Boosting the Electrochemical Performance of Li-and Mn-Rich Cathodes by a Three-in-One Strategy

There are plenty of issues need to be solved before the practi-cal application of Li-and Mn-rich cathodes,including the detrimental voltage decay and mediocre rate capability,etc.Element doping can e ectively solve the above problems,but cause the loss of capacity.The introduction of appropriate defects can compensate the capacity loss;however,it will lead to structural mismatch and stress accumulation.Herein,a three-in-one method that combines cation–polyanion co-doping,defect construction,and stress engineering is pro-posed.The co-doped Na^(+)/SO_(4)^(2-)can stabilize the layer framework and enhance the capacity and voltage stability.The induced defects would activate more reac-tion sites and promote the electrochemical performance.Meanwhile,the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling.Consequently,the modified sample retains a capacity of 273 mAh g^(-1)with a high-capacity retention of 94.1%after 100 cycles at 0.2 C,and 152 mAh g^(-1)after 1000 cycles at 2 C,the corresponding voltage attenuation is less than 0.907 mV per cycle.

Influence of residual stresses on failure pressure of cylindrical pressure vessels

The utilization of pressure vessels in aerospace applications is manifold.In this work,fnite element analysis（FEA）has been carried out using ANSYS software package with 2D axisymmetric model to access the failure pressure of cylindrical pressure vessel made of ASTM A36 carbon steel having weld-induced residual stresses.To fnd out the effect of residual stresses on failure pressure,frst an elasto-plastic analysis is performed to fnd out the failure pressure of pressure vessel not having residual stresses.Then a thermo-mechanical fnite element analysis is performed to assess the residual stresses developed in the pressure vessel during welding.Finally one more elasto-plastic analysis is performed to assess the effect of residual stresses on failure pressure of the pressure vessel having residual stresses.This analysis indicates reduction in the failure pressure due to unfavorable residual stresses.

Enhancing hydrogen evolution of MoS_(2) basal planes by combining single-boron catalyst and compressive strain

M0 S2 is a promising candidate for hydrogen evolution reaction(HER),while its active sites are mainly distributed on the edge sites rather than the basal plane sites.Herein,a strategy to overcome the inertness of the M0 S2 basal surface and achieve high HER activity by combining single-boron catalyst and compressive strain was reported through density functional theory(DFT)computations.The ab initio molecular dynamics(AIMD)simulation on B@MoS2 suggests high thermodynamic and kinetic stability.We found that the rather strong adsorption of hydrogen by B@MoS2 can be alleviated by stress engineering.The optimal stress of -7%can achieve a nearly zero value of △Gh(〜-0.084 eV),which is close to that of the ideal Pt-SACs for HER.The novel HER activity is attributed to(i)the Bdoping brings the active site to the basal plane of M0 S2 and reduces the band-gap,thereby increasing the conductivity;(ii)the compressive stress regulates the number of charge transfer between(H)-(B)-(MoS2),weakening the adsorption energy of hydrogen on B@MoS2.Moreover,we constructed a SiN/B@MoS2 heterojunction,which introduces an 8.6%compressive stress for B@MoS2 and yields an ideal AGh-This work provides an effective means to achieve high intrinsic HER activity for M0 S2.