Search

While sulfide solid electrolytes such as Na11Sn2PS12 can allow fast transport of Na+ ions, their utilization in solid sodium ion batteries is rather unsuccessful since they are not electrochemically compatible to both high‐voltage cathodes and sodium metal anode. In this work, we devise an effective approach toward realizing solid sodium ion batteries, using the Na11Sn2PS12 electrolyte and slurry‐coated NASICON‐type Na3MnTi(PO4)3@C as high‐voltage cathode, highly beneficial for low processing cost and high content/loading of active cathode matter. We report that through significantly improved integrity of electrolyte‐cathode interface, such solid sodium ion batteries can deliver outstanding cycling and rate performance, with a charge voltage resilience up to 4.1 V, a high cathode discharge capacity of 128.7 mAh g−1 against the Na3MnTi(PO4)3@C in cathode is achieved at 0.05 C, and capacity retention ratio of 82% with a rate of 0.1 C is realized after prolonged cycling at room temperature. Besides, we demonstrate that such a solid sodium ion battery can even perform at a sub‐zero Celsius temperature of −10°C, when the conventional control cell using liquid electrolyte completely fail to function. This work is to offer a dependable avenue in engineering next generation of safe solid ion batteries based on highly sustainable and much cheaper material resources. [ABSTRACT FROM AUTHOR]

The main bottleneck against industrial utilization of sodium ion batteries (SIBs) is the lack of high‐capacity electrodes to rival those of the benchmark lithium ion batteries (LIBs). Here in this work, we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few‐layer graphene sheets loaded with ultrafine SnO2 nanocrystals, using short exposure of microwave to xerogel of graphene oxide (GO) and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO (RGO). The resultant nanocomposites (SnO2@MWG) enabled significantly quickened redox processes as SIB anode, which led to remarkable full anode‐specific capacity reaching 538 mAh g−1 at 0.05 A g−1 (about 1.45 times of the theoretical capacity of graphite for the LIB), in addition to outstanding rate performance over prolonged charge–discharge cycling. Anodes based on the optimized SnO2@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g−1, and capacity retention of over 70.4% was maintained at a high areal loading of 3.4 mg cm−2, highly desirable for high energy density SIBs to rival the current benchmark LIBs. [ABSTRACT FROM AUTHOR]

Heteroatom doped graphene materials are considered as promising anode for high‐performance sodium‐ion batteries (SIBs). Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics; however, the unwanted side reaction at the anode hinders the practical application of SIBs. In this work, a precisely controlled Al2O3 coated nitrogen doped vertical graphene nanosheets (NVG) anode material has been proposed, which exhibits excellent sodium storage capacity and cycling stability. The ultrathin Al2O3 coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte, both alleviating the electrolyte decomposition and enhancing sodium adsorption ability. As a result, the optimal Al2O3 coated NVG materials delivers a high reversible capacity (835.0 mAh g−1) and superior cycling stability (retention of 92.3% after 5000 cycles). This work demonstrates a new way to design graphene‐based anode materials for high‐performance sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Halide solid-state electrolytes (SSEs) have attracted great attention as potential electrolytes for all solid-state batteries (ASSBs) owing to their high oxidation potentials, excellent ductility, and good resilience to humidity. However, to date most reported halide SSEs only demonstrated rather limited ionic conductivities due to lack of effective diffusion channels for fast transportation of lithium ions. Here in this work, we have carried out extensive first principles calculations towards identifying novel candidates as highly attractive halide SSEs, and we find that through tuning the lattice chemistry in the hexagonal Li3YCl6 halide, one is able to open a new avenue in achieving three highly stable compounds with spinel-like cubic structures. The two best cubic compounds, Li2.125Y0.625Cl4 and Li2.5Y0.5Cl4, are able to offer very efficient three-dimensional highways for Li+ transportation, with their being able to offer remarkable room-temperature Li+ conductivities of 6.11 mS cm−1 and 8.42 mS cm−1 at low activation energies (0.247 eV and 0.244 eV), respectively. In addition to ionic conductivities being several times higher than that of the pristine Li3YCl6 phase, they also have remarkably high oxidation potentials above 4.0 V desirable to accommodate high voltage cathode materials electrochemically. [ABSTRACT FROM AUTHOR]

Rechargeable sodium-ion batteries (SIBs) have great potential as an alternative technology to substitute resource-limited lithium-ion batteries (LIBs). However, there is a greater safety concern in directly employing metallic sodium as the anode due to sodium being highly active chemically. It is also very challenging to develop SIB electrodes with high capacity as sodium ions are significantly larger and heavier than lithium ions. Here, in this work, we adopted a materials genome approach based on the density functional theory to screen stable phases through intercalating Na+ into a standard layered MXene phase of Ti4C2O4. It is highly appealing to note that each of the resultant series of MXene compounds of NaxTi4C2O4 (0 ≤ x ≤ 12) can maintain the layered structure of Ti4C2O4 through a fairly large extent of Na+ intercalation. The electrochemical potential vs. Na/Na+ is reversely correlated to the Na content: from 2.96 V and 2.40 V for NaxTi4C2O4 (1 ≤ x ≤ 2) down to 0.05 V for Na12Ti4C2O4. The total capacity for Na12Ti4C2O4 exceeds 579.00 mA h g−1, and this makes it a very promising high-capacity candidate as an anode for SIBs, since the structural integrity of the battery cells would be readily maintained over discharging/charging cycles. Besides, the O-terminated Ti4C2O4 layers are hydrophobic and oxygen-resistant; thus, the intercalated Na would be well protected in ambient processing conditions. [ABSTRACT FROM AUTHOR]