MnO₂ Nanosheets on a Carbon Nanofiber Freestanding Film by Electrospinning and In Situ Spraying for Lithium and Sodium Storage

Abstract

Freestanding electrodes are critical for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) with high energy density and long cycling stability. We fabricated freestanding MnO2 nanosheet-coated carbon nanofibers by synchronous in situ spraying of MnO2 nanosheets onto electrospinning polymer nanofibers, which might be a high-voltage electric field-induced assembly process. The designed film is used as anode material for LIBs and SIBs. It demonstrates good cycling stability without capacity loss after long cycling for LIBs, delivers a capacity of 256.4 mAh g–1 at 1.00 A g–1, and has an extremely stable cycle life for over 200 cycles at 0.05 A g–1. For SIBs, it delivers a capacity of 135.0 mAh g–1 at 1.00 A g–1 and has a stable cycle life for over 500 cycles at 0.50 A g–1. The capacitive contribution ratio increases from 44.4 to 76.2% (0.2–1.0 mV s–1), and the capacitive process plays a major role in the total capacity. The enhancement of the electrochemical performance is attributed to the good conductivity of the carbon nanofiber network and the one-dimensional (1D)/two-dimensional (2D) composite structure of the electrode, in which the high performance of carbon nanofibers and MnO2 nanosheets is fully exploited. Importantly, the combination of in situ spraying and electrospinning can be extended to two or more materials with different polarities, ζ-potential values, or solubilities, broadening the applications of composites.

Synthesis of a (NiFe)9S8 nanorod array as a negative electrode for a high-performance hybrid supercapacitor

“…The battery-type capacitance accounted for 68% at a sweep rate of 5 mV s −1 , and the proportion of the diffusion-controlled capacitance gradually decreased as the sweep rate increased, to 25% at 50 mV s −1 . 47,48…”

Review of low‐temperature lithium‐ion battery progress: New battery system design imperative

“…Therefore, carbonaceous doping alloy‐based materials are good candidates for low‐temperature LIB anodes, as well as other materials with maximum theoretical capacities 45 such as CeVO 4, 48 Co 0.85 Se, 49 MnO 2, 45 CuSi 2 P 3, 50 Fe 2 O 3, 51 Mn 3 O 4, 52 Cu 2 WS 4, 53 Cu 2 O, 54 Li 3 VO 4, 55 Co 3 O 4, 56 NiO nanocrystals, nano‐Mn 2 O 3 particles, 57 MoS 2, 58,59 and MoSe 2 37 and SiO 2 . After carbonaceous doping, the low‐temperature characteristics could increase, which could be due to a stable SEI sheet 64‐71 . Nobili et al 59 used tin/graphite as the anode and applied it at −20°C (0.2 C, 1 mol/L LiPF 6 EC‐DEC‐DMC 1:1:1 as the electrolyte), the SEI resistance and Rct were lowered by 3 and 10 times, respectively, compared to the undoped material.…”

“…After carbonaceous doping, the low-temperature characteristics could increase, which could be due to a stable SEI sheet. [64][65][66][67][68][69][70][71] Nobili et al 59 used tin/graphite as the anode and applied it at À20 C (0.2 C, 1 mol/L LiPF 6 EC-DEC-DMC 1:1:1 as the electrolyte), the SEI resistance and Rct were lowered by 3 and 10 times, respectively, compared to the undoped material. Li et al found that Fe-added Fe 3 C carbon nanofibers as an anode result in a better low-temperature performance of LIBs.…”

Synergistic effect of 1D bismuth Nanowires/2D graphene composites for high performance flexible anodes in sodium-ion batteries

“…27,28 With the growing demand for wearable electronic devices for exible energy storage systems, a exible electrode with high energy density is of great importance for future application. Flexible electrodes are usually made from the methodologies of embedding the active materials in exible carbon nanobers, [29][30][31] growing them on exible conductive substrates, 32,33 and compositing them with two dimensional (2D) nanosheets, 34,35 which not only have good exibility, but can also provide higher energy density by avoiding the usage of an inactive binder and current collector compared to the traditional electrodes prepared via the slurry-coating method. [36][37][38] Graphene has proven to be a typical 2D carbon material with superior conductivity and large surface area.…”