Research Progress on Negative Electrodes for Practical Li‐Ion Batteries: Beyond Carbonaceous Anodes

Abstract

3 of 43) 1402225 wileyonlinelibrary.comhost matrix is observed and this process is called "topotactic reaction", which is either chemically or thermally reversible; a perfect example is Li-intercalation into a graphite matrix. Such intercalation chemistry has been successfully used in Li-ion batteries for both anode and cathode materials and has also been commercialized (i.e., LiCoO 2 /Li x C 6 and LiFePO 4 /Li x C 6 ). [ 4,5 ] The insertion type materials, i.e., metal oxides have several advantages over graphitic anodes when used in practical cells; these include a negligible amount of ICL, no Li-platting issues, no solvent co-intercalation, no electrolyte decomposition, no SEI required for the safe operation of the cell, it is capable of delivering high power density, and has an easy synthesis protocol. On the other hand, less reversible capacity and higher intercalation potential are the notable setbacks compared to graphite. Although numerous Li-intercalating materials are proposed as possible anodes for LIB applications, few of them have only been tested or commercialized in the "rocking-chair" confi guration, for instance Li 4 Ti 5 O 5 anode. Apart from the mentioned anode, few other insertion type materials have been also evaluated in the rocking-chair confi guration for LIBs. Accordingly, the next section describes the structural and electrochemical performance of various intercalation anodes evaluated in the rocking-chair confi guration. TiO 2The existence of several polymorphs is reported for the case of TiO 2 , but anatase, rutile, brookite, and bronze phases have only been reported for Li-storage. [ 26 ] Reversible insertion of one mole of Li is theoretically possible, independent of the polymorph, with a capacity of ≈335 mAh g −1 . However, variation in the Liinsertion potential and reaction mechanism has been observed for such polymorphs. Easy synthesis protocols, scalability, inexpensiveness, ease of tailoring the desired morphology, and eco-friendliness are other key features for utilizing TiO 2 polymorphs for the construction of Li-ion power packs. [27][28][29] AnataseThe anatase phase is one of the widely investigated polymorphs of TiO 2 for Li-storage. [ 27 ] Theoretically, one mole of Li is possible, but practically only ≈0.5 mole Li is reversible upon cycling. Several research attempts have been carried out to improve the reversible capacity, including utilizing high energy (0 0 1) facets because of their dominant higher surface energy (0.90 J m −2 ) compared to (1 0 0) facets (0.44 J m −2 ) and using thermodynamically more stable (1 0 1) facets (0.53 J m −2 ). [ 30,31 ] Although high Li-reversibility could be achieved for such (0 0 1) facets, capacity fading remains an issue upon cycling. [ 32 ] Li-diffusion co-effi cient ( D Li ) values for anatase phase are in the range of 1 × 10 −17 to 4 × 10 −17 cm 2 s −1 for Li-insertion and extraction processes, respectively. [ 27 ] In the crystal chemistry of the anatase phase, TiO 6 octahedra sharetwo adjacent edges with two other octahedral so that...

Transition‐Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium‐ and Sodium‐Ion Batteries with Excellent Cycling Properties

“…However,t he NCN stretching band is broad and shifted to lower energies compared to pristine FeNCN,inl ine with the formation of an anostructured composite after lithium reaction with FeNCN.N ote that both cycled electrodes contain additional absorption bands originating from the electrolyte constituents,s uch as the PF 6 À anion showing an intense band at 840 cm À1 ,a sw ell as to other compounds formed by their partial decomposition. [47] In summary,t he complete electrochemical reaction of FeNCN with lithium can be formulated as: Analogous reactions can be proposed for the other tested transition-metal carbodiimides,that is,MnNCN,ZnNCN,and Cr 2 (NCN) 3 .…”

Preparation of Three-Dimensional LiMn2O4/Carbon Composite Cathodes Via Sol-Gel Impregnation and Their Electrochemical Performance in Lithium-Ion Battery Application

“…It can be seen that the specific capacities increase with increased filling. Despite the low calcination temperature which is known to inhibit the lithium intercalation [26][27][28] capacities over 100 mAh · g . This value is in good agreement with the results obtained for thin film LMO cathodes 21 rather than conventional paste electrodes.…”

A New Way to Prepare MoO3/C as Anode of Lithium ion Battery for Enhancing the Electrochemical Performance at Room Temperature

“…Although graphite has been extensively employed as anode material in commercial LIBs for many years, its relatively low Li ion storage capacity (theoretical capacity of 372 mAh/g) restricts the further improvement of LIBs. Fortunately, transition metal oxides (TMOs) demonstrate a several times higher capacity as compared to that of graphite because of the multiple electron reaction in conversion process [9]. The high theoretical capacity, high safety and huge abundance make the TMOs to be very promising anode materials [10].…”