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.

In the previous paper Ralph Brodd and Martin Winter described the different kinds of batteries and fuel cells. In this paper I will describe lithium batteries in more detail, building an overall foundation for the papers that follow which describe specific components in some depth and usually with an emphasis on the materials behavior. The lithium battery industry is undergoing rapid expansion, now representing the largest segment of the portable battery industry and dominating the computer, cell phone, and camera power source industry. However, the present secondary batteries use expensive components, which are not in sufficient supply to allow the industry to grow at the same rate in the next decade. Moreover, the safety of the system is questionable for the large-scale batteries needed for hybrid electric vehicles (HEV). Another battery need is for a high-power system that can be used for power tools, where only the environmentally hazardous Ni/ Cd battery presently meets the requirements. A battery is a transducer that converts chemical energy into electrical energy and vice versa. It contains an anode, a cathode, and an electrolyte. The anode, in the case of a lithium battery, is the source of lithium ions. The cathode is the sink for the lithium ions and is chosen to optimize a number of parameters, discussed below. The electrolyte provides for the separation of ionic transport and electronic transport, and in a perfect battery the lithium ion transport number will be unity in the electrolyte. The cell potential is determined by the difference between the chemical potential of the lithium in the anode and cathode, ∆G ) -EF. As noted above, the lithium ions flow through the electrolyte whereas the electrons generated from the reaction, Li ) Li+ + e-, go through the external circuit to do work. Thus, the electrode system must allow for the flow of both lithium ions and electrons. That is, it must be both a good ionic conductor and an electronic conductor. As discussed below, many electrochemically active materials are not good electronic conductors, so it is necessary to add an electronically conductive material such as carbon * To whom correspondence should be addressed. Phone and fax: (607) 777-4623. E-mail: stanwhit@binghamton.edu. 4271 Chem. Rev. 2004, 104, 4271−4301

http://www.chemie.uni-regensburg.de/Anorganische_Chemie/Vortrag/StudentenWS06-07/Vortrag_Amereller.pdf

Lithium Batteries and Cathode Materials

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.

/pdf/electrochemical-energy-storage-for-green-grid-22ttg0wpz1.pdf

Electrochemical Energy Storage for Green Grid

The electrochemical behavior of Li/Li[Ni x Li (1/3-2x/3) Mn (2/3-x/3) ]O 2 cells for x = 1/b, 1/4, 1/3, 5/12, and 1/2 is reported. Li[Ni x Li (1/3-2x/3) Mn (2/3-x/3) ]O 2 is derived from Li 2 MnO 3 or Li[Li 1/3 Mn 2/3 ]O 2 by substitution of Li + and Mn 4+ by Ni 2+ while maintaining all the remaining Mn atoms in the 4+ oxidation state. Conventional wisdom suggests that lithium can be removed from these materials only until both the Ni and Mn oxidation states reach 4+, giving a charge capacity of 2x. We show that Li/Li[Ni x Li (1/3-2x/3) Mn (2/3-x/3) ]O 2 cells give smooth reversible voltage profiles reaching about 4.45 V when 2x Li atoms per formula unit are removed, as expected. If the cells are charged to higher voltages, surprisingly, they exhibit a long plateau of length approximately equal to I - 2x in the range between 4.5 and 4.7 V. Subsequent to this plateau, the materials can reversibly cycle over 225 mAh/g (almost one Li atom per formula unit) between 2.0 and 4.8 V. In situ X-ray diffraction and differential capacity measurements are used to infer that irreversible loss of oxygen from the compounds with x < 1/2 occurs during the first charge to 4.8 V. This results in oxygen deficient layered materials with stoichiometry approximately equal to [ ] X [Ni x Li (1-2x) Mn (2-x)/3 ]O 1.5+x at 4.8 V. These oxygen deficient materials then react reversibly with lithium.

https://iopscience.iop.org/article/10.1149/1.1480014/pdf

Understanding the Anomalous Capacity of Li / Li [ Ni x Li ( 1 / 3 − 2x / 3 ) Mn ( 2 / 3 − x / 3 ) ] O 2 Cells Using In Situ X-Ray Diffraction and Electrochemical Studies

The structure, synthesis, and electrochemical behavior of layered for 5/12, and 1/2 are reported for the first time. is derived from or by substitution of and by while maintaining all the remaining Mn atoms in the 4+ oxidation state. with can deliver steady capacities of 150 and 160 mAh/g at 30 and 55°C, respectively, between 3.0 and 4.4 V using a current density of 30 mA/g. Differential scanning calorimetry experiments on charged electrodes of for indicate that this material should be safer than with 5/12, and 1/2 can be cycled between 2.0 and 4.6 V to give capacities of about 200, 180, and 160 mAh/g, respectively, at 30°C. with gives a capacity of 220 mAh/g at 55°C between 2.0 and 4.6 V using a current density of 30 mA/g. © 2001 The Electrochemical Society. All rights reserved.

Layered Cathode Materials Li [ Ni x Li ( 1 / 3 − 2x / 3 ) Mn ( 2 / 3 − x / 3 ) ] O 2 for Lithium-Ion Batteries

The synthesis, structure, and electrochemical performance of Li[Ni x Li 1/3 2/3 Mn 2/3 3/3 ]O 2 for 0 < x ≤ 1/2 is presented. Li[Ni x Li 1/3 2x/3 Mn 2/3 x/3 ]O 2 is prepared by substituting Ni 2+ for Li' and Mn 4+ in Li[Li 1/3 Mn 2/3 ]O 2 while maintaining all the remaining Mn in the +4 oxidation state. Samples with x = 1/6, 1/4, 1/3, 5/12, and 1/2 have been investigated by X-ray diffraction (XRD) and neutron diffraction as well as by electrochemical measurements. The XRD and neutron diffraction patterns of Li[Ni x Li 1/3 2/3 Mn 2/3 x/3 ]O 2 (0 < x ≤ 1/2) show that these compounds adopt the O3-LiCoO 2 -type structure when synthesized at 800°C and higher. XRD and neutron diffraction also suggest a short-range superlattice ordering of Li, Ni, and Mn in the transition-metal layer for many of the samples. When synthesized at 700°C and lower, the compounds (for x = 1/3 and 1/2) appear to adopt a spinel-type structure like LT-LiCoO 2 , Electrochemical studies show that Li[Ni x Li 1/3 2x/3 Mn 2/3 x/3 ]O 2 (900°C) with x = 5/12 can deliver a stable capacity of about 160 mAh/g between 3.0 and 4.4 V vs. Li. An irreversible plateau is observed at about 4.5 V during the first charge of Li/Li[Ni x Li 1/3 2x/3 Mn 2/3 x/3 ]O 2 cells (x = 1/6, 1/4, 1/3, and 5/12), which we believe corresponds to the simultaneous removal of lithium and oxygen from the structure. After the plateau, Li[Ni x Li 1/3 2x/3 Mn 2/3 x/3 ]O 2 cells with x = 1/3 and 5/12 can deliver stable reversible capacities of about 230 and 225 mAh/g between 2.0 and 4.6 V. Li/Li[Ni x Li 1/3 2x/3 Mn 2/3 x/3 ]O 2 (0 < x ≤ 1/2) synthesized at low temperatures (i.e., 600 and 700°C) shows dramatically different differential capacity vs. voltage behavior compared to the high temperature samples, which must he related to the structural differences between materials prepared above and below 750°C.

Synthesis, Structure, and Electrochemical Behavior of Li [ Ni x Li1 / 3 − 2x / 3Mn2 / 3 − x / 3 ] O 2

https://iopscience.iop.org/article/10.1149/1.1413182/pdf

Zhonghua Lu

Papers

Understanding the Anomalous Capacity of Li / Li [ Ni x Li ( 1 / 3 − 2x / 3 ) Mn ( 2 / 3 − x / 3 ) ] O 2 Cells Using In Situ X-Ray Diffraction and Electrochemical Studies

Layered Cathode Materials Li [ Ni x Li ( 1 / 3 − 2x / 3 ) Mn ( 2 / 3 − x / 3 ) ] O 2 for Lithium-Ion Batteries

Synthesis, Structure, and Electrochemical Behavior of Li [ Ni x Li1 / 3 − 2x / 3Mn2 / 3 − x / 3 ] O 2

Layered Li [ NixCo1 − 2xMnx ] O 2 Cathode Materials for Lithium-Ion Batteries

A comparison of the electrode/electrolyte reaction at elevated temperatures for various Li-ion battery cathodes