Unraveling the advances of trace doping engineering for potassium ion battery anodes via tomography

Doping have been considered as a prominent strategy to stabilize crystal structure of battery materials during the insertion and removal of alkali ions.The instructive knowledge and experience acquired from doping strategies predominate in cathode materials,but doping principle in anodes remains unclear.Here,we demonstrate that trace element doping enables stable conversion-reaction and ensures structural integrity for potassium ion battery(PIB) anodes.With a synergistic combination of X-ray tomography,structural probes,and charge reconfiguration,we encode the physical origins and structural evolution of electro-chemo-mechanical degradation in PIB anodes.By the multiple ion transport pathways created by the orderly hierarchical pores from "surface to bulk" and the homogeneous charge distribution governed in doped nanodomains,the anisotropic expansion can be significantly relieved with trace isoelectronic element doping into the host lattice,maintaining particle mechanical integrity.Our work presents a close relationship between doping chemistry and mechanical reliability,projecting a new pathway to reengineering electrode materials for next-generation energy storage.

Porous conductive interlayer for dendrite-free lithium metal battery

Lithium(Li) metal,possessing ultrahigh theoretical capacity and the lowest electrode potential,is regarded as a promising new generation anode material.However,the uncontrollable growth of Li dendrites during cycling process gives rise to problems as capacity decay and short circuit,suppressing the cycling and safety performances of Li metal battery.In this contribution,porous conductive interlayer(PCI),composed of carbon nanofibers(CNFs) and polyisophthaloyl metaphenylene diamine(PMIA),is developed to suppress Li dendrites and stabilize Li metal anode.PCI possesses the excellent conductive ability of CNFs and the preeminent mechanical properties of PMIA at the same time.When Li metal contacts with PCI during cycling process,an equipotential surface forms on their interface,which eliminates the tip effect on Li anode and homogenizes Li-ions flux in combination with the uniform porous structure of PCI.Employed PCI,the Li|Cu cell exhibits a remarkable cycling stability with a high average Coulombic efficiency of 97.5% for 100 cycles at 0.5 mA cm^(-2).And the Li|LiFePO_4 cell exhibits improved rate capability(114.7 mAh g^(-1) at 5.0 C) and enhanced cycling performance(78.9% capacity retention rate over 500 cycles at 1.0 C).This work provides a fresh and effective solving strategy for the problem of dendrites in Li metal battery.