STUDY ON THE STRUCTURE, ELECTRICAL PROPERTIES AND CONDUCTION MECHANISM 0F THE MULTICRYSTAL MULTIPHASE MATERIAL Li_2MO_2-xWxO_6

The conductivity of non-crystalline fast ionic conductor for B_2O_3-Li_2O-LiCl-Al_2O_3 system is studiedin this paper. The glass structure of this system is discussed by means of infrared spectrum and X-ray fluorescence analysis, and the effects of LiCl and A1_2O_3 on the conductivity of Li^+ in the system are studied as well. Adding Li_2O to the system gives rise to transfer from [BO_3] triangular units to [BO_4] tetrahedral. When Li_2O content exceeds 30mol%, the main group of the glass is the diborate group with more [BO_4] tetrahedra. The adding of LiCl has no obvious influence on the glass structure, and LiCl is under a state dissociated by network, but with the increase of LiCl, the increase of conductivity is obvious. By adding A1_2O_3, the glass can be formed when the room-temperature is cooling down,the conductivity decreases while the conductive activatory energy increases for the glass. The experiment shows that conductivity in the room-temperature is σ= 6.2×10^(-6)Ω^(-1)cm^(-1), when at 300℃, the σ=6.8×10^(-3)Ω^(-1)cm^(-1). The conductive activatory energy computed is 0.6～1.0eV.

Ionic liquids for high performance lithium metal batteries

The pursuit of high energy density has promoted the development of high-performance lithium metal batteries.However,it faces a serious security problem.Ionic liquids have attracted great attention due to their high ionic conductivity,non-flammability,and the properties of promoting the formation of stable SEI films.Deeply understanding the problems existing in lithium metal batteries and the role of ionic liquids in them is of great significance for improving the performance of lithium metal batteries.This article reviews the effects of the molecular structure of ionic liquids on ionic conductivity,Li^(+)ion transference number,electrochemical stability window,and lithium metal anode/electrolyte interface,as well as the application of ionic liquids in Li-high voltage cathode batteries,Li-O_(2) batteries and Li-S batteries.The molecular design,composition and polymerization will be the main strategies for the future development of ionic liquid-based electrolytes for high performance lithium metal battery.

Low cost and low density chloride solid electrolyte for all solid state cathode with high active material ratio

Chloride solid electrolytes(SEs)have attracted widespread attention due to their high room-temperature ionic conductivity and excellent cathode compatibility.However,the conventionally selected central metal elements(e.g.,In,Y and Ta)are usually rare and heavy,inevitably causing the high cost and high density of the obtained chloride SEs.Here,by choosing abundant and light Mg and Al as central metal elements,we develop a cheap and low density Li_(1.2)Mg_(0.95)Al_(0.3)Cl_(4)SE for high active material ratio in all solid state cathode.Partial replacement of Mg^(2+)by Al^(3+)in the framework yields vacancies and lowers the non-lithium metal ions occupancy at Mg/Li co-occupied 16d site,effectively relieving the blocking effects by Mg^(2+)in the pristine spinel Li_(2-2x)Mg_(1+x)Cl_(4).Thus,a significantly improved room-temperature conductivity of 3.08×10^(-4)S·cm^(-1)is achieved,two orders of magnitude higher than that of Li_(1.2)Mg_(1.4)Cl_(4).More attractively,its low density of only 1.98 g·cm-3 enables low SE mass ratio in cathodes(only 16 wt.%)with still effective electrolyte/cathode contact and lithium-ion conduction inside.When charged to potential of 4.30 V,the asfabricated Li_(1.2)Mg_(0.95)Al_(0.3)Cl_(4)-based solid lithium battery with uncoated NCM523 cathode can be cycled for over 100 cycles with a capacity retention of 86.68%at room temperature.

Electrolyte design for Li-conductive solid-electrolyte interphase enabling benchmark performance for all-solid-state lithium-metal batteries

Sulfide-based solid-state electrolytes (SSEs) with high Li+ conductivity (δLi^(+)) and trifling grain boundaries have great potential for all-solid-state lithium-metal batteries (ASSLMBs). Nonetheless, the in-situ development of mixed ionic-electronic conducting solid-electrolyte interphase (SEI) at sulfide electrolyte/Li-metal anode interface induces uneven Li electrodeposition, which causes Li-dendrites and void formation, significantly severely deteriorating ASSLMBs. Herein, we propose a dual anionic, e.g., F and N, doping strategy to Li7P3S11, tuning its composition in conjunction with the chemistry of SEI. Therefore, novel Li_(6.58)P_(2.76)N_(0.03)S_(10.12)F_(0.05) glass-ceramic electrolyte (Li_(7)P_(3)S_(11-5)LiF-3Li_(3)N-gce) achieved superior ionic (4.33 mS·cm^(−1)) and lowest electronic conductivity of 4.33 × 10^(−10) S·cm^(−1) and thus, offered superior critical current density of 0.90 mA·cm^(−2) (2.5 times 】Li7P3S11) at room temperature (RT). Notably, Li//Li cell with Li6.58P2.76N0.03S10.12F0.05-gce cycled stably over 1000 and 600 h at 0.2 and 0.3 mA·cm^(−2) credited to robust and highly conductive SEI (in-situ) enriched with LiF and Li3N species. Li3N’s wettability renders SEI to be highly Li+ conductive, ensures an intimate interfacial contact, blocks reductive reactions, prevents Li-dendrites and facilitates fast Li+ kinetics. Consequently, LiNi0.8Co0.15Al0.05O_(2) (NCA)/Li_(6.58)P_(2.76)N_(0.03)S_(10.12)F_(0.05)-gce/Li cell exhibited an outstanding first reversible capacity of 200.8/240.1 mAh·g^(−1) with 83.67% Coulombic efficiency, retained 85.11% of its original reversible capacity at 0.3 mA·cm^(−2) over 165 cycles at RT.

Regulating Li^(+)migration and Li_(2)S deposition by metal-organic framework-derived Co_(4)S_(3)-embedded carbon nanoarrays for durable lithium-sulfur batteries

The shuttle effect of lithium polysulfides and the uncontrollable deposition of lithium sulfides(Li_(2)S)severely hinder the realization of high-performance lithium-sulfur(Li-S)batteries.Herein,we fabricated a carbon cloth(CC)-based self-supported interlayer(denoted as Co_(4)S_(3)/C@CC),which is covered with Co_(4)S_(3)-embedded porous carbon nanoarrays through a facile two-step method with cobalt-based metal-organic framework(Co-MOF)nanosheets as the template.The interconnected carbon network and the polar Co_(4)S_(3) nanoparticles in the Co_(4)S_(3)/C@CC interlayer not only effectively suppress the polysulfide shuttle,but also significantly facilitate the lithium ion(Li^(+))conduction with a considerable Li^(+)transference number of 0.86.Besides,the rich interfaces between the polar Co_(4)S_(3) nanoparticles and the conductive carbon substrate serve as reaction sites to accelerate the polysulfide conversion and guide the flower-like growth of Li_(2)S,which ultimately mitigates the interlayer surface passivation and improves the sulfur utilization.Therefore,the Li-S batteries with the Co_(4)S_(3)/C@CC interlayer deliver an excellent rate capacity(368.7 mA h g^(−1) at 10 C),a stable cycling performance(a low fading rate of 0.045%per cycle over 1400 cycles at 2.0 C),and a high initial areal capacity(4.83 mA h cm^(−2) at 0.2 C under a sulfur loading of 4.6 mg cm^(−2)).This work provides a perspective on the self-supported catalytic interlayer for the selective Li^(+)conduction and Li_(2)S regulation toward high-performance Li-S batteries.

Maximizing ionic transport of Li1+xAlxTi2-xP3O12 electrolytes for all-solid-state lithium-ion storage:A theoretical study

The concept of all-solid-state batteries provides an efficient solution towards highly safe and long-life energy storage,while the electrolyte-related challenges impede their practical application.Li1+xAlxTi2-xP3O12(0≤x≤1)with superior Li ionic conductivity holds the promise as an ideal solidstate electrolyte.The intrinsic mechanism to reach the most optimum ionic conductivity in Al-doped Li1+xAlxTi2-xP3O12,however,is unclear to date.Herein,this work intends to provide an atomic scale study on the Li-ion transport in Li1+xAlxTi2-xP3O12electrolyte to rationalize how Al-dopant initiates interstitial Li activity and facilitate their easy mobility combining Density Functional Theory(DFT)and ab initio Molecular dynamics(AIMD)simulations.It is discovered that the interstitial Li ions introduced by Al dopants can effectively activate the neighboring occupied intrinsic Li-ions to induce a long-range mobility in the lattice and the maximum Li ionic conductivity is achieved at 0.50 Al doping concentration.The Li-ion migration paths in Li1+xAlxTi2-xP3O12have investigated as the degree of distortion of[PO4]tetrahedra and[TiO6]octahedra resulted by different Al doping concentrations.The asymmetry of the surrounding distorted[PO4]and[TiO6]polyhedrons play a critical role in reducing the migration barrier of Li ions in Li1+xAlxTi2-xP3O12.The flexible[Ti O6]polyhedrons with a capacity to accommodate the structural distortion govern the Li ionic conductivity in Li1+xAlxTi2-xP3O12.This work rationalizes the mechanism for the most optimum Li ionic conductivity in Al-doped Li Ti2P3O12electrolyte and,more importantly,paves a road for exploring novel all-solid-state lithium battery electrolytes.