed and developed. This material exhibits a large discharge capacity and good rate capacity including a first discharge capacity of 485 mAh g−1 at a current density of 0.1 A g−1, and 98 mAh g−1 retained at a high rate of 4 A g−1 even after 2,000 cycles. These results suggest that NaTi2(PO4)3/C is a promising anode material for sodium-ion batteries.

Hierarchical Porous NiO/β-NiMoO4 Heterostructure as Superior Anode Material for Lithium Storage.

Ternary transition metal oxides (TTMOs) have attracted considerable attention for rechargeable batteries because of their fascinating properties. However, the unsatisfactory electrochemical performance originating from the poor intrinsic electronic conductivity and inferior structural stability impedes their practical applications. Here, the novel hierarchical porous NiO/β-NiMoO4 heterostructure is fabricated, and exhibits high reversible capacity, superior rate capability, and excellent cycling stability in Li-ion batteries (LIBs), which is much better than the corresponding single-phase NiMoO4 and NiO materials. The significantly enhanced electrochemical properties can be attributed to its superior structural characteristics, including the large surface area, abundant pores, fast charge transfer, and catalytic effect of the intermediate product of metallic nickel. The NiO/β-NiMoO4 heterostructure delivers a high capacity of 1314 mA h g-1 at 0.2 A g-1 after 100 cycles. Furthermore, even after 400 cycles at 1 A g-1 , the reversible capacity remains at around 500 mA h g-1 . These results indicate that the NiO/β-NiMoO4 heterostructure shows great potential as an anode material for high-performance LIBs.

Lithium iron phosphate electrode semi-empirical performance model

The galvanostatic performance of a pristine lithium iron phosphate (LFP) electrode is investigated. Based on the poor intrinsic electronic conductivity features of LFP, an empirical variable resistance approach is proposed for the single particle model (SPM). The increasing resistance behavior observed at the end of discharge process of LFP batteries can be justified by the increased ohmic resistance, a resistive-reactant feature of LFP as the positive electrode active materials. The model is validated for two different laboratory made Li/LFP coin cells: a high-energy and a high-power configuration. Comparisons between the experimental results and the model predictions reveal that a variable resistance is successful to tackle the increasing overpotential. Schematic of the coated LFP active material particles in (a) beginning of discharge with well-connected particles, (b) end of discharge with poor-connected particles

Cobalt Doping as a Pathway To Stabilize the Solid-State Conversion Chemistry of Manganese Oxide Anodes in Li-Ion Batteries

Metal oxides have been widely studied in recent years to replace commercial graphite anodes in lithium ion batteries. Among the metal oxides, manganese oxide has a high theoretical capacity, low cost, and is environmentally friendly. However, many MnO materials have shown limited reaction reversibility and poor conversion kinetics. To understand why, in this paper we investigate the mechanism, kinetics, and reversibility for the solid-state conversion reaction of MnO with Li+. We definitively show, for the first time, that during repeated reaction cycles, multiple reaction pathways occur that lead not only to the reformation of MnO but also higher oxidation-state Mn3O4—which when combined with the poor intrinsic electronic conductivity of both manganese oxide species results in a rapid loss in the amount of charge that can be stored in these materials. Learning this, the approach in this study was to use cobalt doping to concomitantly stabilize the redox behavior of manganese (allowing for the gradual transformation of MnO to Mn3O4 over time) and to increase the intraparticle electronic conductivity of the active layer. The result is an active material, Mn0.9Co0.1O, that exhibits excellent charge stability and conversion kinetics (near 600 mAh/g at a rate of 400 mA/g), even over hundreds of reaction cycles.

Amorphous Red Phosphorus Embedded in Sandwiched Porous Carbon Enabling Superior Sodium Storage Performances.

The red P anode for sodium ion batteries has attracted great attention recently due to the high theoretical capacity, but the poor intrinsic electronic conductivity and large volume expansion restrain its widespread applications. Herein, the red P is successfully encapsulated into the cube shaped sandwich-like interconnected porous carbon building (denoted as P@C-GO/MOF-5) via the vaporization-condensation method. Superior cycling stability (high capacity retention of about 93% at 2 A g-1 after 100 cycles) and excellent rate performance (502 mAh g-1 at 10 A g-1 ) can be obtained for the P@C-GO/MOF-5 electrode. The superior electrochemical performance can be ascribed to the successful incorporation of red P into the unique carbon matrix with large surface area and pore volume, interconnected porous structure, excellent electronic conductivity and superior structural stability.

Robust three-dimensional graphene skeleton encapsulated Na3V2O2(PO4)2F nanoparticles as a high-rate and long-life cathode of sodium-ion batteries

Na3V2O2(PO4)2F (NVOPF) is a promising cathode material for sodium-ion batteries (SIBs) due to its high working voltage and theoretical capacity. However, the electrochemical performance is strongly impeded by its poor intrinsic electronic conductivity. Herein, we integrated the high flexible graphene sheets with NVOPF through a spray-drying method to re-construct its structure. The NVOPF nanocrystalline particles are homogeneously embedded in the high electronic conductive graphene framework. As a cathode of SIBs, the robust NVOPF/rGO microsphere composite exhibits excellent electrochemical performance: high specific capacity (127.2mAhg−1), long-term cycling stability (83.4% capacity retention at 30C after 2000 cycles) and superior high rate performance (70.3mAhg−1 at 100C). Furthermore, the Na+ insertion/extraction mechanism is also investigated by in-situ XRD and ex-situ HRTEM monitor technologies. This work demonstrates that the constructed 3D graphene skeleton serves as a high-efficient electronic conduction matrix and improves the electrochemical properties of electrode materials for advanced energy storage applications.

Enhanced Conductivity in the Metastable Intermediate in Li x FePO4 Electrode

Olivine LiFePO4 is a major commercial cathode material for lithium ion batteries due to its high specific theoretical capacity, low cost, nontoxicity, and superb thermal/chemical stability. In addition to the above properties, olivine LiFePO4 shows an exceptional high-rate capability despite its poor intrinsic electronic conductivity and sluggish two-phase reaction process. Last year, a non-equilibrium solid solution reaction process was experimentally demonstrated by Grey et al[1]. Independent research was conducted by several groups and confirmed these results[2] , [3]. Recently, we have determined the crystal structure of intermediate Li2/3FePO4 [4]. However, until now there has been no investigation on the transport properties of the metastable intermediate phase formed at the phase boundary interface during the non-equilibrium process due to the following extreme technical difficulties. First, the solid solution phase Li x FePO4 is metastable during electrochemical process and disappears within a few seconds after relaxation[1,3]. We overcame this limitation by quenching Li x FePO4 (x = 0.6) at 350 °C to room temperature. This quenched phase remained stable for a couple of weeks, which enabled sufficient time to measure the intrinsic conductivity. Second, conductive carbon may form during sintering at high temperature from possible carbon sources such as polyolefin worn from jars, organic solvent used in milling and carbon-containing precursors (e.g., oxalate FeC2O4·2H2O). Finally, impurities such as Li3PO4, Li4P2O7 and Fe x P resulting from off-stoichiometric mixing or the carbon reduction effect above 800 °C will largely increase the apparent conductivity of LiFePO4 by several orders of magnitude[5]. The scattering of the LiFePO4 conductivity data resulting from the above extrinsic effects has troubled and confused scientists for a long time. In our present study, pure carbon-free LiFePO4 and FePO4 were prepared using carbon-free precursors and controlling sintering parameters, and the intrinsic conductivity of quenched single phase Li x FePO4 (x = 0.6) was measured. The following figure shows representative Nyquist plots of carbon-free LiFePO4, carbon-free FePO4, and quenched Li0.6FePO4 samples measured at 340 K. Of particular interest is that the electronic resistance of the quenched single-phase Li0.6FePO4 was approximately 2 orders of magnitude smaller than those of the two end-members (LiFePO4 and FePO4) at 340 K. The temperature-dependent conductivity was also measured. Across the entire temperature range of 30 to 350 °C, the single-phase Li0.6FePO4 shows approximately 2 orders of magnitude superior electronic conductivity. The activation energy of Li0.6FePO4 obtained from the slope of the temperature-dependent conductivity was almost identical to the two end members (LiFePO4 and FePO4), which means that the enhanced electronic conductivity originates from the increased charge carrier density. In summary, a metastable solid solution phase Li x FePO4 (x = 0.6) was isolated by the optimized quenching protocol and found to have approximately 2 orders of magnitude enhanced electronic conductivity over the two end members of LiFePO4 and FePO4. Our research reveals that the single-phase transformation mechanism not only relaxes the interface strain energy but also enhances the intrinsic charge transport, enabling the high-rate capability of olivine LiFePO4.