Ni-rich layered oxides and Li-rich layered oxides are topics of much research interest as cathodes for Li-ion batteries due to their low cost and higher discharge capacities compared to those of LiCoO2 and LiMn2O4. However, Ni-rich layered oxides have several pitfalls, including difficulty in synthesizing a well-ordered material with all Ni3+ ions, poor cyclability, moisture sensitivity, a thermal runaway reaction, and formation of a harmful surface layer caused by side reactions with the electrolyte. Recent efforts towards Ni-rich layered oxides have centered on optimizing the composition and processing conditions to obtain controlled bulk and surface compositions to overcome the capacity fade. Li-rich layered oxides also have negative aspects, including oxygen loss from the lattice during first charge, a large first cycle irreversible capacity loss, poor rate capability, side reactions with the electrolyte, low tap density, and voltage decay during extended cycling. Recent work on Li-rich layered oxides has focused on understanding the surface and bulk structures and eliminating the undesirable properties. Followed by a brief introduction, an account of recent developments on the understanding and performance gains of Ni-rich and Li-rich layered oxide cathodes is provided, along with future research directions.

Nickel-Rich and Lithium-Rich Layered Oxide Cathodes: Progress and Perspectives

Surface coating of cathode materials has been widely investigated to enhance the life and rate capability of lithium-ion batteries. The surface coating discussed here was divided into three different configurations which are rough coating, core shell structure coating and ultra thin film coating. The mechanism of surface coating in achieving improved cathode performance and strategies to carry out this surface modification is discussed. An outlook on atomic layer deposition for lithium ion battery is also presented.

Role of surface coating on cathode materials for lithium-ion batteries

Cathode materials modified by surface coating for lithium ion batteries

Lithium metal is known to possess a very high theoretical capacity of 3,842 mAh g(-1) in lithium batteries. However, the use of metallic lithium leads to extensive dendritic growth that poses serious safety hazards. Hence, lithium metal has long been replaced by layered lithium metal oxide and phospho-olivine cathodes that offer safer performance over extended cycling, although significantly compromising on the achievable capacities. Here we report the defect-induced plating of metallic lithium within the interior of a porous graphene network. The network acts as a caged entrapment for lithium metal that prevents dendritic growth, facilitating extended cycling of the electrode. The plating of lithium metal within the interior of the porous graphene structure results in very high specific capacities in excess of 850 mAh g(-1). Extended testing for over 1,000 charge/discharge cycles indicates excellent reversibility and coulombic efficiencies above 99%.

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Defect-induced plating of lithium metal within porous graphene networks

An apparatus including a plurality of adjacent repeated base units, each base unit formed from an active electrode of first, second and third touch sensor arrays, the first, second and third touch sensor arrays each including a plurality of active electrodes connected to a respective common terminal of the touch sensor array, wherein each base unit includes an active electrode of the second touch sensor array interlaced between an active electrode of the first touch sensor array and an active electrode of the third touch sensor array such that a swipe touch gesture applied to two or more adjacent active electrodes of the apparatus generates signalling at the respective common terminals of the corresponding touch sensor arrays which allows the direction of the swipe touch gesture to be determined.

Apparatus and associated methods

A small planar elliptical dipole antenna designed for ultra-wideband applications is proposed. With trimmed elliptical radiation patches and microstrip-coupled feeding structure, it exhibits excellent broadband behaviours and radiation patterns similar to those of a conventional dipole antenna. The simulated and measured results are in good agreement.

Ultra-wideband microstrip-fed planar elliptical dipole antenna

Electrochemical evaluation and modification of commercial lithium cobalt oxide powders

Advanced triboelectric nanogenerator with multi-mode energy harvesting and anti-impact properties for smart glove and wearable e-textile

The influence of intralayer interfacial sliding among yarns on the enhancement of anti-impact and energy absorption was investigated in this work. Firstly, the rheological test and yarn pull-out test were conducted to analyze the relationship between the state of shear thickening fluid (STF) and the interfacial sliding among yarns. Then, the influence of impact velocity and constraint conditions on the interfacial sliding were studied by drop hammer and ballistic tests. The results showed that the impact speed and constraint conditions would affect the relative interfacial sliding rate among yarns, which would affected the rheological state of STF and the anti-impact performance of fabric. Besides, the mathematical model of the relationship between projectile velocity and fabric kinetic energy under the strong constraints was given by combining with the results of finite element analysis (FEA) of ballistic impact. This work provided a design idea for the body armor with high protective performance.

Junshuo Zhang

Papers

Ultra-wideband microstrip-fed planar elliptical dipole antenna

Electrochemical evaluation and modification of commercial lithium cobalt oxide powders

Advanced triboelectric nanogenerator with multi-mode energy harvesting and anti-impact properties for smart glove and wearable e-textile

Intralayer interfacial sliding effect on the anti-impact performance of STF/Kevlar composite fabric

Advanced functional Kevlar composite with excellent mechanical properties for thermal management and intelligent safeguarding