Search

Aiming for increased nickel and lower cobalt content in layered transition metal oxide cathodes (NCM) is a feasible strategy for achieving increased energy density and cost competitiveness in commercial lithium‐ion batteries. However, the practical long‐term cycling of NCM cathodes suffers from severe capacity degradation due to irreversible interface phase transformation and unavoidable crack formation. Herein, an in situ modification strategy is used to form a uniform and conformal Li1.8Sc0.8Ti1.2(PO4)3 (LSTP) protective layer by interconnecting the single‐crystal‐layered LiNi0.6Co0.1Mn0.3O2 (SC‐NCM) particles. LSTP surface modification helps to construct a robust cathode‐electrolyte interphase thin film between the cathode and the electrolyte, which can prevent SC‐NCM corrosion by electrolyte, and the stability of the mechanics can improve the intergranular cracks caused by long cycles under harsh conditions. Moreover, the LSTP conductive modification layer facilitates the lithium‐ion transport among cathode particles, effectively enhancing the rate capability. Impressively, the LSTP modified SC‐NCM exhibits a high reversible capacity of 144.3 mAh g−1 at the high discharge rate of 5 C and maintains a capacity retention of 90.27% even at the ultrahigh charge voltage of 4.6 V operation after 500 cycles. Moreover, in a pouch‐type full battery, the graphite/LSTP modified SC‐NCM maintains a capacity retention of 89.6% after 1700 cycles. [ABSTRACT FROM AUTHOR]

Although sodium-ion batteries (SIBs) are considered as alternatives to lithium-ion batteries (LIBs), the electrochemical performances, in particular the energy density, are much lower than LIBs. A metal-organic compound, cuprous 7,7,8,8-tetracyanoquinodimethane (CuTCNQ), is presented as a new kind of cathode material for SIBs. It consists of both cationic (CuII↔CuI) and anionic (TCNQ0↔TCNQ−↔ TCNQ2−) reversible redox reactions, delivering a discharge capacity as high as 255 mAh g−1 at a current density of 20 mA g−1. The synergistic effect of both redox-active metal cations and organic anions brings an electrochemical transfer of multiple electrons. The transformation of cupric ions to cuprous ions occurs at near 3.80 V vs. Na+/Na, while the full reduction of TCNQ0 to TCNQ− happens at 3.00-3.30 V. The remarkably high voltage is attributed to the strong inductive effect of the four cyano groups. [ABSTRACT FROM AUTHOR]

Although sodium-ion batteries (SIBs) are considered as alternatives to lithium-ion batteries (LIBs), the electrochemical performances, in particular the energy density, are much lower than LIBs. A metal-organic compound, cuprous 7,7,8,8-tetracyanoquinodimethane (CuTCNQ), is presented as a new kind of cathode material for SIBs. It consists of both cationic (CuII↔CuI) and anionic (TCNQ0↔TCNQ−↔ TCNQ2−) reversible redox reactions, delivering a discharge capacity as high as 255 mAh g−1 at a current density of 20 mA g−1. The synergistic effect of both redox-active metal cations and organic anions brings an electrochemical transfer of multiple electrons. The transformation of cupric ions to cuprous ions occurs at near 3.80 V vs. Na+/Na, while the full reduction of TCNQ0 to TCNQ− happens at 3.00-3.30 V. The remarkably high voltage is attributed to the strong inductive effect of the four cyano groups. [ABSTRACT FROM AUTHOR]

Tin-based oxide Li2SnO3 has been synthesized by a hydrothermal route as negative material for lithium-ion batteries. The microstructure and electrochemical properties of the as-synthesized materials were investigated by some characterizations means and electrochemical measurements. The as-synthesized Li2SnO3 is a porous rod, which is composed of many uniform and regular nano-flakes with a size of 50-60 nm. Li2SnO3 also displays an electrochemical performance with high capacity and good cycling stability (510.2 mAh g−1 after 50 cycles at a current density of 60 mA g−1 between 0.0 V and 2.0 V verusus Li/Li+). Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A graphene-supported Ce- SnS2 ( Ce- SnS2/graphene) nanocomposite has been synthesized via a hydrothermal route. Structure, morphology, and electrochemical properties of the composites were studied by means of XRD, SEM, TEM, Raman, XPS, TGA, and electrochemical measurements. The Ce- SnS2 crystal particles with a flower-like structure were distributed on the graphene sheets ( GNS). The particle sizes of each petal are in the range 50-100 nm with clear lattice fringes. The atomic ratio of Sn, S, Ce, C, and O is estimated to be 1:2:0.05:3.11:0.64 and the content of Ce- SnS2 composite is 80 wt.% in the as-synthesized sample. The Ce- SnS2/graphene composite exhibits high initial discharge capacity (1638.3 mAh/g at 0.5 C), high capacity retention (707 mAh/g at 0.5 C after 50 cycles), and good rate capability due to the synergy effect between Ce- SnS2 nanoparticles and graphene nanosheets. The superior performance is ascribed to the presence of graphene keeping the structure stable. [ABSTRACT FROM AUTHOR]

Anionic redox activity can trigger structural instability in Li‐rich Mn‐based cathodes. Lattice oxygen activity can be tuned through liquid acid‐induced spinel phases and oxygen vacancies. However, the liquid‐acid‐modified surface is still attacked by the electrolyte. Besides, the underlying mechanism of spinel phase suppression of lattice oxygen activity is controversial. Here, a solid acid strategy for modification is proposed and the underlying mechanism is investigated in detail. Unique solid acid can in situ generate an interface protection layer and remarkably stabilize the structure. Theoretical calculations and experimental characterizations reveal that the spinel phase suppresses the irreversible loss of lattice oxygen by decreasing the O 2p non‐bonding energy level and enriching electrons at the layered/spinel phase interface. The inert layer on the surface prevents highly active On− from being attacked by electrolytes. The obtained material exhibits significantly reduced irreversible lattice oxygen release and improved electrochemical performance. After 300 cycles, a slow capacity fading of 0.177 mAh g−1 per cycle and suppressed voltage fading are achieved. This study reveals the regulation method and mechanism for the anion activity of oxide cathodes in next‐generation Li‐ion batteries. [ABSTRACT FROM AUTHOR]