Solid‐state polymer electrolytes (SPEs) with flexibility, easy processability, and low cost have been regarded as promising alternatives for conventional liquid electrolytes in next‐generation ...high‐safety lithium metal batteries. However, SPEs generally suffer poor strength to block Li dendrite growth during the charge/discharge process, which severely limits their wide practical applications. Here, a rational design of 3D cross‐linked network asymmetric SPE modified with a metal–organic framework (MOF) layer on one side is proposed and prepared through an in‐situ polymerization process. In such unique asymmetric SPEs, the nanoscale MOF layer acts as a shield that effectively suppresses the growth of Li dendrites and regulates the uniform Li+ transport, and the polymer electrolyte can be scattered in the whole cell to endow the smooth transmission of Li+. As a result, the asymmetric SPE exhibits high ionic conductivity, wide electrochemical window, high thermal stability and safety, which endows the Li/Li symmetrical cell with outstanding cyclic stability (operate well over 800 h at a current density of 0.1 mA cm−2 for the capacity of 0.1 mAh cm−2).
Asymmetric solid‐state polymer electrolytes (SPEs) modified with an ultrathin metal–organic framework (MOF) layer on one side is constructed via an in situ polymerization process. The nanoscale MOF layer acts as a shield that suppresses the growth of Li dendrites and regulates uniform Li+ transport. Consequently, the lithium metal batteries based on such SPEs exhibit long cycle stability and high safety.
Rechargeable magnesium batteries (RMBs), which have attracted tremendous attention in large‐scale energy storage applications beyond lithium ion batteries, have many advantages such as high ...volumetric capacity, low cost, and environmental friendliness. However, the strong polarization effect, slow kinetic de‐intercalation of Mg2+ ions, and the incompatibility between electrodes and electrolytes limit their commercial application. Thus, developing stable and high‐efficiency electrode materials and optimization of electrolytes are key to promoting the practical application of RMBs. In this review, a summary and discussion are provided regarding the recent progress in the development of the key materials for RMBs, including cathodes, anodes, and electrolytes. The cathode materials including intercalation type cathodes and conversion type cathodes are classified and introduced in detail by the reaction mechanism, the effects of structure on the kinetics of Mg2+ ion migration are clarified; the modification and interface issues of Mg anode materials are comprehensively stated, and the potential development prospects of RMB electrolytes are systematically analyzed. In addition, the main opportunities and challenges in this field are briefly elaborated and discussed. Finally, this review will provide a framework for the key materials for RMBs as a reference for future research.
This review comprehensively summarizes and discusses the recent progress in the key materials for rechargeable magnesium batteries (RMBs) including cathodes, anodes, and electrolytes. The challenges and opportunities in this field are systematically analyzed. This work will provide valuable references for achieving the high specific capacity and long‐lifespan RMBs in the near future.
Solid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature ...conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10−4 S cm−1), a wide electrochemical window (4.6 V vs Li+/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO4 (Al2O3 @ LiNi0.5Co0.2Mn0.3O2), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g−1 (150.7 mAh g−1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.
The intercalated composite solid electrolyte presents a large ionic conductivity and high ionic transference number. The synergistic effect of the high transference number intercalated electrolytes and 3D lithium anode effectively suppresses lithium dendrites. The assembled batteries deliver a high cycling performance, demonstrating a promising strategy for ambient‐temperature solid‐state lithium metal batteries.
The construction of bifunctional electrode materials for hydrogen evolution reaction (HER) and lithium‐ion batteries (LIBs) has been a hot topic of research. Herein, metal–organic frameworks (MOFs) ...derived micro‐/nanostructured Ni2P/Ni hybrids with a porous carbon coating (denoted as Ni2P/Ni@C) are prepared using a feasible pyrolysis–phosphidation strategy. On the one hand, the optimal Ni2P/Ni@C catalyst exhibits superior HER performance with a low overpotential of 149 mV versus a reversible hydrogen electrode (RHE) at 10 mA cm−2 and excellent durability. The density functional theory computations verify that the strong synergistic effect between Ni2P and Ni could optimize the electronic structure, thus rendering the enhanced electrocatalytic performance. On the other hand, the Ni2P/Ni@C electrode displays a reversible capacity of 597 mAh g−1 after 1000 cycles at 1000 mA g−1 and improved rate capability as an anode for LIBs, owing to the well‐organized micro‐/nanostructure and conductive Ni core. In addition, the electrochemical reaction mechanism of the Ni2P/Ni@C electrode upon lithiation/delithiation is investigated in detail via ex situ X‐ray powder diffraction and X‐ray photoelectron spectroscopy methods. It is expected that the facile and controllable approach can be extended to fabricate other MOF‐based metal phosphides/metal hybrids for electrochemical energy storage and conversion systems.
Metal‐organic framework derived micro/nano‐structured Ni2P/Ni hybrids with a porous carbon coating are successfully prepared. As hydrogen evolution reaction catalysts, both experimental and computational results verify that the strong synergistic effect between Ni2P and Ni renders an enhanced electrocatalytic performance. As anode for Li‐ion batteries, the well‐organized micro/nano‐structure and the conductive Ni core jointly promote the electrochemical reaction kinetics.
Thin solid‐state electrolytes with nonflammability, high ionic conductivity, low interfacial resistance, and good processability are urgently required for next‐generation safe, high energy density ...lithium metal batteries. Here, a 3D Li6.75La3Zr1.75Ta0.25O12 (LLZTO) self‐supporting framework interconnected by polytetrafluoroethylene (PTFE) binder is prepared through a simple grinding method without any solvent. Subsequently, a garnet‐based composite electrolyte is achieved through filling the flexible 3D LLZTO framework with a succinonitrile solid electrolyte. Due to the high content of garnet ceramic (80.4 wt%) and high heat‐resistance of the PTFE binder, such a composite electrolyte film with nonflammability and high processability exhibits a wide electrochemical window of 4.8 V versus Li/Li+ and high ionic transference number of 0.53. The continuous Li+ transfer channels between interconnected LLZTO particles and succinonitrile, and the soft electrolyte/electrode interface jointly contribute to a high ambient‐temperature ionic conductivity of 1.2 × 10−4 S cm−1 and excellent long‐term stability of the Li symmetric battery (stable at a current density of 0.1 mA cm−2 for over 500 h). Furthermore, as‐prepared LiFePO4|Li and LiNi0.5Mn0.3Co0.2O2|Li batteries based on the thin composite electrolyte exhibit high discharge specific capacities of 153 and 158 mAh g−1 respectively, and desirable cyclic stabilities at room temperature.
Thin, flexible, and nonflammable composite solid electrolytes with plastic crystals in a 3D garnet‐based framework are prepared by a facile, solvent‐free method, and these unique composite solid electrolytes with high ionic conductivity and low interfacial resistance endow LiFePO4|Li and LiNi0.5Mln0.3Co0.2O2|Li cells with high discharge specific capacities, and desirable cyclic stabilities at room temperature.
The pursuit of high reversible capacity and long cycle life for rechargeable batteries has gained extensive attention in recent years, and the development of applicable electrode materials is the key ...point. Herein, thanks to the preintercalation of lithium ions, a stable and highly conductive nanostructure of V2C MXene is successfully fabricated via a facile self‐discharge mechanism, which provides open spaces for rapid ion diffusion and guarantees fast electron transport. Taking the prelithiated V2C as electrode, an outstanding initial coulombic efficiency of 80% and an impressive capacity retention of ≈98% after 5000 charge/discharge cycles are achieved for lithium‐ion batteries. Especially, it demonstrates a fascinating reversible capacity of up to 230.3 mA h g−1 at 0.02 A g−1 and a long cycling life of 82% capacity retention over 480 cycles in the hybrid magnesium/lithium‐ion batteries. In addition, the Mg2+ and Li+ ions cointercalation mechanism of the prelithiated V2C is elucidated through ex situ X‐ray diffraction and X‐ray photoelectron spectroscopy characterizations. This work not only offers an effective approach to compensate the large initial lithium loss of high‐capacity anode materials but also opens up a new and viable avenue to develop promising hybrid Mg/Li‐storage materials with eminent electrochemical performance.
Prelithiated V2C MXene with a stable and highly conductive nanostructure is prepared through a facile self‐discharge mechanism. The preintercalation of Li+ enables improved initial coulombic efficiency and enhances cycling performance in Li‐ion batteries; exceptional rate capability and unprecedentedly long cycling life are also achieved for Mg2+/Li+ cointercalation chemistry.
Li metal is one of the most promising anode materials for high energy density batteries. However, uncontrollable Li dendrite growth and infinite volume change during the charge/discharge process lead ...to safety issues and capacity decay. Herein, a carbonized metal–organic framework (MOF) nanorod arrays modified carbon cloth (NRA‐CC) is developed for uniform Li plating/stripping. The carbonized MOF NRAs effectively convert the CC from lithiophobic to lithiophilic, decreasing the polarization and ensuring homogenous Li nucleation. The 3D interconnected hierarchal CC provides adequate Li nucleation sites for reducing the local current density to avoid Li dendrite growth, and broadens internal space for buffering the volume change during Li plating/stripping. These characteristics afford a stable cycling of the NRA‐CC electrode with ultrahigh Coulombic efficiencies of 96.7% after 1000 h cycling at 2 mA cm−2 and a prolonged lifespan of 200 h in the symmetrical cell under ultrahigh areal capacity (12 mAh cm−2) and current (12 mA cm−2). The solid‐state batteries assembled with the composite Li anode, high‐voltage cathode (LiNi0.5Co0.2Mn0.3O2), and composite solid‐state electrolyte also deliver excellent cyclic and rate performance at 25 °C. This work sheds fresh insights on the design principles of a dendrite‐free Li metal anode for safe solid‐state Li metal batteries.
Dendrite‐free Li anodes can be achieved through a carbonized Co‐based zeolitic imidazolate framework nanorod arrays modified carbon cloth (NRA‐CC). Owing to the synergistic effect of the interconnected carbon cloth and lithiophilic Co–N–C NRAs, NRA‐CC can regulate the Li plating/stripping behavior and withstand high areal capacity and current density. The composite Li anode is successfully applied in solid‐state Li metal batteries.
Sulfide solid electrolytes (SSEs) for all‐solid‐state Li metal batteries (ASSLMBs) are attracting increasing attention due to their ultrahigh ionic conductivity and good machinability. However, ...current SSEs generally suffer from inferior Li metal compatibility and poor air‐stability, which severely impede their practical applications for ASSLMBs. Herein, novel argyrodite‐based SSEs of Li6+2xP1−xBixS5−1.5xO1.5xCl are synthesized via the Bi, O co‐doping the Li6PS5Cl for the first time. By adjusting the concentrations of dopant, the optimized Li6.04P0.98Bi0.02S4.97O0.03Cl presents an ultrahigh ionic conductivity (3.4 × 10−3 S cm−1). Moreover, such electrolyte displays splendid structural stability after exposure to humid air and chlorobenzene, demonstrating admirable air‐stability and solvent‐stability. The mechanism of the enhanced air‐stability of oxide‐doped SSEs is profoundly understood by conducting first‐principles density functional theory calculations. In addition, the Li6.04P0.98Bi0.02S4.97O0.03Cl electrolyte triggers the generation of LiBi alloy at the anode interface, which plays a crucial role in reducing Li+ diffusion energy barriers and improving interfacial compatibility, leading to an ultrahigh critical current density of 1.1 mA cm−2 and splendid cyclic stability in Li symmetric cell. As a result, ASSLMBs equipped with either pristine or air‐exposed Li6.04P0.98Bi0.02S4.97O0.03Cl can deliver satisfying discharge specific capacity at room temperature.
Argyrodite‐based electrolyte of Li6.04P0.98Bi0.02S4.97O0.03Cl is synthesized successfully via Bi, O co‐doping the Li6PS5Cl for the first time. As‐prepared electrolyte exhibits high ionic conductivity, high air stability, and good Li metal compatibility. Moreover, either pristine or air‐exposed Li6.04P0.98Bi0.02S4.97O0.03Cl can be used as a single electrolyte layer to enable all‐solid‐state Li metal batteries with superior electrochemical performance.
In solid polymer electrolytes (SPEs) based Li–metal batteries, the inhomogeneous migration of dual‐ion in the cell results in large concentration polarization and reduces interfacial stability during ...cycling. A special molecular‐level designed polymer electrolyte (MDPE) is proposed by embedding a special functional group (4‐vinylbenzotrifluoride) in the polycarbonate base. In MDPE, the polymer matrix obtained by copolymerization of vinylidene carbonate and 4‐vinylbenzotrifluoride is coupled with the anion of lithium‐salt by hydrogen bonding and the “σ‐hole” effect of the CF bond. This intermolecular interaction limits the migration of the anion and increases the ionic transfer number of MDPE (tLi+ = 0.76). The mechanisms of the enhanced tLi+ of MDPE are profoundly understood by conducting first‐principles density functional theory calculation. Furthermore, MDPE has an electrochemical stability window (4.9 V) and excellent electrochemical stability with Li–metal due to the CO group and trifluoromethylbenzene (ph‐CF3) of the polymer matrix. Benefited from these merits, LiNi0.8Co0.1Mn0.1O2‐based solid‐state cells with the MDPE as both the electrolyte host and electrode binder exhibit good rate and cycling performance. This study demonstrates that polymer electrolytes designed at the molecular level can provide a broader platform for the high‐performance design needs of lithium batteries.
Molecular‐level designed polymer electrolyte with high ionic transfer number and wide electrochemical window is developed by molecular level design and used as a binder for the cathode active material of lithium‐ion batteries. The all‐solid‐state lithium metal battery with high reversible capacity and low interfacial impedance is prepared by the coating process that improved the cycle capability and energy density of the full battery.
Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have ...extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm−2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li4Ti5O12 or LiFePO4 as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.
A Li–Ni composite anode is achieved via a thermal infusion strategy. It exhibits stable voltage profiles (90 mV at 1.0 mA cm−2) with small hysteresis beyond 100 cycles, as well as low dimension change and effective dendrite inhibition after 100 cycles in a symmetric cell.
