Li-ion batteries (LIBs) have become prevalent in modern day society, as they power cell phones, laptops, and electric vehicles (EV), among other items. Signifi cant research attention is focused on them in order to expand their use in the EV market and for possible deployment in grid storage applications for renewable power sources, such as wind, solar, and geothermal. One of the most explored areas of research in LIBs is designing 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 LiCoO 2 and LiMn 2 O 4 . However, Ni-rich layered oxides have several pitfalls, including diffi culty in synthesizing a well-ordered material with all Ni 3+ 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 fi rst charge, a large fi rst 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 Lirich layered oxide cathodes is provided, along with future research directions.LiNiO 2 has the α-NaFeO 2 structure with the oxide ions forming a cubic close-packed arrangement ( Figure 1 a). LiNiO 2 was fi rst

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While much research effort has been devoted to the development of advanced lithium-ion batteries for renewal energy storage applications, the sodium-ion battery is also of considerable interest because sodium is one of the most abundant elements in the Earth's crust. In this work, we report a sodium-ion battery based on a carbon-coated Fe3O4 anode, Na[Ni0.25Fe0.5Mn0.25]O2 layered cathode, and NaClO4 in fluoroethylene carbonate and ethyl methanesulfonate electrolyte. This unique battery system combines an intercalation cathode and a conversion anode, resulting in high capacity, high rate capability, thermal stability, and much improved cycle life. This performance suggests that our sodium-ion system is potentially promising power sources for promoting the substantial use of low-cost energy storage systems in the near future.

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This work reports the Li + uptake/extraction mechanism in silicon monoxide ͑SiO͒ as the negative electrode in lithium secondary batteries. A combined study of solid-state 29 Si-and 7 Li-nuclear magnetic resonance ͑NMR͒, electrochemical dilatometry, and charge-discharge cycling consistently demonstrates that the SiO 2 domain in SiO irreversibly reacts with Li + to produce lithium silicates and Li 2 O in the first discharging period, whereas the elemental Si domain reversibly reacts, delivering the same chargedischarge characteristics to those of conventional amorphous Si electrodes. The volume expansion accompanied by the irreversible reaction is less significant than that caused by the lithiation of Si domain. The postmortem analysis made on cycled electrodes reveals a phase segregation between the lithium silicates/Li 2 O and lithiated Si phase. It is likely that the lithium silicates/Li 2 O phase plays a buffering role against the volume change of Si matrix, but the crack formation at the phase boundaries and eventual pulverization are still a problem to be solved.

High-power, long-life carbon-coated TiO2 microsphere electrodes were synthesized by a hydrothermal method for sodium ion batteries, and the electrochemical properties were evaluated as a function of carbon content. The carbon coating, introduced by sucrose addition, had an effect of suppressing the growth of the TiO2 primary crystallites during calcination. The carbon coated TiO2 (sucrose 20 wt % coated) electrode exhibited excellent cycle retention during 50 cycles (100%) and superior rate capability up to a 30 C rate at room temperature. This cell delivered a high discharge capacity of 155 mAh g(composite)(-1) at 0.1 C, 149 mAh g(composite)(-1) at 1 C, and 82.7 mAh g(composite)(-1) at a 10 C rate, respectively.

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Delivery of high capacity with good retention is a challenge in developing cathodes for rechargeable sodium-ion batteries. Here we present a radially aligned hierarchical columnar With this cathode material, we show that an electrochemical reaction based on Ni 2 þ /3 þ /4 þ is readily available to deliver a discharge capacity of 157 mAh (g-oxide) À 1 (15 mA g À 1 ), a capacity retention of 80% (125 mAh g À 1 ) during 300 cycles in combination with a hard carbon anode, and a rate capability of 132.6 mAh g -1 (1,500 mA g -1 , 10 C-rate). The cathode also exhibits good temperature performance even at À 20°C. These results originate from rather unique chemistry of the cathode material, which enables the Ni redox reaction and minimizes the surface area contacting corrosive electrolyte.