Spinel LiNi 0.45 Cr 0.1 Mn 1.45 O 4 synthesized by a scalable solution route combined by high temperature calcination is investigated as cathode for ultralong-life lithium-ion batteries in a wide operating temperature range. Scanning electron microscopy reveals homogeneous microsized polyhedral morphology with highly exposed {100} and {111} surfaces. The most highlighted result is that LiNi 0.45 Cr 0.1 Mn 1.45 O 4 has extremely long cycle performance and high capacity retention at various temperatures (0, 25, 50 °C), indicating that Cr doping is a prospective approach to enable 5 V LiNi 0.5 Mn 1.5 O 4 (LNMO)-based cathode materials with excellent cycling performances for commercial applications. After 1000 cycles, the capacity retention of LiNi 0.45 Cr 0.1 Mn 1.45 O 4 is 100.30% and 82.75% at 0 °C and 25 °C at 1 C rate, respectively. Notably, over 350 cycles at 50 °C, the capacity retention of LiNi 0.45 Cr 0.1 Mn 1.45 O 4 can maintain up to 91.49% at 1 C. All the values are comparable to pristine LNMO, which can be attributed to the elimination of Li y Ni 1−y O impurity phase, highly exposed {100} surfaces, less Mn 3+ ions, and enhancement of ion and electron conductivity by Cr doping. Furthermore, an assembled LiNi 0.45 Cr 0.1 Mn 1.45 O 4 /Li 4 Ti 5 O 12 full cell delivers an initial discharge capacity of 101 mA h g −1 , meanwhile the capacity retention is 82.07% after 100 cycles.
The silicon anode holds great potential for next-generation lithium-ion batteries in view of its high gravimetric capacity and natural abundance. The main challenges associated with silicon are the structural degradation and instability caused by huge volume change upon cycling. We report herein polybenzimidazole (PBI) derived pyrrolic N-enriched carbon as an ideal encapsulation onto microsized silicon spheres, which is achieved by an aerosol-assisted assembly combined with a simple physisorption process. The new polymer derived carbon endows silicon with the structural and compositional characteristics of intrinsic high electronic conductivity, abundant pyrrolic nitrogen, and structure robustness. The resulting mesoporous Si-PBI carbon composite exhibits excellent lithium storage performance in terms of high reversible specific capacity of 2172 mAh g −1 , superior rate capability (1186 mAh g −1 at 5 A g −1 ), and prolonged cycling life. As a result, a fabricated Si/LiCoO 2 full battery demonstrates high energy density of 367 Wh kg −1 as well as good cycling stability for 100 cycles.
Supercapacitors, as a type of energy storage system, bridge the power/energy gap between conventional capacitors and batteries due to attractive properties such as high power density, long cycle lifespan, and large temperature range. However, the low energy density of supercapacitors compared to lithium‐ion batteries has hindered their general application. In general, the electrochemical performance of supercapacitors is closely related to the structure of their electrode materials, electrolytes, and device design. The main materials used in electrochemical double‐layer capacitors (EDLCs) are carbon materials with various architectures. This is due to their high surface area, good electric conductivity, and intrinsic stability. In this review, recently reported carbon‐based nanostructured electrode materials with 0D, 1D, 2D, and 3D structures are systematically reviewed. The effect of nanostructuring on the properties of supercapacitors including specific capacitance, rate capability, and cycle stability is explored, the details of which may serve as a guide to electrode design for the next generation of EDLCs.
Aqueous sodium‐ion capacitors (ASICs) are becoming increasingly important due to the remarkable advantages of aqueous electrolyte about the excellent ionic conductivity, non‐flammability and low cost compared with organic systems. But, low capacitance of the electric double‐layer capacitive material and narrow potential window of aqueous electrolyte both have negative effects on the enhancement of energy density. Therefore, we employ typical pseudocapacitive material, layered MnO2/CNTs composite as cathode to fabricate sodium ion capacitor. It needs to be emphasized that the electrochemical process involves two kinds of energy storage mechanisms, such as the reversible Na+ adsorption/desorption onto the surface of each layer and fast Na+ (de)intercalation into the 2D interlayer space. Thus, the composite delivers a high specific capacitance (322.5 F g−1 at 0.5 A g−1) and an excellent cycle stability (5000 cycles with capacitance retention of approximately 90 %). By means of the synergistic effects of the layered MnO2/CNTs cathode, sodium‐ion water‐in‐salt electrolyte (NaWiSE) and polyimide organic anode, the as‐assembled ASIC achieves a high energy density of 78.5 Wh kg−1, accompanied by high power density of 11000 W kg−1 and excellent cycle performance (even 77 % capacity retention after 10000 cycles).
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