High-performance Lithium Metal Batteries Research Articles

Enabling an Inorganic-Rich Interface via Cationic Surfactant for High-Performance Lithium Metal Batteries

HighlightsCetyltrimethylammonium cations can shield the repelling force on anions to attract more anions into electric double layer region during lithium plating process, facilitating the formation of inorganic-rich solid-state electrolyte interphase (SEI).An inorganic-rich (N/F-containing species) structure of SEI can be evidenced by the in-depth analysis.The cycling lifetime of Li||Li symmetric cell in the designed electrolyte can be extended from 500 to 1300 h. Moreover, full cells with a high cathode mass loading of >10 mg cm-2 can be stably cycled over 180 cycles.

Lithiophilic Hydrogen-Substituted Graphdiyne Aerogels with Ionically Conductive Channels for High-Performance Lithium Metal Batteries.

Lithium (Li) metal stands as a promising anode in advancing high-energy-density batteries. However, intrinsic issues associated with metallic Li, especially the dendritic growth, have hindered its practical application. Herein, we focus on molecular combined structural design to develop dendrite-free anodes. Specifically, using hydrogen-substituted graphdiyne (HGDY) aerogel hosts, we successfully fabricated a promising Li composite anode (Li@HGDY). The HGDY aerogel's lithiophilic nature and hierarchical pores drive molten Li infusion and reduce local current density within the three-dimensional HGDY host. The unique molecular structure of HGDY provides favorable bulk pathways for lithium-ion transport. By simultaneous regulation of electron and ion transport within the HGDY host, uniform lithium stripping/platting is fulfilled. Li@HGDY symmetric cells exhibit a low overpotential and stable cycling. The Li@HGDY||lithium iron phosphate full cell retained 98.1% capacity after 170 cycles at 0.4 C. This study sheds new light on designing high-capacity and long-lasting lithium metal anodes.

Poly (Vinylidene Fluoride-Hexafluoropropylene)-Lithium Titanium Aluminum Phosphate-Based Gel Polymer Electrolytes Synthesized by Immersion Precipitation for High-Performance Lithium Metal Batteries.

Gel polymer electrolytes (GPEs) have high safety and excellent electrochemical performance, so applying GPEs in lithium batteries has received much attention. However, their poor lithium ion transfer number, cycling stability, and low room temperature ionic conductivity seriously affect the utilization of gel polymer electrolytes. This paper successfully synthesized flexible poly (vinylidene fluoride-hexafluoropropylene)-lithium titanium aluminum phosphate (PVDF-HFP-LATP) gel polymer electrolytes using the immersion precipitation method. The resulting GPE has a porous honeycomb structure, which ensures that the GPE has sufficient space to store the liquid electrolyte. The GPE has a high ionic conductivity of 1.03 ×10-3 S cm-1 at room temperature (25 °C). The GPE was applied to LiFePO4/GPE/Li batteries with good rate performance at room temperature. The discharge specific capacity of 1C was as high as 121.5 mAh/g, and the capacity retention rate was 94.0% after 300 cycles. These results indicate that PVDF-HFP-LATP-based GPEs have the advantage of simplifying the production process and can improve the utility of gel polymer lithium metal batteries.

Integrating N, P, Ni into 3D carbon felt anode for high-performance lithium metal batteries

Integrating N, P, Ni into 3D carbon felt anode for high-performance lithium metal batteries

Stabilizing LiNi0.8Co0.1Mn0.1O2 cathode by combined moisture and HF digestion/adsorption for high-performance lithium metal batteries

Nickel-rich layered oxide cathodes such as LiNi0.8Co0.1Mn0.1O2 are promising to significantly increase the energy density of lithium metal batteries beyond 350 Wh kg−1. However, serious issues regarding cycle stability still remain when matching with conventional non-aqueous carbonate electrolytes that contain fluorine such as lithium hexafluorophosphate (LiPF6). Hydrolysis of LiPF6 generates corrosive hydrofluoric acid (HF), which destroys the cathode structure and accelerates the cathodic dissolution/anodic deposition of transition metal (TM) ions. Here, we demonstrate that ball milling NCM811 with carbon-coated aluminum nitride (AlN-C) remarkably enhances the capacity retention. AlN-C acts both as a scavenger and as an adsorption center to digest and adsorb H2O and HF, respectively. Thereby, it prevents the dissolution of TM ions, which would result in capacity decay and damage to the lithium metal anode. It is demonstrated that the addition of AlN-C via wet ball milling with NCM811 enables retaining a specific capacity of 149.9 mA h g−1 after 250 cycles (capacity retention: 85.2 %) at 1 C even in a high moisture electrolyte containing ∼0.2 % (v/v) H2O. Therefore, this work shows up a pathway to a rational enhancement of the capacity retention and cycle life of nickel-rich cathodes.

Janus Quasi-Solid Electrolyte Membranes with Asymmetric Porous Structure for High-Performance Lithium-Metal Batteries

HighlightsJanus quasi-solid electrolyte membranes with asymmetric porous structure were constructed, showing a high σLi+ of 1.5 × 10-4 S cm-1 and a high t+ of 0.71.The solvation structures and ion transport dynamics in nanopores have been deciphered, manifesting a concentrated electrolyte-like structure and regulated transport behaviors.Quasi-solid NCM 622||Li cells have been demonstrated to stably cycle for 200 cycles at 1 C, and pouch cell has shown high tolerance for abuse.

Triple-function eutectic solvent additive for high performance lithium metal batteries

Rational carbonate electrolyte chemistry is critical for the development of high-voltage lithium metal batteries (LMBs). However, the implementation of traditional carbonate electrolyte is greatly hindered by the generation of an unstable electrode interphase and corrosive by-product (HF). Herein, we propose a triple-function eutectic solvent additive of N-methylacetamide (NmAc) with LiNO3 to enhance the stability and compatibility of carbonate electrolyte. Firstly, the addition of NmAc significantly improves the solubility of LiNO3 in carbonate electrolyte by forming an eutectic pair, which regulates the Li+ solvation structure and leads to dense and homogenous Li plating. Secondly, the hydrolysis of acidic PF5 is effectively alleviated due to the strong complexation of NmAc with PF5, thus reducing the generation of corrosive HF. In addition, the optimized cathode electrolyte interphase layer decreases the structural degradation and transition metal dissolution. Consequently, Li||LiNi0.6Co0.2Mn0.2O2 (NCM622) cells with the designed electrolyte deliver superior long-term cycle reversibility and excellent rate capability. This study unveils the rationale for incorporating eutectic solvent additives within carbonate electrolytes, which significantly contribute to the advancement of their practical application for high-voltage LMBs.

Lithiophilic Covalent Organic Framework as Anode Coating for High-Performance Lithium Metal Batteries.

The growth of disorganized lithium dendrites and weak solid electrolyte interphase greatly impede the practical application of lithium metal batteries. Herein, we designed and synthesized a new kind of stable polyimide covalent organic frameworks (COFs), which have a high density of well-aligned lithiophilic quinoxaline and phthalimide units anchored within the uniform one-dimensional channels. The COFs can serve as an artificial solid electrolyte interphase on lithium metal anode, effectively guiding the uniform deposition of lithium ions and inhibiting the growth of lithium dendrites. The unsymmetrical Li||COF-Cu battery exhibits a Coulombic efficiency of 99 % at a current density of 0.5 mA cm-2 , which can be well retained up to 400 cycles. Meanwhile, the Li-COF||LFP full cell shows a Coulombic efficiency over 99 % at a charge of 0.3 C. And its capacity can be well maintained up to 91 % even after 150 cycles. Therefore, the significant electrochemical cycling stability illustrates the feasibility of employing COFs in solving the disordered deposition of lithium ions in lithium metal batteries.

SnCl4 initiated formation of polymerized solid polymer electrolytes for lithium metal batteries with fast ion transport interfaces

Solid-polymer-electrolytes (SPEs) are under active consideration for their high-energy and safe electrochemical energy storage. However, conventional polymer electrolytes are facing poor electrolyte/electrode interfacial contact and undesired lithium dendrite problems. Here, we report a polymerized-dioxolane (P-DOL) electrolytes created by in situ polymerization of DOL in the presence of tin tetrachloride (SnCl4), which enables ultra-conformal interfacial contact with all cell components. More importantly, SnCl4 plays a dual function by initiating ring-opening polymerization of DOL and simultaneously forming a LiCl/LixSn-based alloy composite protective layer on Li metal anodes. The robust Li-rich ion conductive alloys coupled with an electronically insulating surface component form fast ion transport channels. Using the SnCl4-initiated P-DOL SPEs exhibits a high ionic conductivity (>2 mS cm−1) and a wide electrochemical window (4.7 V) at room temperature. Applications of P-DOL SPEs in Li/Li symmetric and Li/LiFePO4 batteries further demonstrate low polarization and high capacity retention. This work provides a facile and practical approach to designing P-DOL SPEs for high-performance lithium metal batteries.

Long-Range Uniform Deposition of Ag Nanoseed on Cu Current Collector for High-Performance Lithium Metal Batteries.

Uniform lithium deposition is essential to hinder dendritic growth. Achieving this demands even seed material distribution across the electrode, posing challenges in correlating the electrode's surface structure with the uniformity of seed material distribution. In this study, the effect of periodic surface and facet orientation on seed distribution is investigated using a model system consisting of a wrinkled copper (Cu)/graphene structure with a [100] facet orientation. A new methodology is developed for uniformly distributed silver (Ag) nanoparticles over a large area by controlling the surface features of Cu substrates. The regularly arranged Ag nanoparticles, with a diameter of 26.4nm, are fabricated by controlling the Cu surface condition as [100]-oriented wrinkled Cu. The wrinkled Cu guides a deposition site for spherical Ag nanoparticles, the [100] facet determines the Ag morphology, and the presence of graphene leads to spacings of Ag seeds. This patterned surface and high lithiophilicity, with homogeneously distributed Ag nanoparticles, lead to uniform Li+ flux and reduced nucleation energy barrier, resulting in excellent battery performance. The electrochemical measurements exhibit improved cyclic stability over 260 cycles at 0.5mAcm-2 and 100 cycles at 1.0mAcm-2 and enhanced kinetics even under a high current density of 5.0mAcm-2.

High concentration in situ polymer gel electrolyte for high performance lithium metal batteries.

A high concentration gel polymer electrolyte (GPE) was prepared by simply using LiFSI-LiNO3 dissolved in 1,3-dioxolane. The Li‖Li cell achieves stable battery cycling for over 3200 h. Furthermore, the Li‖Cu cell demonstrates a high CE of 99.2%. Even at a high current density of 8 mA cm-2, a high CE of 98.5% was still achieved. Notably, in a Li‖LiFePO4 cell, this electrolyte enables high capacity retention of 94.5% and an average CE of 99.8% over 500 cycles, showing promising prospects for high-performance lithium metal batteries.

Synthesis of a crosslinked ether-based polymer for high-performance semi-solid lithium metal batteries via in situ integration

The synergistic effect of the crosslinking molecular design of poly(1,3-dioxolane) and the HOMO–LUMO screening of high voltage resistant fluorinated solvents realizes high-performance lithium metal batteries.

In situ polymerization of 1,3-dioxolane and formation of fluorine/boron-rich interfaces enabled by film-forming additives for long-life lithium metal batteries.

In situ polymerized 1,3-dioxolane (PDOL) is widely utilized to construct solid polymer electrolytes because of its high room-temperature ionic conductivity and good compatibility with lithium metal. However, the current polymerization additives used in PDOL do not effectively contribute to the formation of a robust solid electrolyte interphase (SEI), leading to decreased cycle life. Herein, a film-forming Lewis acid, tris(hexafluoroisopropyl) borate (THB), is demonstrated not only to be a catalyst for the ring-opening polymerization of DOL, but also an additive for the formation of a stable fluorine- and boron-rich SEI to improve the interfacial stability and suppress the Li dendrite growth. Moreover, molecular dynamics simulations and experimental results demonstrate that the introduction of THB can promote the dissociation of lithium salt and release more Li+ while the boron site can effectively restrict the free movement of TFSI- anion, thus increasing Li+ transference numbers (0.76) and ensuring the long-term cycling stability of cells. By using THB-PDOL, a stable cycling of Li‖Li symmetric cell for 600 h at a capacity of 0.5 mA h cm-2 can be achieved. Furthermore, employing THB-PDOL in Li‖LiFePO4 full cell enables a capacity retention of 98.64% after 300 cycles at 1C and a capacity retention of 95.39% after 200 cycles at a high temperature (60 °C). At the same time, this electrolyte is also suitable for the Li‖NCM523 full cell, which also achieves excellent stability of more than 180 cycles. This film-forming Lewis acid additive provides ideas for designing low-cost, high-performance PDOL-based lithium metal batteries.

Fabrication of a synergistic dual-functional layer-modified Cu current collector using a Co-FCVA apparatus for high-performance anode-free lithium metal batteries

A novel Co-FCVA device was employed to prepare a synergistic dual-functional layer-modified Cu current collector for anode-free lithium metal batteries (AFLMBs), which provides an effective solution for the large-scale commercialization of AFLMBs.

Mechanism of lithium dendrite growth on iron surfaces toward high-performance and safe anode-free lithium metal batteries

Selecting the Fe(111) surface, reducing surface cracks, and controlling the surface nanogroove structures can effectively prevent the formation of irreversible Li dendrites on the Fe collector, resulting in better performance of anode-free LMBs.

Synergistic effect of the PMIA nanofiber membrane with a dual-oriented network structure and Li0.5Bi0.5TiO3 nanofibers for high-performance lithium metal batteries

Solid-state lithium metal batteries are favored for their superior energy density and safety compared to liquid batteries.

Stable cyclic ether as an electrolyte additive for high-performance lithium metal batteries.

Introducing a methyl group into 1,3-dioxolane (DOL) to obtain a stable cyclic ether, 4-methyl-1,3-dioxolane (4-Me DOL), allows it to be used as an additive in LiPF6-based carbonate electrolytes. The addition of 4-Me DOL can form a stable SEI with good Li+ transport ability, which can simultaneously improve the rate capability and cycling performance of lithium metal batteries.

Ferroelectric BiFeO3 modified PVDF-based electrolytes for high-performance lithium metal batteries

PVDF-based electrolytes are promising candidates for solid-state lithium batteries (SSLBs) due to their high safety, interface compatibility and electrochemical stability.

Vertically Aligned Hollow Mesoporous Silica Rods Enabling Composite Polymer Electrolytes with Fast Ionic Conduction for Lithium Metal Batteries

AbstractIncorporation of inorganic fillers into polymer matrices to design composite polymer electrolytes is considered as a promising strategy for high performance lithium metal batteries. However, the randomly dispersed fillers in the polymer matrices can cause tortuous ionic channels and increase the transport distance, resulting in the decrease of ion transport capacity. Herein, composite polymer electrolytes with vertically aligned channels are fabricated under the assistance of a magnetic field during the UV‐induced polymerization. The vertically aligned rods are formed through controlling the direction of the magnetic field. The construction of the aligned ionic pathways can effectively reduce the transport distance of Li ions in the electrolytes, while the hollow mesoporous silica rods can provide space for absorbing electrolyte, consequently enhancing the electrochemical kinetics. The aligned interfaces provide Lewis acid sites for trapping the anions of Li salt to facilitate the enhancement of Li ion transference number. More significantly, the Li/Li symmetrical cells based on the composite electrolyte exhibit a stable voltage plateau over 1500 h due to the uniform distribution of Li‐ion flux in the unique low‐tortuosity structure, and the assembled LiFePO4/Li cells show outstanding rate capability and cycling stability.

Stepwise Optimization of Single-Ion Conducting Polymer Electrolytes for High-Performance Lithium-Metal Batteries

Single-ion conducting polymer electrolytes (SIPEs) are among the most promising candidates for high-energy and high-safety lithium-metal batteries. Nevertheless, their commonly limited ionic conductivity and electrochemical stability hamper their practical application. Herein, three new SIPEs, i.e., poly (1,4-phenylene ether ether sulfone)-Li, polysulfone-Li, and hexafluoropolysulfone-Li, all comprising covalently tethered perfluorinated ionic side chains, were designed, synthesized, and comparatively investigated to unveil the influence of the backbone chemistry and the concentration of the ionic group on their electrochemical properties and the eventual cell performance. In particular, the trifluoromethyl group in the backbone and the concentration of the ionic group turn out to play an important role for the charge transport and electrochemical stability towards oxidation. As a result, the combination of both leads to the best-performing SIPE with a high ionic conductivity of ca. 2.5 × 10-4 S cm-1, an anodic stability of >4.8 V, and the best cycling stability in Li‖LiNi0.6Co0.2Mn0.2O2 cells.