The challenges for further development of Li rechargeable batteries for electric vehicles are reviewed. Most important is safety, which requires development of a nonflammable electrolyte with either a larger window between its lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) or a constituent (or additive) that can develop rapidly a solid/ electrolyte-interface (SEI) layer to prevent plating of Li on a carbon anode during a fast charge of the battery. A high Li-ion conductivity (σ Li > 10 ―4 S/cm) in the electrolyte and across the electrode/ electrolyte interface is needed for a power battery. Important also is an increase in the density of the stored energy, which is the product of the voltage and capacity of reversible Li insertion/extraction into/from the electrodes. It will be difficult to design a better anode than carbon, but carbon requires formation of an SEI layer, which involves an irreversible capacity loss. The design of a cathode composed of environmentally benign, low-cost materials that has its electrochemical potential μ C well-matched to the HOMO of the electrolyte and allows access to two Li atoms per transition-metal cation would increase the energy density, but it is a daunting challenge. Two redox couples can be accessed where the cation redox couples are "pinned" at the top of the O 2p bands, but to take advantage of this possibility, it must be realized in a framework structure that can accept more than one Li atom per transition-metal cation. Moreover, such a situation represents an intrinsic voltage limit of the cathode, and matching this limit to the HOMO of the electrolyte requires the ability to tune the intrinsic voltage limit. Finally, the chemical compatibility in the battery must allow a long service life.

Challenges for Rechargeable Li Batteries

Each cell of a battery stores electrical energy as chemical energy in two electrodes, a reductant (anode) and an oxidant (cathode), separated by an electrolyte that transfers the ionic component of the chemical reaction inside the cell and forces the electronic component outside the battery. The output on discharge is an external electronic current I at a voltage V for a time Δt. The chemical reaction of a rechargeable battery must be reversible on the application of a charging I and V. Critical parameters of a rechargeable battery are safety, density of energy that can be stored at a specific power input and retrieved at a specific power output, cycle and shelf life, storage efficiency, and cost of fabrication. Conventional ambient-temperature rechargeable batteries have solid electrodes and a liquid electrolyte. The positive electrode (cathode) consists of a host framework into which the mobile (working) cation is inserted reversibly over a finite solid–solution range. The solid–solution range, which is...

The Li-ion rechargeable battery: a perspective.

Energy storage using batteries offers a solution to the intermittent nature of energy production from renewable sources; however, such technology must be sustainable. This Review discusses battery development from a sustainability perspective, considering the energy and environmental costs of state-of-the-art Li-ion batteries and the design of new systems beyond Li-ion. Images: batteries, car, globe: © iStock/Thinkstock.

Towards greener and more sustainable batteries for electrical energy storage

Research Development on Sodium-Ion Batteries

The is a comprehensive review on the needs and potential storage technologies for electrical grid that is expected to integrate significant levels of renewables. This review offers details of the technologies, in terms of needs, status, challenges and future R&d directions.

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Electrochemical Energy Storage for Green Grid

Fast Na+-ion transport in skeleton structures

Crystal structure of potassium neodymium metaphosphate, KNdP4O12, a new acentric laser material☆

The evolution with $x$ of the monoclinic-to-tetragonal transition temperature and of the room-temperature monoclinic structures of the system ${\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{2}$ have been reexamined and extended to cover the entire solid-solution range $0\ensuremath{\le}xl0.20$. The space group of the room-temperature monoclinic phase changes from $\frac{P{2}_{1}}{c}$ at $x=0$ to $\frac{C2}{m}$ for $0.005\ensuremath{\le}x\ensuremath{\le}0.065$ and $\frac{P2}{m}$ for $0.07\ensuremath{\le}xl0.20$. The monoclinic $\frac{P2}{m}$ structure is determined for the first time. The distortion from tetragonal symmetry is accomplished by a contraction of the V-O bonds in the tetragonal ${(110)}_{r}$ planes and an expansion in the ${(1\overline{1}0)}_{r}$ planes. The structures and the conductivity changes are interpreted in terms of two overlapping bands that change their relative stabilities with $x$. The substitutional ${\mathrm{Cr}}^{3+}$ ions, which have a localized-electron ${d}^{3}$ configuration, also perturb the electron potential sufficiently to induce, at larger $x$, a $3d$-electron localization on the vanadium ions.

Structures and a Two-Band Model for the System V 1-x Cr x O 2

Crystal chemistry in the system MSbO3

Fast alkali-metal-ion transporters are provided having low resistivities and low-activation-energy mobilities at temperatures at which alkali metals are molten. The novel compounds promote alkali-metal-ion transport in three dimensions within their crystalline structure and have the general formula: A.sub.n X.sub.2 (ZO.sub.4).sub.3 or A.sub.m (Z'.sub.2 O.sub.4) wherein A is potassium, sodium or lithium, Z' is a tetrahedrally coordinated cation or mixtures thereof, X is an octahedrally coordinated cation or mixtures thereof, n is a number greater than 1 and less than 4, m is a number from 1 up to 2 and Z' is a mixture of at least two Z' cations. BACKGROUND OF THE INVENTION

Henry Y-P Hong

Papers

Fast Na+-ion transport in skeleton structures

Crystal structure of potassium neodymium metaphosphate, KNdP4O12, a new acentric laser material☆

Structures and a Two-Band Model for the System V 1-x Cr x O 2

Crystal chemistry in the system MSbO3

Compositions for fast alkali-metal-ion transport