Preparation of λ-MnO_2 by Column Method and Its Ion-Sieve Property

MnO 2 was prepared by column method from normal spinel LiMn 2O 4 with purity of 99.38%.The influence of LiMn 2O 4 grain size and acidity of leaching solution on the lithium leaching process was studied.The results show that the appropriate range of LiMn 2O 4 grain size was 60-160 meshes and the concentration of leaching solution HCl was 0.1 mol·L -1.The adsorption capacity Q of λ-MnO 2 for lithium increased with the increase of pH and changed markedly at pH 6.0-10.0.It was 3.80mmol/g at pH 12.0.The distribution coefficients K d of Li + and Na + were 3.406×10 4 and 2.300 respectively,and the separation coefficient α Li Na was 1.481×10 4 at pH 6.5.As a result,λ-MnO 2 is a high performance ion-sieve material for lithium ion.

Phosphorylated cellulose nanofibers establishing reliable ion-sieving barriers for durable lithium-sulfur batteries

The shuttle effect is among the most characteristic and formidable challenges in the pursuit of high-performance lithium-sulfur(Li-S)batteries.Herein,phosphorylated cellulose nanofibers(pCNF)are intentionally engineered to establish an ion-sieving barrier against polysulfide shuttling and thereby improve battery performance.The phosphorylation,involving the grafting of phosphate groups onto the cellulose backbone,imparts an exceptional electronegativity that repels the polysulfide anions from penetrating through the separator.Moreover,the electrolyte wettability and Li^(+)transfer can be significantly promoted by the polar nature of pCNF and the facile Li^(+)disassociation.As such,rational ion management is realized,contributing to enhanced reversibility in both sulfur and lithium electrochemistry.As a result,Li-S cells equipped with the self-standing pCNF separator demonstrate outstanding long-term cyclability with a minimum fading rate of 0.013%per cycle over 1000 cycles at 1 C,and a decent areal capacity of 5.37 mA h cm^(-2) even under elevated sulfur loading of 5.0 mg cm^(-2) and limited electrolyte of 6.0 mL g^(-1).This work provides a facile and effective pathway toward the well-tamed shuttle effect and highly durable Li-S batteries.

Preparation and characterization of lithium λ-MnO2 ion-sieves

Abstract Lithium λ-MnO2 ion-sieves were prepared from spinel LiMn2O4 via treatment with nitric acid. The LiMn2O4 was synthesized by a solid state reaction between LiOH· H2O and MnO2. The effects of the calcination time and temperature on the preparation of the LiMn2O4 precursor and the lithium ion-sieve were investigated. In addition, the Li^＋ extraction ratio, the Mn^2＋ dissolving ratio and the adsorption properties of the lithium ion-sieve were all measured. The lithium ion-sieve had a high exchange capacity and was selective for Li^＋. Specifically, at pH = 13, the ion exchange capacity of Li^＋ was 30.9mg/g in 10 mmol/L LiCl solution and the lithium extraction ratio and manganese dissolving ratio were 95% and 25%, respec- tively.

Preparation of lithium ion-sieve and utilizing in recovery of lithium from seawater

Lithium is one of the most important light metals,which is widely used as raw materials for large-capacity rechargeable batteries,light aircraft alloys and nuclear fusion fuel.Seawater,which contains 250 billion tons of lithium in total,has thus recently been noticed as a possible resource of lithium.While,since the aver-age concentration of lithium in seawater is quite low(0.17 mg$L–1),enriching it to an adequate high density becomes the primary step for industrial applications.The adsorption method is the most prospective technology for increasing the concentration of lithium in liquid.Among the adsorbents for lithium,the ion-sieve is a kind of special absorbent which has high selectivity for Li+,especially the spinel manganese oxides(SMO),which among the series of ion-sieves,has become the most promising adsorption material for lithium.In this study,the SMO ion-sieve was prepared by a coprecipitation method.The preparation conditions were discussed and the sample characters were analyzed.Recovery of Li+from seawater were studied in batch experiments using prepared ion-sieve,and the effect of solution pH and the uptake rates were also investigated in different Li+solutions.

The rise of supercapacitor diodes:Current progresses and future challenges

Supercapacitor has been widely known as a representative electrochemical energy storage device with high power density and long lifespan.Recently,with the deeper understanding of its charge storage mechanism,unidirectional-charging supercapacitor,also called supercapacitor diode(CAPode),is successfully developed based on the ion-sieving effect of its working electrode towards electrolyte ions.Because CAPode integrates mobile ion and mobile electron in one hybrid circuit,it has a great potential in the emerging fields of ion/electron coupling logic operations,human–machine interface,neural network interaction,and in vivo diagnosis and treatment.Accordingly,we herein elucidate the working mechanism and design philosophy of CAPode,and summarize the electrode materials that are suitable for constructing CAPode.Meanwhile,some other supercapacitor-based devices beyond CAPode are also introduced,and their potential applications are instructively presented.Finally,we outline the challenges and chances of CAPode-related techniques.