Anchoring polysulfide with artificial solid electrolyte interphase for dendrite-free and low N/P ratio Li-S batteries

Lithium sulfur batteries are regarded as a promising candidate for high-energy-density energy storage devices.However,the lithium metal anode in lithium-sulfur batteries encounters the problem of lithium dendrites and lithium metal consumption caused by polysulfide corrosion.Herein we design a dualfunction PMMA/PPC/LiNO3composite as an artificial solid electrolyte interphase(PMCN-SEI)to protect Li metal anode.This SEI offers multiple sites of C=O for polysulfide anchoring to constrain corrosion of Li metal anode.The lithiated polymer group and Li3N in PMCN-SEI can homogenize lithium-ion deposition behavior to achieve a dendrite-free anode.As a result,the PMCN-SEI protected Li metal anode enables the Li||Li symmetric batteries to maintain over 300 cycles(1300 h)at a capacity of 5 m Ah cm^(-2),corresponding to a cumulative capacity of 3.25 Ah cm^(-2).Moreover,Li-S batteries assembled with 20μm of Li metal anode(N/P=1.67)still deliver an initial capacity of 1166 m A h g-1at 0.5C.Hence,introducing polycarbonate polymer/inorganic composite SEI on Li provides a new solution for achieving the high energy density of Li-S batteries.

High rate and cycling stable Li metal anodes enabled with aluminum-zinc oxides modified copper foam

Metallic Li is a promising anode material for high energy density batteries but it suffers from poor stability and formation of unsafe dendrites. Previous studies demonstrated that 3 D metal foams are able to improve the stability of Li metal but the properties of these foams are inherently limited. Here we report a facile surface modification approach via magnetron sputtering of mixed oxides that effectively modulate the properties of Cu foams for supporting Li metal with remarkable stability. We discovered that hybrid Li anodes with Li metal thermally infused to aluminum-zinc oxides(AZO) coated Cu foams have significantly improved stability and reactivity compared with pristine Li foils and Li infused to unmodified Cu foams. Full cells assembled with a Li Fe PO4 cathode and a hybrid anode maintained low and stable charge-transfer resistance(<50) during 500 cycles in carbonate electrolytes, and exhibited superior rate capability(~100 m Ah g-1 at 20 C) along with better electrochemical reversibility and surface stability. The AZO modified Cu foams had superior mechanical strength and afforded the hybrid anodes with minimized volume change without the formation of dendrites during battery cycling. The rational construction of surface architecture to precisely control Li plating and stripping may have great implications for the practical applications of Li metal batteries.

LIMITED MEMORY QUASI-NEWTON METHOD FOR LARGE-SCALE LINEARLY EQUALITY-CONSTRAINED MINIMIZATION

In this paper, a new limited memory quasi-Newton method is proposed and developed for solving large-scale linearly equality-constrained nonlinear programming problems. In every iteration, a linear equation subproblem is solved by using the scaled conjugate gradient method. A truncated solution of the subproblem is determined so that computation is decreased. The technique of limited memory is used to update the approximated inverse Hessian matrix of the Lagrangian function. Hence, the new method is able to handle large dense problems. The convergence of the method is analyzed and numerical results are reported.