An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries

Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries(ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions(e.g. corrosion and hydrogen evolution)in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.

Skin care design for lithium metal protection with cosmetics introduction

Lithium metal anode(LMA)is the ultimate"Holy Grail"electrode for next generation high-energy-density batteries.Nevertheless,its instinct high reactivity is a formidable challenge and has intensified side reactions,destabilized the electrode/electrolyte interface and restricted the operating conditions strictly,thus hampering its practical application.Here,we"make up"the Li metal(M-Li)by constructing vaselinecoated layer by a simple dip-coating or casting method.With the chemically stable and hydrophobic vaseline protective layer,the stability of Li towards humid and corrosive atmosphere has been greatly improved.The M-Li guaranteed stable and prolonged cycling life after the anode suffering from corrosion in moist air(relative humidity-65%)or corrosive electrolyte(with 10,000 ppm H2O or S)both in symmetric cells and LiFePO4 full cells.This work illustrates a convenient,economic,and industrial applicable method for stable LMA.

Revealing the solid electrolyte interface on calcium metal anodes

Owing to its low potential, crustal abundances and environmental friendliness, calcium metal anode(CMA) is emerging as a powerful contender in post-lithium era. However, the passivation of CMA fatally hinders its development. Recently, several feasible electrolytes have been developed. Nevertheless, as a pivotal part, the solid electrolyte interface(SEI) formed on CMA has not been paid enough attention to. In this review, based on the passivation mechanism of CMA, the favorable composition of SEI is emphasized with the corresponding electrolytes. It is considered that boron-containing and organic–inorganic hybrid SEI might be preferred. By comparing electrolytes and SEI on CMA with lithium and magnesium metal anodes, the root causes of CMA passivation are further elaborated, enlightening rational design rules of suitable SEI. Furthermore, some noteworthy details when assembling secondary calcium metal batteries(CMBs) are put forward. It is expected that deeper understanding of SEI on CMA will promote the development of CMBs.

Processable Potassium Metal Anode for Stable Batteries

The future of high-energy density electrochemical energy storage systems relies on the advancement of rechargeable batteries that utilize reactive metals as anodes.In the alkaline metal,secondary battery systems because of abundant resource,high capacity and low redox potential,potassium(K)metal secondary battery(KMB)is expected to replace the existing lithiumion battery as a versatile platform for high-energy density,cost-effective energy storage devices.However,the difficulty in processing metal K results in nonstandard electrodes and hinders the development of KMBs.Furthermore,the mobility of the K metal anode due to its unique lowmelting point character at elevated temperatures in practical conditions leads to severe instability and risks in chemical/electrochemical processes.Herein,we fabricate a processable and moldable composite K metal anode by encapsulating K into reduced graphene oxide(rGO).The composite electrode can be engineered into various shapes discretionarily with precise sizes and stabilize the K metal anode at relatively high temperatures.Remarkably,the composite anode exhibits excellent cycling performance at high current density(8 mA cm^(-2)) with dendrite-free morphology.Paired with a Prussian blue cathode,the rGO-K composite anode shows much improved electrochemical performance and extended lifetime.

Crystallographic engineering of Zn anodes for aqueous batteries

With their intrinsic safety and environmental benignity,aqueous Zn-ion batteries(ZIBs)have been considered the most appropriate candidates for replacing alkali metal systems.However,polycrystalline Zn anodes in aqueous environments still pose enormous issues,such as dendrite growth and side reactions.Although many efforts have been made to address these obstacles through interphase modification and electrolyte design,researchers have not been able to improve the inherent thermodynamic stability and ion deposition behavior of the Zn anode.It is imperative to understand and explore advanced anode construction methods from the perspective of crystallinity.This review delves into the feasibility of precisely regulating the crystallographic features of metallic zinc,examines the challenges and merits of reported strategies for fabricating textured zinc,and offers constructive suggestions for the large-scale production and commercial application of aqueous ZIBs.

Data-driven design of high-performance MASnxPb1-xI3 perovskite materials by machine learning and experimental realization

The photovoltaic performance of perovskite solar cell is determined by multiple interrelated factors,such as perovskite compositions,electronic properties of each transport layer and fabrication parameters,which makes it rather challenging for optimization of device performances and discovery of underlying mechanisms.Here,we propose and realize a novel machine learning approach based on forward-reverse framework to establish the relationship between key parameters and photovoltaic performance in high-profile MASnxPb1-xI3 perovskite materials.The proposed method establishes the asymmetrically bowing relationship between band gap and Sn composition,which is precisely verified by our experiments.Based on the analysis of structural evolution and SHAP library,the rapid-change region and low-bandgap plateau region for small and large Sn composition are explained,respectively.By establishing the models for photovoltaic parameters of working photovoltaic devices,the deviation of short-circuit current and open-circuit voltage with band gap in defective-zone and low-bandgap-plateau regions from Shockley-Queisser theory is captured by our models,and the former is due to the deep-level traps formed by crystallographic distortion and the latter is due to the enhanced susceptibility by increased Sn4+content.The more difficulty for hole extraction than electron is also concluded in the models and the prediction curve of power conversion efficiency is in a good agreement with Shockley-Queisser limit.With the help of search and optimization algorithms,an optimized Sn:Pb composition ratio near 0.6 is finally obtained for high-performance perovskite solar cells,then verified by our experiments.Our constructive method could also be applicable to other material optimization and efficient device development.

Synergistic Effects of Salt Concentration and Working Temperature towards Dendrite-Free Lithium Deposition

The lithium-(Li-)metal anode is crucial for developing high-energy-density batteries,while its dendritic growth and the low charge/discharge Coulombic efficiency in organic electrolytes hinder its practical application.Herein,we employed an in situ optical microscope to investigate the effect of the electrolyte concentration and the working temperature on the Li-plating/-stripping process.It is found that a higher concentration electrolyte can suppress its side reaction to improve the charge/discharge Coulombic efficiency,and a higher temperature can help lithium plate/strip uniformly with less lithium dendritic growth.An average Coulombic efficiency was obtained as high as 99.2%for over 150 cycles with a fixed plating capacity of 2 mAh cm^(-2) on copper foil in a 3 mol/kg ether-based electrolyte under 60℃,which provides an efficient and facile strategy for developing high-performance Li-metal batteries.

Ion conduction path in composite solid electrolytes for lithium metal batteries: from polymer rich to ceramic rich

Solid-state electrolytes(SSEs)can address the safety issue of organic electrolyte in rechargeable lithium batteries.Unfortunately,neither polymer nor ceramic SSEs used alone can meet the demand although great progress has been made in the past few years.Composite solid electrolytes(CSEs)composed of flexible polymers and brittle but more conducting ceramics can take advantage of the individual system for solid-state lithium metal batteries(SSLMBs).CSEs can be largely divided into two categories by the mass fraction of the components:“polymer rich”(PR)and“ceramic rich”(CR)systems with different internal structures and electrochemical properties.This review provides a comprehensive and in-depth understanding of recent advances and limitations of both PR and CR electrolytes,with a special focus on the ion conduction path based on polymer-ceramic interaction mechanisms and structural designs of ceramic fillers/frameworks.In addition,it highlights the PR and CR which bring the leverage between the electrochemical property and the mechanical property.Moreover,it further prospects the possible route for future development of CSEs according to their rational design,which is expected to accelerate the practical application of SSLMBs.