Ti3C2Tx, a typical representative among the emerging family of 2D layered transition metal carbides and/or nitrides referred to as MXenes, has exhibited multiple advantages including metallic ...conductivity, a plastic layer structure, small band gaps, and the hydrophilic nature of its functionalized surface. As a result, this 2D material is intensively investigated for application in the energy storage field. The composition, morphology and texture, surface chemistry, and structural configuration of Ti3C2Tx directly influence its electrochemical performance, e.g., the use of a well‐designed 2D Ti3C2Tx as a rechargeable battery anode has significantly enhanced battery performance by providing more chemically active interfaces, shortened ion‐diffusion lengths, and improved in‐plane carrier/charge‐transport kinetics. Some recent progresses of Ti3C2Tx MXene are achieved in energy storage. This Review summarizes recent advances in the synthesis and electrochemical energy storage applications of Ti3C2Tx MXene including supercapacitors, lithium‐ion batteries, sodium‐ion batteries, and lithium–sulfur batteries. The current opportunities and future challenges of Ti3C2Tx MXene are addressed for energy‐storage devices. This Review seeks to provide a rational and in‐depth understanding of the relation between the electrochemical performance and the nanostructural/chemical composition of Ti3C2Tx, which will promote the further development of 2D MXenes in energy‐storage applications.
2D MXenes have gained attention as one promising kind of materials for electrochemical energy storage due to their high conductivity, layered structure, and tunable electrical/mechanical properties. Herein, for Ti3C2Tx MXene, recent advances in synthesis strategies, tailored properties, and material design are reviewed, along with detailed examples of energy‐storage applications, including lithium‐ion batteries, sodium‐ion batteries, lithium–sulfur batteries, and supercapacitors.
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To promote the development of solid‐state batteries, polymer‐, oxide‐, and sulfide‐based solid‐state electrolytes (SSEs) have been extensively investigated. However, the disadvantages of these SSEs, ...such as high‐temperature sintering of oxides, air instability of sulfides, and narrow electrochemical windows of polymers electrolytes, significantly hinder their practical application. Therefore, developing SSEs that have a high ionic conductivity (>10−3 S cm−1), good air stability, wide electrochemical window, excellent electrode interface stability, low‐cost mass production is required. Herein we report a halide Li+ superionic conductor, Li3InCl6, that can be synthesized in water. Most importantly, the as‐synthesized Li3InCl6 shows a high ionic conductivity of 2.04×10−3 S cm−1 at 25 °C. Furthermore, the ionic conductivity can be recovered after dissolution in water. Combined with a LiNi0.8Co0.1Mn0.1O2 cathode, the solid‐state Li battery shows good cycling stability.
A superionic conductor, Li3InCl6, with room‐temperature Li+ conductivity of 2.04×10−3 S cm−1, is prepared by a facile and scalable water‐mediated synthesis route. The reversible conversion between Li3InCl6 and Li3InCl6⋅2 H2O makes it stable against air and humidity, thus ensuring the high ionic conductivity is recovered after conversion.
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LiNi0.6Co0.2Mn0.2O2 (NCM) is a highly potential cathode material for lithium-ion batteries (LIBs). However, its poor rate capability and cycling performance at high cutoff voltages have seriously ...hindered further commercialization. In this study, we successfully design an ultra-thin lithium aluminum oxide (LiAlO2) coating on NCM for LIBs. Compared to Al2O3, the utilization of lithium-ion conducting LiAlO2 significantly improves the NCM performance at high cutoff voltages of 4.5/4.7V. The study reveals that the LiAlO2-coated NCM can maintain a reversible capacity of more than 149mAhg−1 after 350 cycles with 0.078% decay per cycle. Furthermore, LiAlO2-coated NCM exhibits higher rate capacities 206.8mAhg−1 at 0.2C (50mAg−1) and 142mAhg−1 at 3C than the Al2O3-coated NCM (196.9mAhg−1 at 0.2C and 131.9mAhg−1 at 3C). Our study demonstrates that the ultra-thin LiAlO2 coating is superior to Al2O3 and significantly improves the capacity retention and rate capability of NCM for LIBs.
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•The ultra-thin Al2O3 and LiAlO2 coatings were successfully designed onto NCM.•The optimized coating prevents the cathode from reacting with the electrolyte.•The optimized coating benefits lithium ion transfer upon cycling.•The LiAlO2 coating was more effective in improving NCM performance than Al2O3.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The development of new materials and the understanding of the microstructure formation of electrodes have become increasingly important for improving Li-ion battery performance. In this study, we ...investigate the effect of solid content on the rheological properties of and the microstructures in the cathode slurry prepared from Ni-rich materials. With long-chain structures, PVDF molecules can change their configurations when they come into contact with the solid particles in slurries, and their bridging function can change with the solid content in the slurry. Below the optimum content, particle sedimentation easily takes place. Above the optimum content, excessive yield stress is created in the slurry, and this stress is not conducive to homogeneous distribution of the components. The rheological properties of the slurries vary greatly under different solid contents. We investigated the uniformity and stability of the slurry prepared from Ni-rich materials and found that the most suitable solid content of the slurry lies in the range from 63.9% to 66.3%. Our work might assist in the production of high-performance Li-ion batteries that are made using an electrode slurry.
There are three main situations in which the uniformity and microstructure of the slurry change with the solid content.
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Sulfide‐based solid‐state electrolytes (SSEs) for all‐solid‐state Li metal batteries (ASSLMBs) are attracting significant attention due to their high ionic conductivity, inherently soft properties, ...and decent mechanical strength. However, the poor incompatibility with Li metal and air sensitivity have hindered their application. Herein, the Sn (IV) substitution for P (V) in argyrodite sulfide Li6PS5I (LPSI) SSEs is reported, in the preparation of novel LPSI‐xSn SSEs (where x is the Sn substitution percentage). Appropriate aliovalent element substitutions with larger atomic radius (R > R) provides the optimized LPSI‐20Sn electrolyte with a 125 times higher ionic conductivity compared to that of the LPSI electrolyte. The high ionic conductivity of LPSI‐20Sn enables the rich I‐containing electrolyte to serve as a stabilized interlayer against Li metal in sulfide‐based ASSLMBs with outstanding cycling stability and rate capability. Most importantly, benefiting from the strong Sn–S bonding in Sn‐substituted electrolytes, the LPSI‐20Sn electrolyte shows excellent structural stability and improved air stability after exposure to O2 and moisture. The versatile Sn substitution in argyrodite LPSI electrolytes is believed to provide a new and effective strategy to achieve Li metal‐compatible and air‐stable sulfide‐based SSEs for large‐scale applications.
Partially replacing P with Sn in argyrodite Li6PS5I (LPSI) electrolytes can significantly improve the ionic conductivity (125 times higher), Li metal compatibility, and air stability at the same time. This three‐in‐one strategy provides a new idea to alleviate the problems associated with sulfide‐based solid‐state electrolytes.
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All‐solid‐state Li–S batteries are promising candidates for next‐generation energy‐storage systems considering their high energy density and high safety. However, their development is hindered by the ...sluggish electrochemical kinetics and low S utilization due to high interfacial resistance and the electronic insulating nature of S. Herein, Se is introduced into S cathodes by forming SeSx solid solutions to modify the electronic and ionic conductivities and ultimately enhance cathode utilization in all‐solid‐state lithium batteries (ASSLBs). Theoretical calculations confirm the redistribution of electron densities after introducing Se. The interfacial ionic conductivities of all achieved SeSx–Li3PS4 (x = 3, 2, 1, and 0.33) composites are 10−6 S cm−1. Stable and highly reversible SeSx cathodes for sulfide‐based ASSLBs can be developed. Surprisingly, the SeS2/Li10GeP2S12–Li3PS4/Li solid‐state cells exhibit excellent performance and deliver a high capacity over 1100 mAh g−1 (98.5% of its theoretical capacity) at 50 mA g−1 and remained highly stable for 100 cycles. Moreover, high loading cells can achieve high areal capacities up to 12.6 mAh cm−2. This research deepens the understanding of Se–S solid solution chemistry in ASSLB systems and offers a new strategy to achieve high‐performance S‐based cathodes for application in ASSLBs.
SeSx solid solutions as highly stable and reversible cathodes for sulfide‐based all‐solid‐state lithium batteries are proposed. High electronic/ionic conductivities are achieved in SeSx–Li3PS4 composites, thus facilitated electron/Li+ migration and high‐rate and high‐capacity all‐solid‐state Li–SeSx batteries are realized.
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Development of alternative cathode materials is of highly desirable for sustainable and cost-efficient lithium-ion batteries (LIBs) in energy storage fields. In this study, for the first time, we ...report tunable nitrogen-doped graphene with active functional groups for cathode utilization of LIBs. When employed as cathode materials, the functionalized graphene frameworks with a nitrogen content of 9.26 at% retain a reversible capacity of 344 mAh g–1 after 200 cycles at a current density of 50 mA g–1. More surprisingly, when conducted at a high current density of 1 A g–1, this cathode delivers a high reversible capacity of 146 mAh g–1 after 1000 cycles. Our current research demonstrates the effective significance of nitrogen doping on enhancing cathode performance of functionalized graphene for LIBs.
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IJS, KILJ, NUK, PNG, UL, UM
The development of all‐solid‐state Li metal batteries (ASSLMBs) has attracted significant attention due to their potential to maximize energy density and improved safety compared to the conventional ...liquid‐electrolyte‐based Li‐ion batteries. However, it is very challenging to fabricate an ideal solid‐state electrolyte (SSE) that simultaneously possesses high ionic conductivity, excellent air‐stability, and good Li metal compatibility. Herein, a new glass‐ceramic Li3.2P0.8Sn0.2S4 (gc‐Li3.2P0.8Sn0.2S4) SSE is synthesized to satisfy the aforementioned requirements, enabling high‐performance ASSLMBs at room temperature (RT). Compared with the conventional Li3PS4 glass‐ceramics, the present gc‐Li3.2P0.8Sn0.2S4 SSE with 12% amorphous content has an enlarged unit cell and a high Li+ ion concentration, which leads to 6.2‐times higher ionic conductivity (1.21 × 10−3 S cm−1 at RT) after a simple cold sintering process. The (P/Sn)S4 tetrahedron inside the gc‐Li3.2P0.8Sn0.2S4 SSE is verified to show a strong resistance toward reaction with H2O in 5%‐humidity air, demonstrating excellent air‐stability. Moreover, the gc‐Li3.2P0.8Sn0.2S4 SSE triggers the formation of Li–Sn alloys at the Li/SSE interface, serving as an essential component to stabilize the interface and deliver good electrochemical performance in both symmetric and full cells. The discovery of this gc‐Li3.2P0.8Sn0.2S4 superionic conductor enriches the choice of advanced SSEs and accelerates the commercialization of ASSLMBs.
A new glass‐ceramic Li3.2P0.8Sn0.2S4 solid‐state electrolyte is developed to simultaneously possess high ionic conductivity (10−3 S cm−1 level at room temperature), excellent air‐stability (dry room operable), and good Li metal compatibility. It is expected that this finding can help to accelerate the commercialization of all‐solid‐state Li metal batteries.
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Solid‐state electrolytes (SEs) with high anodic (oxidation) stability are essential for achieving all‐solid‐state Li‐ion batteries (ASSLIBs) operating at high voltages. Until now, halide‐based SEs ...have been one of the most promising candidates due to their compatibility with cathodes and high ionic conductivity. However, the developed chloride and bromide SEs still show limited electrochemical stability that is inadequate for ultrahigh voltage operations. Herein, this challenge is addressed by designing a dual‐halogen Li‐ion conductor: Li3InCl4.8F1.2. F is demonstrated to selectively occupy a specific lattice site in a solid superionic conductor (Li3InCl6) to form a new dual‐halogen solid electrolyte (DHSE). With the incorporation of F, the Li3InCl4.8F1.2 DHSE becomes dense and maintains a room‐temperature ionic conductivity over 10−4 S cm−1. Moreover, the Li3InCl4.8F1.2 DHSE exhibits a practical anodic limit over 6 V (vs Li/Li+), which can enable high‐voltage ASSLIBs with decent cycling. Spectroscopic, computational, and electrochemical characterizations are combined to identify a rich F‐containing passivating cathode‐electrolyte interface (CEI) generated in situ, thus expanding the electrochemical window of Li3InCl4.8F1.2 DHSE and preventing the detrimental interfacial reactions at the cathode. This work provides a new design strategy for the fast Li‐ion conductors with high oxidation stability and shows great potential to high‐voltage ASSLIBs.
A dual‐halogen solid electrolyte Li3InCl4.8F1.2 is developed with excellent electrochemical stability, which is contributed by F‐containing interphases. Li3InCl4.8F1.2 exhibits great potential for high‐voltage all‐solid‐state lithium‐ion batteries.
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