Rational Construction of a Functionalized V₂O₅ Nanosphere/MWCNT Layer‐by‐Layer Nanoarchitecture as Cathode for Enhanced Performance of Lithium‐Ion Batteries

Abstract

5633wileyonlinelibrary.com a theoretical capacity of ≈294 mAh g −1 when the electrochemical window is in the range of 2-4 V, and possesses certain advantages over the common cathode materials, such as LiCoO 2 , LiMn 2 O 4 , LiFePO 4 , etc. [9][10][11][12][13] Moreover, cost effectiveness, facility of synthesis, and abundance in natural resource are other important advantages of investigatingV 2 O 5 cathode.Nevertheless, achieving decent electrochemical performances for V 2 O 5 in various aspects, including specifi c capacity, rate capability, and cycle life, has been a challenge which is ascribed to its low ionic diffusivity and inferior electrical conductivity. [ 9,[14][15][16] To address these intrinsic drawbacks, an effective strategy was adopted to decrease the active materials to nanoscale level, such as nanowires, [ 17 ] nanorods, [ 18 ] nanobelts, [ 19 ] and nanospheres, [ 20,21 ] which can shorten the transport lengths both for electrons and Li ions, minimize the effect of the low ionic diffusivity, and better accommodate the strain of Li ions intercalation/deintercalation in active materials. Moreover, these V 2 O 5 nanostructures were also integrated with conductive carbon nanostructures, such as carbon nanotube [ 22,23 ] and graphene, [ 14,24,25 ] which can not only further enhance the electrical conductivity of V 2 O 5 active material, but also help to prevent nanostructured V 2 O 5 active materials from agglomeration during cycling. Generally, the electrode is always prepared by mixing together active material, conductive agent, and polymer binder. Due to the nonuniform mixing process, some disadvantage voids can be found in the fi nal prepared electrode, and the active material can easily lose electrical contact with the conductive agent or metal current collector during cycling, resulting in incomplete electrochemical reaction and presenting capacity gradually fading. [ 26 ] Considering these disadvantages, the multiwalled carbon nanotubes (MWCNTs) with good electrical conductivity have been utilized to construct a binder-free layer-by-layer V 2 O 5 nanosphere (VOP)/MWCNT nanoarchitecture. In our proposed nanoarchitecture, the VOPs were modifi ed by positive charges and MWCNTs were terminated with negative charges. Then, we have stratifi ed the VOP and MWCNT layers from each other

Study of the Mechanisms of Internal Short Circuit in a Li/Li Cell by Synchrotron X-ray Phase Contrast Tomography

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] For example, the most promising Li metal-based battery technologies such as lithium-sulphur and lithium-air batteries have not been successfully commercialized mainly because of the uncontrolled growth of lithium microstructures (LmSs) such as dendrites, fibers, whiskers, moss, etc., which can cause internal short circuit (ISC) of a cell and result in catastrophic fires or even explosions. [15][16][17] Recent field incidents such as fires on a Boeing 787 Dreamliner flight and in a Tesla electric vehicle (EV) or even in the Samsung Note 7 smartphone are believed to be closely linked to ISCs in LIBs.…”

Carbon Nanotube Modified V2O5 Porous Microspheres as Cathodes for High‐Performance Lithium‐Ion Batteries

“…In the first cycle, the 3 evident cathodic peaks located at 3.33, 3.11, and 2.19 V indicate the multistep reduction process of V +5 in the V 2 O 5 lattice, and correspond to phase changes from α‐V 2 O 5 to ϵ‐Li 0.5 V 2 O 5 , then δ‐LiV 2 O 5 , and finally γ‐Li 2 V 2 O 5 , respectively. The oxidation peaks at 3.46, 3.38, and 2.22 V are attributed to the delithiation process . The reduction peaks at 3.33 and 3.11 V correspond to the following reactions: V 2 O 5 +0.5 Li + +0.5 e − =Li 0.5 V 2 O 5 , and Li 0.5 V 2 O 5 +0.5 Li + +0.5 e − =Li 1.0 V 2 O 5 .…”

“…The CNT shells with great electronic conductivity not only improve electron transportation and ion diffusion, but also enrich the available area for electrolyte access. Furthermore, the dispersed VCM particles can decrease the mean path of ions during the discharge/charge process …”

“…In particular, due to the easy accommodation of molecules or ions into its layers, V 2 O 5 can reach a theoretical capacity of about 294 mAh g −1 when 2 Li + ions intercalate into each V 2 O 5 layer . However, similarly to some metal oxides, the intrinsic low diffusion coefficient of lithium ions; poor electronic conductivity; and the irreversible structure corruption during cycling in crystalline V 2 O 5 , in particular, hinder the application of V 2 O 5 as a cathode for LIBs …”

Vanadium-oxide-based electrode materials for Li-ion batteries

“…[230] The composite electrode possessed a capacity of 140 mAh g cycle, realizing over 93% of the initial discharge capacity. [204] Poly(3,4-ethylenedioxythiophene) (PEDOT) is a popular conductive polymer with a high electrical conductivity (550 S cm…”