Effect of SnO_2 intermediate layer on performance of Ti/SnO_2/MnO_2 electrode during electrolytic-manganese process

SnO2intermediate layers were coated on the titanium(Ti)substrate by thermal decomposition.Scanning electronmicroscope(SEM)and X-ray diffraction(XRD)results show that uniform SnO2intermediate layers with rutile crystal structure weresuccessfully achieved.According to the results of linear sweep voltammetry(LSV),oxygen evolution potential(OEP)of theTi/SnO2/MnO2electrodes decreases with increasing SnO2content,indicating that the electro-catalytic oxidation activity of theelectrode increases.Accelerated service life tests results demonstrate that SnO2intermediate layer can improve the service life of theTi/SnO2/MnO2electrode.As the content of SnO2intermediate layer increases,the cell voltage and the energy consumption decreaseapparently.

Review of silicon-based alloys for lithium-ion battery anodes

Silicon(Si)is widely considered to be the most attractive candidate anode material for use in next-generation high-energy-density lithium(Li)-ion batteries(LIBs)because it has a high theoretical gravimetric Li storage capacity,relatively low lithiation voltage,and abundant resources.Consequently,massive efforts have been exerted to improve its electrochemical performance.While some progress in this field has been achieved,a number of severe challenges,such as the element’s large volume change during cycling,low intrinsic electronic conductivity,and poor rate capacity,have yet to be solved.Methods to solve these problems have been attempted via the development of nanosized Si materials.Unfortunately,reviews summarizing the work on Si-based alloys are scarce.Herein,the recent progress related to Si-based alloy anode materials is reviewed.The problems associated with Si anodes and the corresponding strategies used to address these problems are first described.Then,the available Si-based alloys are divided into Si/Li-active and inactive systems,and the characteristics of these systems are discussed.Other special systems are also introduced.Finally,perspectives and future outlooks are provided to enable the wider application of Si-alloy anodes to commercial LIBs.

Mechanism for capacity fading of 18650 cylindrical lithium ion batteries

The mechanism for capacity fading of18650lithium ion full cells under room-temperature(RT)is discussedsystematically.The capacity loss of18650cells is about12.91%after500cycles.The cells after cycles are analyzed by XRD,SEM,EIS and CV.Impedance measurement shows an overall increase in the cell resistance upon cycling.Moreover,it also presents anincreased charge-transfer resistance(Rct)for the cell cycled at RT.CV test shows that the reversibility of lithium ioninsertion/extraction reaction is reduced.The capacity fading for the cells cycled can be explained by taking into account the repeatedfilm formation over the surface of anode and the side reactions.The products of side reactions deposited on separator are able toreduce the porosity of separator.As a result,the migration resistance of lithium ion between the cathode and anode would beincreased,leading the fading of capacity and potential.

Enhanced cycling stability of La modified LiNi_(0.8-x)Co_(0.1)Mn_(0.1)La_xO_2 for Li-ion battery

A series of layered LiNi0.8?xCo0.1Mn0.1LaxO2(x=0,0.01,0.03)cathode materials were synthesized by combining co-precipitation and high temperature solid state reaction to investigate the effect of La-doping on LiNi0.8Co0.1Mn0.1O2.A new phase La2Li0.5Co0.5O4was observed by XRD,and the content of the new phase could be determined by Retiveld refinement and calculation.The cycle stability of the material is obviously increased from74.3%to95.2%after La-doping,while the initial capacity exhibits a decline trend from202mA·h/g to192mA·h/g.The enhanced cycle stability comes from both of the decrease of impurity and the protection of newly formed La2Li0.5Co0.5O4,which prevents the electrolytic corrosion to the active material.The CV measurement confirms that La-doped material exhibits better reversibility compared with the pristine material.

Enhancing storage performance of P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2)cathode materials by Al_(2)O_(3)coating

The P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2)materials were synthesized by an ultrasonic spray pyrolysis followed by solid-state sintering method.The structures,morphologies and electrochemical performances of Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2)materials were characterized thoroughly by means of X-ray diffractometer,scanning electron microscope and electrochemical charge/discharge instruments.Moreover,a thin layer of Al_(2)O_(3),which was formed on the surface of Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2),can enhance the storage performance by preventing the formation of Na_(2)CO_(3)·H_(2)O,which is believed to enhance the electrochemical performances of Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2)materials.This facile surface modification method may pave a way to synthesize advanced cathode materials for sodium-ion batteries.

Empirical decay relationship between ionic conductivity and porosity of garnet type inorganic solid-state electrolytes

Ionic conductivity is one of the crucial parameters for inorganic solid-state electrolytes.To explore the relationship between porosity and ionic conductivity,a series of Li_(6.4)Ga_(0.2)La_(3)Zr_(2)O_(12) garnet type solid-state electrolytes with different porosities were prepared via solid-state reaction.Based on the quantified data,an empirical decay relationship was summarized and discussed by means of mathematical model and dimensional analysis method.It suggests that open porosity causes ionic conductivity to decrease exponentially.The pre-exponential factor obeys the Arrhenius Law quite well with the activation energy of 0.23 eV,and the decay constant is averaged to be 2.62%.While the closed porosity causes ionic conductivity to decrease linearly.The slope and intercept of this linear pattern also obey the Arrhenius Law and the activation energies are 0.24 and 0.27 eV,respectively.Moreover,the total porosity is linearly dependent on the open porosity,and different sintering conditions will lead to different linear patterns with different slopes and intercepts.

Ultrathin porous graphitic carbon nanosheets activated by alkali metal salts for high power density lithium-ion capacitors

Graphitic carbons with reasonable pore volume and appropriate graphitization degree can provide efficient Li+/electrolyte-transfer channels and ameliorate the sluggish dynamic behavior of battery-type carbon negative electrode in lithium-ion capacitors(LICs).In this work,onion-like graphitic carbon materials are obtained by using carbon quantum dots as precursors after sintering,and the effects of alkali metal salts on the structure,morphology and performance of the samples are focused.The results show that alkali metal salts as activator can etch graphitic carbons,and the specific surface area and pore size distribution are intimately related to the description of the alkali metal salt.Moreover,it also affects the graphitization degree of the materials.The porous graphitic carbons(SGCs)obtained by NaCl activation exhibit high specific surface area(77.14 m^(2)·g^(-1))and appropriate graphitization degree.It is expectable that the electrochemical performance for lithium-ions storage can be largely promoted by the smart combination of catalytic graphitization and pores-creating strategy.High-performance LICs(S-GCs//AC LICs)are achieved with high energy density of 92 Wh·kg^(-1)and superior rate capability(66.3 Wh·kg^(-1)at10 A·g^(-1))together with the power density as high as10020.2 W·kg^(-1).

Trivalent Ni oxidation controlled through regulating lithium content to minimize perovskite interfacial recombination

Organic–inorganic hybrid perovskite solar cells,one of the most promising photovoltaic devices,have made great progress in their efficiency and preparation technology.In this study,uniform,highly conductive Li_(n)NiO_(x)(0≤n≤1;0<x≤3)films were prepared by electrochemical deposition for a range of Li concentration.Photovoltaic performance for the perovskite solar cells was enhanced through incorporation of the ion pair of Ni^(3+)-Ni^(2+) as the interfacial passivation.Depending on the amount of lithium doping,controlled interfacial oxidation was induced by Ni^(3+).The Li_(0.32)NiO_(x)inhibited charge recombination,reduced the defect density,and enhanced the photocurrent density.A maximum power conversion efficiency of 20.44%was obtained by Li_(0.32)NiO_(x).Further,in the long-term,in-air stabilities of unencapsulated Li_(n)-NiO_(x) perovskite solar cells were demonstrated.