Approaching High‐Performance Lithium Storage Materials by Constructing Hierarchical CoNiO₂@CeO₂ Nanosheets

Abstract

Rechargeable Li-ion batteries (LIBs) with nonaqueous electrolytes that employ graphite as an anode active material have been used for electric vehicle recently. However, these lithium storage devices have been subject to safety issue, which arise from short circuit during fast charging and discharging process. [1][2][3] This issue generally ascribes to the low intercalation voltage plateau of graphite at about 0 V (vs Li/Li + ), which might generate lithium dendrites on it. [4,5] Thus, it is urgent to exploit appropriate anode materials to cut down the dependence over graphite. Transition metal oxides (TMOs), especially cobalt oxide and nickel oxide, such as NiO, CoO, and Co 3 O 4 are deemed as the most competitive substitutes for graphite in battery industry due to its high-reversible capacity, good safety, and high power density. [6][7][8][9][10][11] However, monometal oxides suffer from low coulombic efficiencies in initial charge-discharge process, unfixed SEI film, large voltage hysteresis, and inferior cycling ability. [12] Nevertheless, these weaknesses could be improved by introducing different cations because bimetallic oxide reveals better electrochemical activities and higher electrical conductivities than monometal oxides. [13] Hence, nickel-cobalt mixed-metal oxides, such as NiCo 2 O 4 and CoNiO 2 , have received a wide range of attention from all over the world as electrode materials for LIB. [14][15][16][17] Among them, NiCo 2 O 4 gained tremendous attention because of its large theoretical capacity (890 mA h g −1 ) and excellent electron conductivity than their monometal counterpart. [18] But recent researches revealed that NiCo 2 O 4 possessed irreversible electrochemical reaction and therefore its outstanding electron conductivity might not exist any longer. [19,20] But on the other hand, another nickel-cobalt oxide, CoNiO 2 can be a brilliant choice due to its high-reversibility, high capacity and moderate volume expansion. But CoNiO 2 ineluctably undergo several primary issues: volume changes during charge-discharge processes, pulverization, and aggregation of pristine electrode materials and low electronic conductivity on account of its inherent conversion-type lithium storage mechanism and intrinsic semi-conducting nature. All these issues impede the speed and completeness of conversion reaction and then result in poor cycling ability and rate performance. To surmount these limitations, one viable way is to construct and prepare advanced electrode with favorable morphology and reasonable composition. Specially, hierarchical structures, which are constituted by elementary building unit (e.g., nanoparticles, nanowires, and nanosheets) with a porous peculiarity, have appealed to many researchers. [21][22][23] This is because such hierarchical structures succeed to elementary building units as well as benefits on account of the synergistic effects between

Modulating Crystal and Interfacial Properties by W‐Gradient Doping for Highly Stable and Long Life Li‐Rich Layered Cathodes

“…To have an overall description of the architecture of W@LLMO, the Mn, Ni, and Co contents within W@LLMO are also described. [ 23 ] Being opposite to that of W 5+ and W 6+ (Figure 2a, Table 2), the peaks of Mn 2p gradually shift to the high energy direction with the increase of ET, indicating the gradual increase in Mn valence (Figure 2b). Consistently, the amount of Mn 3+ decreases gradually from surface to bulk as the ET increases.…”

Enhancing the Cycling Stability for Lithium-Metal Batteries by Localized High-Concentration Electrolytes with 2-Fluoropyridine Additive

“…Notably, compared with that of LHCE, the R f of LHCE + 2-FP is smaller, which indicates that the positive influence of 2-FP on the interface is beneficial for the easier migration of Li + in SEI. Meanwhile, LHCE-2-FP (16.93/38.74 Ω) shows lower R s / R ct value than LHCE (15.57/45.44 Ω), which reflects that the products of 2-FP reduce the electronic conductivity, resulting in a stable SEI film. − …”

Templated synthesis of 2D TiO2 nanoflakes for durable lithium ion batteries

“…4c, O exists in the form of Ti–O and C–O bonds, which emerge at 530.3 and 531.8 eV, respectively. 22 The existence of C–O bonds can well explain the existence of Ti 3+ in Ti 2p. Moreover, Fig.…”