LiNbO3-coated LiNi0.8Co0.1Mn0.1O2 cathode with high discharge capacity and rate performance for all-solid-state lithium battery

In order to obtain high power density,energy density and safe energy storage lithium ion batteries(LIB)to meet growing demand for electronic products,oxide cathodes have been widely explored in all-solidstate lithium batteries(ASSLB)using sulfide solid electrolyte.However,the electrochemical performances are still not satisfactory,due to the high interfacial resistance caused by severe interfacial instability between sulfide solid electrolyte and oxide cathode,especially Ni-rich oxide cathodes,in charge-discharge process.Ni-rich LiNi0.8Co0.1Mn0.1O2(NCM811)material at present is one of the most key cathode candidates to achieve the high energy density up to 300 Wh kg^-1 in liquid LIB,but rarely investigated in ASSLB using sulfide electrolyte.To design the stable interface between NCM811 and sulfide electrolyte should be extremely necessary.In this work,in view of our previous work,LiNbO3 coating with about 1 wt% content is adopted to improve the interfacial stability and the electrochemical performances of NCM811 cathode in ASSLB using Li10GeP2S12 solid electrolyte.Consequently,LiNbO3-coated NCM811 cathode displays the higher discharge capacity and rate performance than the reported oxide electrodes in ASSLB using sulfide solid electrolyte to our knowledge.

Ameliorating the interfacial issues of all-solid-state lithium metal batteries by constructing polymer/inorganic composite electrolyte

Lithium metal is one of the most promising anodes for next-generation batteries due to its high capacity and low reduction potential.However,the notorious Li dendrites can cause the short life span and safety issues,hindering the extensive application of lithium batteries.Herein,Li_(7)La_(3)Zr_(2)O_(12)(LLZO)ceramics are integrated into polyethylene oxide(PEO)to construct a facile polymer/inorganic composite solid-state electrolyte(CSSE)to inhibit the growth of Li dendrites and widen the electrochemical stability window.Given the feasibility of our strategy,the designed PEO-LLZO-LiTFSI composite solid-state electrolyte(PLLCSSE)exhibits an outstanding cycling property of 134.2 mAh g^(-1) after 500 cycles and the Coulombic efficiency of 99.1%after 1000 cycles at 1 C in LiFePO_(4)-Li cell.When cooperated with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cathode,the PLL-CSSE renders a capacity retention of 82.4%after 200 cycles at 0.2 C.More importantly,the uniform dispersion of LLZO in PEO matrix is tentative tested via Raman and FT-IR spectra and should be responsible for the improved electrochemical performance.The same conclusion can be drawn from the interface investigation after cycling.This work presents an intriguing solid-state electrolyte with high electrochemical performance,which will boost the development of all-solid-state lithium batteries with high energy density.

In/ex-situ Raman spectra combined with EIS for observing interface reactions between Ni-rich layered oxide cathode and sulfide electrolyte

The interfacial instability between Ni-rich layered oxide cathodes and sulfide electrolytes is a serious problem,leading to poor electrochemical properties of all-solid-state lithium batteries(ASSLB).The chemical/electrochemical side reactions are considered to be the origin of the interfacial deterioration.However,the influence of chemical and electrochemical side reactions on the interfacial deterioration is rarely studied specifically.In this work,the deterioration mechanism of the interface between LiNi0.85-xCo0.15AlxO2 and Li10GeP2S12 is investigated in detail by combining in/ex-situ Raman spectra and Electrochemical Impedance Spectroscopy(EIS).It can be determined that chemical side reaction between LiNi0.8Co0.15Al0.05O2 and Li10GeP2S12 will occur immediately once contacted,and the interfacial deterioration becomes more serious after charge-discharge process under the dual effects of chemical and electrochemical side reactions.Moreover,our research reveals that the interfacial stability and the cycle performance of ASSLB can be greatly enhanced by increasing Al-substitution for Ni in LiNi0.85-xCo0.15AlxO2.In particular,the capacity retention of LiNi0.6Co0.15Al0.25O2 cathode after 200 cycles can reach 81.9%,much higher than that of LiNi0.8Co0.15Al0.05O2 cathode(12.5%@200 cycles).This work gives an insight to study the interfacial issues between Ni-rich layered oxide cathode and sulfide electrolyte for ASSLBs.

Temperature field prediction of steel-concrete composite decks using TVFEMD-stacking ensemble algorithm

This research aims to develop an advanced deep learning-based ensemble algorithm,utilizing environmental temperature and solar radiation as feature factors,to conduct hourly temperature field predictions for steel-concrete composite decks(SCCDs).The proposed model comprises feature parameter lag selection,two non-stationary time series decomposition methods(empirical mode decomposition(EMD)and time-varying filtering-based empirical mode decomposition(TVFEMD)),and a stacking ensemble prediction model.To validate the proposed model,five machine learning(ML)models(random forest(RF),support vector regression(SVR),multilayer perceptron(MLP),gradient boosting regression(GBR),and extreme gradient boosting(XGBoost))were tested as base learners and evaluations were conducted within independent,mixed,and ensemble frameworks.Finally,predictions are made based on engineering cases.The results indicate that consideration of lag variables and modal decomposition can significantly improve the prediction performance of learners,and the stacking framework,which combines multiple learners,achieves superior prediction results.The proposed method demonstrates a high degree of predictive robustness and can be applied to statistical analysis of the temperature field in SCCDs.Incorporating time lag features helps account for the delayed heat dissipation phenomenon in concrete,while decomposition techniques assist in feature extraction.

Towards safe lithium-sulfur batteries from liquid-state electrolyte to solid-state electrolyte

Lithium-sulfur(Li-S)battery has been considered as one of the most promising future batteries owing to the high theoretical energy density(2600 W-h-kg-1)and the usage of the inexpensive active materials(elemental sulfur).The recent progress in fundamental research and engineering of the Li-S battery,involved in electrode,electrolyte,membrane,binder,and current collector,has greatly promoted the performance of Li s batteries from the laboratory level to the approaching practical level.However,the safety concerns still deserve attention in the following application stage.This review focuses on the development of the electrolyte for Li S batteries from liquid state to solid state.Some problems and the corresponding solutions are emphasized,such as the soluble lithium polysulfides migration,ionic conductivity of electrolyte,the interface contact between electrolyte and electrode,and the reaction kinetics.Moreover,future perspectives of the safe and high-performance Li S batteries arealso introduced.

Enhancing the reversible capacity and cycle stability of lithium-ion batteries with Li-compensation material Li_(6)CoO_(4)

High-capacity anode materials,such as SiO and Si/C,are considered promising candidates for high-energydensity lithium-ion batteries.However,the low initial Coulombic efficiency of these anode materials induced by side reactions(forming Li_(2)O and lithium silicate)and the formation of solid electrolyte interface film reduces the active Liions and causes low-discharge capacity.Adding a Li-compensation material in the cathode or anode is an effective strategy to overcome this problem.The most used Li-compensation material is the stabilized lithium metal powder.However,this strategy has high safety risks,high costs,and is challenging to quantify.Herein,the Li-compensation material of Li_(6)CoO_(4) is synthesized and investigated.The preparation conditions,stability in the air,delithiation mechanism,and structural transformation are analyzed and discussed.Electrochemical tests reveal that the discharge capacity and capacity retention of the full pouch cells(3-Ah)with Li_(6)CoO_(4) additive is significantly improved.Also,the reason for such improvement is investigated.This work provides an effective strategy of Li-compensating technology to enhance the electrochemical performance of lithium-ion batteries.