Acetylene/argon mixture plasma to build ultrathin carbon bridge of CF_(x)/C/MnO_(2) for high-rate lithium primary battery

Forming an ultrathin conducting layer on a fluorinated carbon(CFx)surface for reducing severe electrochemical polarization in lithium/fluorinated carbon primary batteries(Li/CF_(x))remains a considerable challenge for achieving batteries with excellent rate capability.Herein,CFxwas modified by using acetylene/argon mixture plasma combined with MnO_(2)particles.The CF_(x)/C/MnO_(2)composite effectively reduced the voltage hysteresis and improved the electrochemical performance of Li/CF_(x).The excellent rate performance of CF_(x)/C/MnO_(2)was due to the high electrochemical activity provided by the atomicscale conductive carbon layer and ultrafine MnO_(2)particles.Compared with pristine CF_(x),the charge transfer resistance of the optimized CF_(x)/C/MnO_(2)decreased from 218.5 to 48.2Ω,the discharge rate increased from 2C to 10C,and the power density increased from 3.11 to 13.44 kW·g^(-1),The intrinsic reason for the enhanced rate performance was attributed to the fact that the ultrathin carbon layer acted as a conductive bridge to reduce the voltage hysteresis at the initial stage of the Li/CF_(x)discharge,and the high electrochemical activity of the ultrafine MnO_(2)particles provided a faster lithium-ion diffusion rate.

Interface-Structure-Modulated CuF_(2)/CF_(x) Composites for High-Performance Lithium Primary Batteries

Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.

Electrochemical performance of Klason lignin as a low-cost cathode-active material for primary lithium battery

A few classes of organic compounds are promising electrode-active materials due to their high power and energy densities,low cost,environmental friendliness,and functionality.In the present work,the possibility of using Klason lignin extracted from buckwheat husks as a cathode-active material for a primary lithium battery has been investigated for the first time.The reaction mechanism in the lithium/lignin electrochemical cell was suggested based on the deep galvanostatic discharge（up to 0.005 V） data and cyclic voltammetry results.The dependence of the electrochemical behavior of the Klason lignin on the milling degree was evaluated.The maximum specific capacity of the lignin is equal to 600 m Ah g-1at a discharge current density of 75 μA cm-2.Beneficial effect of the thermal treatment of the Klason lignin cathode at250°C on the cell performance was established.It was found that the discharge capacity of the cell increased by 30% in the range from 3.3 to0.9 V for the treated cathode material.These results demonstrate the prospects of using Klason lignin-based electrochemical cells as low-rate primary power sources.

Lithium-ion and solvent co-intercalation enhancing the energy density of fluorinated graphene cathode

Fluorinated carbons CF_xhold the highest theoretical energy density(e.g.,2180 W h kg^(-1)when x=1)among all cathode materials of lithium primary batteries.However,the low conductivity and severe polarization limit it to achieve its theory.In this study,we design a new electrolyte,namely 1 M LiBF_(4)DMSO:DOL(1:9 vol.),achieving a high energy density in Li/CF_xprimary cells.The DMSO with a small molecular size and high donor number successfully solvates Li^(+)into a defined Li^(+)-solvation structure.Such solvated Li^(+)can intercalate into the large-spacing carbon layers and achieve an improved capacity.Consequently,when discharged to 1.0 V,the CF_(1.12)cathode demonstrates a specific capacity of 1944 m A h g^(-1)with a specific energy density of 3793 W h kg^(-1).This strategy demonstrates that designing the electrolyte is powerful in improving the electrochemical performance of CF_(x) cathode.

Ultrahigh Energy Density Li-Organic Primary Batteries

This article is to highlight recent work from Prof.Yunhua Xu published in the Proceedings of the National Academy of Sciences 2022,119,e2116775119.Organic electrode materials are promising candidates for battery electrode materials due to the abundant resource,structural diversity,environmental friendliness,and potential low cost.[1]However,most of reported organic materials rely on one-electron redox reaction per active group.

The Fluorination of Boron-Doped Graphene for CF_(x) Cathode with Ultrahigh Energy Density

The enhancement of the fluorination degree of carbon fluorides(CF_(x))compounds is the most effective method to improve the energy densities of Li/CF_(x)batteries because the specific capacity of CF_(x)is proportional to the molar ratio of F to C atoms(F/C).In this study,B-doped graphene(BG)is prepared by using boric acid as the doping source and then the prepared BG is utilized as the starting material for the preparation of CF_(x).The B-doping enhances the F/C ratio of CF_(x)without hindering the electrochemical activity of the C–F bond.During the fluorination process,B-containing functional groups are removed from the graphene lattice.This facilitates the formation of a defect-rich graphene matrix,which not only enhances the F/C ratio due to abundant perfluorinated groups at the defective edges but also serves as the active site for extra Li+storage.The prepared CF_(x)exhibits the maximum specific capacity of 1204 mAh g^(−1),which is 39.2%higher than that of CF_(x)obtained directly from graphene oxide(without B-doping).An unprecedented energy density of 2974 Wh kg^(−1)is achieved for the asprepared CF_(x)samples,which is significantly higher than the theoretically calculated energy density of commercially available fluorinated graphite(2180 Wh kg^(−1)).Therefore,this study demonstrates a great potential of B-doping to realize the ultrahigh energy density of CF_(x)cathodes for practical applications.

An overview of non-noble metal electrocatalysts and their associated air cathodes for Mg-air batteries

Although metal-air batteries(MABs)including Mg-air batteries possess high theoretical energy densities and are promising in energy storage systems,the poor performances and high cost of corresponding electrocatalysts and air cathodes significantly limit practical application.Based on this,the present review gives a summary of the recent progress in the development of cost effective non-noble metal electrocatalysts and their associated air cathodes for MABs,with a particular focus on Mg-air batteries including the aspects of corresponding catalyst synthesis and characterization,catalyzed oxygen reduction reaction(ORR)mechanism,air cathode fabrication and performance validation.The paper also provides an analysis on the issues that challenge the development of advanced electrocatalysts and the associated air cathodes for Mg-air batteries,as well as a discussion of potential research directions that may help resolve these issues and facilitate the practical application of Mg-air batteries.

Weakly-solvating electrolytes enable ultralow-temperature (-80°C) and high-power CF_(x)/Li primary batteries

Fluorinated carbons(CF_(x))/Li primary batteries with high theoretical energy density have been applied as indispensable energy storage devices with no need for rechargeability,yet plagued by poor rate capability and narrow temperature adaptability in actual scenarios.Herein,benefiting from precise solvation engineering for synergistic coordination of anions and low-affinity solvents,the optimized cyclic ether-based electrolyte is elaborated to significantly facilitate overall reaction dynamics closely correlated to lower desolvation barrier.As a result,the excellent rate(15 C,650 mAh g^(-1))at room-temperature and ultra-lowtemperature performance dropping to-80°C(495 mAh g^(-1)at average output voltage of 2.11 V)is delivered by the end of 1.5 V cut-off voltage,far superior to other organic liquid electrolytes.Furthermore,the CF_(x)/Li cell employing the high-loading electrode(18-22 mg cm^(-2))still yields 1,683 and 1,395 Wh kg^(-1)in the case of-40°C and-60°C,respectively.In short,the novel design strategy for cyclic ethers as basic solvents is proposed to enable the CF_(x)/Li battery with superb subzero performances,which shows great potential in practical application for extreme environments.

Fluorinated graphite nanosheets for ultrahigh-capacity lithium primary batteries

For better performances of Ni-based catalysts at low temperatures,Ni/SiC catalyst doped with a little amount of additive La was successfully prepared.The catalytic CO methanation activity tests showed that 3%La-Ni/SiC catalyst was excellent at a low reaction temperature(95.9%CO conversion and 85.1%CH4 selectivity at250℃)with a superior stability compared with Ni/SiC(3.4%CO conversion and 0%CH4 selectivity at 250℃).This can be attributed to that the addition of La can markedly improve the dispersibility of active metal Ni and reduce the particle sizes of Ni nanoparticles or clusters,and can also regulate the interaction between active components and supports.Moreover,the high thermal conductivity and thermal stability could avoid the generation of hot spots in the catalyst bed.These results will promote the development of highly active Ni-based catalysts for the low-temperature methanation reaction.

Enabling rechargeable Li-MnO_(2) batteries using ether electrolytes

A low-carbon future demands more affordable batteries utilizing abundant elements with sustainable end-of-life battery management.Despite the economic and environmental advantages of Li-MnO_(2)batteries,their applica-tion so far has been largely constrained to primary batteries.Here,we demonstrate that one of the major limiting factors preventing the stable cycling of Li-MnO_(2)batteries,Mn dissolution,can be effectively mitigated by employing a common ether electrolyte,1 mol/L lithium bis(trifluorometha-nesulfonyl)imide(LiTFSI)in 1,3-dioxane(DOL)/1,2-dimethoxyethane(DME).We discover that the suppression of this dissolution enables highly reversible cycling of the MnO_(2)cathode regardless of the synthesized phase and morphology.Moreover,we find that both the LiPF_(6)salt and carbonate solvents present in conventional electrolytes are responsible for previous cycling challenges.The ether electrolyte,paired with MnO_(2)cathodes is able to demonstrate stable cycling performance at various rates,even at elevated temperature such as 60℃.Our discovery not only represents a defining step in Li-MnO_(2)batteries with extended life but provides design criteria of electrolytes for vast manganese-based cathodes in rechargeable batteries.

Magnesium Microspheres and Nanospheres: Morphology- Controlled Synthesis and Application in Mg/MnO_(2) Batteries

In this paper,we report on the morphology-controlled synthesis of magnesium micro/nanospheres and their electrochemical performance as the anode of primary Mg/MnO_(2) batteries.Mg micro/nanoscale materials with controllable shapes have been prepared via a conventional vapor-transport method under an inert atmosphere by adjusting the deposition temperatures.Extensive analysis techniques including SEM,XRD,TEM/HRTEM,and Brunauer Emmett Teller(BET)were carried out to characterize the as-obtained samples.The results show that the Mg samples are microspheres or micro/nanospheres with specific surface areas of 0.611.92 m^(2)/g.The electrochemical properties of the as-prepared Mg and commercial Mg powders were further studied in terms of their linear sweep voltammograms,impedance spectra,and discharge capability.By comparing the performance of different inhibitors in electrolytes,it was found that NaNO2(2.6 mol/L)as an inhibitor in the Mg(NO_(3))_(2)(2.6 mol/L)electrolyte affords a Mg electrode with high current density and low corrosion rate.In particular,the Mg sample consisting of microspheres with a diameter of 1.53.0μm and nanospheres with a diameter of 50150 nm exhibited superior electrode properties including negative initial potential(1.08 V),high current density(163 mA/cm^(2)),low apparent activation energy(5.1 kJ/mol),and high discharge specifi c capacity(784 mAh/g).The mixture of Mg nanospheres and microspheres is promising for application in primary Mg/MnO_(2) batteries because of the suffi cient contact with the electrolyte and greatly reduced charge transfer impedance and polarization.