Rechargeable sodium-ion batteries have drawn increasing attention as candidates for the post lithium-ion batteries in large-scale energy storage systems. Layered oxides are the most promising cathode materials and their pure phases (e.g., P2, O3) have been widely investigated. Here we report a series of cathode materials with O3/P2 hybrid phase for sodium-ion batteries, which possesses advantages of both P2 and O3 structures. The designed material, NaNiFeMnO, can deliver a capacity of 86 mAh g with great rate capability and cycling performance. 66% capacity is still maintained when the current rate reaches as high as 10C, and the capacity retention is 90% after 1500 cycles. Moreover, in situ XRD was performed to examine the structure change during electrochemical testing in different voltage ranges, and the results demonstrate 4 V as the optimized upper voltage limit, with which smaller polarization, better structural stability, and better cycling performance are achieved. The results obtained here provide new insights in designing cathode materials with optimal structure and improved performance for sodium-ion batteries.

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk

We have fabricated an all‐polymer battery utilizing the redox properties of electrically conducting polymers for the anode and cathode in conjunction with an ionic conducting polymer gel electrolyte. The anode and cathode consist of pyrrole electropolymerized onto a graphite fiber substrate resulting in a high‐surface‐area, composite electrode. A polymer gel electrolyte, based on polyacrylonitrile, was solution cast onto the electrodes to form an all‐polymer cell. This system exhibits a specific charge capacity of 22 mAh g−1 based on the electroactive mass of the cathode and discharging the system to 0.4 V. These cells show no loss of capacity when cycled to 100 cycles.

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. I. INTRODUCTIONHE more-electric aircraft (MEA) concept is one of the major trends in modern aerospace engineering aiming for reduction of the overall aircraft weight, operation cost and environmental impact. Electrical systems are employed to replace existing hydraulic, pneumatic and mechanical actuators. As a consequence, the onboard installed electrical power increases significantly and this results in challenges in the design of the aircraft electrical power systems (EPS). The tendency is to replace traditional AC distribution with highvoltage DC distribution. This can increase efficiency, reduce weight and remove the need for reactive power compensation devices [1], [2].In literature, the primary power distribution in aircrafts has been traditionally based on the single-generator-per-bus paradigm with switched distribution providing the connectivity and system integrity. Instead, the proposed "single-bus" concept uses the micro-grid approach in which all the generators and loads are connected to a single distribution bus. This single bus configuration has been widely used in other applications such as residential microgrids [3]. Such a system has the potential to considerably reduce the EPS weight since bus mass is reduced and load and generator fault isolation function can be integrated in power converters; in addition the controlled power sharing between generators has the potential to reduce generator capacity and operate at maximum efficiency levels.As the parallel operation of multiple generators is a promising solution for the MEA EPS, appropriate power sharing among the different power sources needs to be carefully considered. From the communication point of view, overall control of DC systems can be divided into three categories: distributed control, centralized control and decentralized control [4].

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk 1 Abstract-This paper proposes an improved voltage regulation method in multi-source based DC electrical power system in the more electric aircraft. The proposed approach, which can be used in terrestrial DC microgrids as well, effectively improves the load sharing accuracy under high droop gain circumstance with consideration of cable impedance. Since no extra communication line and controllers are required, it is easily implemented and also increases the system modularity and reliability. By using the proposed approach the DC transmission losses can be reduced and system stability is not deteriorated for normal and fault scenarios. In this paper optimal droop gain settings are investigated and the selection of individual droop gains as well as the proportional power sharing ratio has been described. Experimental results validate the effectiveness of the proposed method.Index Terms-DC power system, droop control, load sharing, voltage deviation, transmission losses.

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High-energy–density lithium-ion batteries (LIBs) that can be safely fast-charged are desirable for electric vehicles. However, sub-optimal lithiation potential and low capacity of commonly used LIBs anode cause safety issues and low energy density. Here we hypothesize that a cobalt vanadate oxide, Co2VO4, can be attractive anode material for fast-charging LIBs due to its high capacity (~ 1000 mAh g−1) and safe lithiation potential (~ 0.65 V vs. Li+/Li). The Li+ diffusion coefficient of Co2VO4 is evaluated by theoretical calculation to be as high as 3.15 × 10–10 cm2 s−1, proving Co2VO4 a promising anode in fast-charging LIBs. A hexagonal porous Co2VO4 nanodisk (PCVO ND) structure is designed accordingly, featuring a high specific surface area of 74.57 m2 g−1 and numerous pores with a pore size of 14 nm. This unique structure succeeds in enhancing Li+ and electron transfer, leading to superior fast-charging performance than current commercial anodes. As a result, the PCVO ND shows a high initial reversible capacity of 911.0 mAh g−1 at 0.4 C, excellent fast-charging capacity (344.3 mAh g−1 at 10 C for 1000 cycles), outstanding long-term cycling stability (only 0.024% capacity loss per cycle at 10 C for 1000 cycles), confirming the commercial feasibility of PCVO ND in fast-charging LIBs.

Sodium-ion batteries (SIBs) are promising candidates for largescale energy storage systems due to the abundance and wide distribution of sodium resources. Various solutions have been successfully applied to revolve the large-ionsize-induced battery issues at the mid-to-low current density range. However, the fast-charging properties of SIBs are still in high demand to accommodate the increasing energy needs at large to grid scales. Herein, a core−shell Co 2 VO 4 / carbon composite anode is designed to tackle the fast-charging problem of SIBs. The synergetic effect from the stable spinel structure of Co 2 VO 4 , the size of the nanospheres, and the carbon shell provide enhanced Na + ion diffusion and electron transfer rates and outstanding electrochemical performance. With an ultrahigh current density of 5 A g −1 , the Co 2 VO 4 @C anode achieved a capacity of 135.1 mAh g −1 and a >98% capacity retention after 2000 cycles through a pseudocapacitive dominant process. This study provides insights for SIB fastcharging material design and other battery systems such as lithium-ion batteries.