Electrolytes and interphases in Li-ion batteries and beyond.

Energy density is the main property of rechargeable batteries that has driven the entire technology forward in past decades. Lithium-ion batteries (LIBs) now surpass other, previously competitive battery types (for example, lead–acid and nickel metal hydride) but still require extensive further improvement to, in particular, extend the operation hours of mobile IT devices and the driving mileages of all-electric vehicles. In this Review, we present a critical overview of a wide range of post-LIB materials and systems that could have a pivotal role in meeting such demands. We divide battery systems into two categories: near-term and long-term technologies. To provide a realistic and balanced perspective, we describe the operating principles and remaining issues of each post-LIB technology, and also evaluate these materials under commercial cell configurations. Post-lithium-ion batteries are reviewed with a focus on their operating principles, advantages and the challenges that they face. The volumetric energy density of each battery is examined using a commercial pouch-cell configuration to evaluate its practical significance and identify appropriate research directions.

Promise and reality of post-lithium-ion batteries with high energy densities

Over the past 30 years, significant commercial and academic progress has been made on Li-based battery technologies. From the early Li-metal anode iterations to the current commercial Li-ion batteries (LIBs), the story of the Li-based battery is full of breakthroughs and back tracing steps. This review will discuss the main roles of material science in the development of LIBs. As LIB research progresses and the materials of interest change, different emphases on the different subdisciplines of material science are placed. Early works on LIBs focus more on solid state physics whereas near the end of the 20th century, researchers began to focus more on the morphological aspects (surface coating, porosity, size, and shape) of electrode materials. While it is easy to point out which specific cathode and anode materials are currently good candidates for the next-generation of batteries, it is difficult to explain exactly why those are chosen. In this review, for the reader a complete developmental story of LIB should be clearly drawn, along with an explanation of the reasons responsible for the various technological shifts. The review will end with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.

30 Years of Lithium-Ion Batteries.

Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

A review of electrolyte materials and compositions for electrochemical supercapacitors

Electrical energy storage (EES) is one of the most critical areas of technological research around the world. Storing and efficiently using electricity generated by intermittent sources and the transition of our transportation fleet to electric drive depend fundamentally on the development of EES systems with high energy and power densities. Supercapacitors are promising devices for highly efficient energy storage and power management, yet they still suffer from moderate energy densities compared to batteries. To establish a detailed understanding of the science and technology of carbon/carbon supercapacitors, this review discusses the basic principles of the electrical double-layer (EDL), especially regarding the correlation between ion size/ion solvation and the pore size of porous carbon electrodes. We summarize the key aspects of various carbon materials synthesized for use in supercapacitors. With the objective of improving the energy density, the last two sections are dedicated to strategies to increase the capacitance by either introducing pseudocapacitive materials or by using novel electrolytes that allow to increasing the cell voltage. In particular, advances in ionic liquids, but also in the field of organic electrolytes, are discussed and electrode mass balancing is expanded because of its importance to create higher performance asymmetric electrochemical capacitors.

Carbons and Electrolytes for Advanced Supercapacitors

A programmable metallization cell ("PMC") comprises a fast ion conductor such as a chalcogenide-metal ion and a plurality of electrodes (e.g., an anode and a cathode) disposed at the surface of the fast ion conductor and spaced a set distance apart from each other. Preferably, the fast ion conductor comprises a chalcogenide with Group IB or Group IIB metals, the anode comprises silver, and the cathode comprises aluminum or other conductor. When a voltage is applied to the anode and the cathode, a non-volatile metal dendrite grows from the cathode along the surface of the fast ion conductor towards the anode. The growth rate of the dendrite is a function of the applied voltage and time. The growth of the dendrite may be stopped by removing the voltage and the dendrite may be retracted by reversing the voltage polarity at the anode and cathode. Changes in the length of the dendrite affect the resistance and capacitance of the PMC. The PMC may be incorporated into a variety of technologies such as memory devices, programmable resistor/capacitor devices, optical devices, sensors, and the like. Electrodes additional to the cathode and anode can be provided to serve as outputs or additional outputs of the devices in sensing electrical characteristics which are dependent upon the extent of the dendrite.

Programmable metallization cell structure and method of making same

A programmable sub-surface aggregating metallization structure (100) includes an ion conductor (110) such as a chalcogenide glass which includes metal ions and at least two electrodes (120, 130) disposed at opposing surfaces of the ion conductor (110). Preferably, the ion conductor (110) includes a chalcogenide material with Group IB or Group IIB metals. One of the two electrodes (120, 130) is preferably configured as a cathode and the other as an anode. When a voltage is applied to between the anode and cathode, a metal dendrite (140) grows from the cathode through the ion conductor (11) toward the anode. The grow rate of the dendrite may be stopped by removing the voltage or the dendrite may be retracted back toward the cathode by reversing the voltage polarity at the anode and the cathode. When a voltage is applied for a sufficient length of time, a continuous metal dendrite grows through the ion conductor (110) and connects the electrodes (120, 130), thereby shorting the device. The continuous metal dendrite then can be broken by applying another voltage.

Programmable sub-surface aggregating metallization structure and method of making same

Chemical stability enhancement of lithium conducting solid electrolyte plates using sputtered LiPON thin films

A neural prosthetic micro system (100) includes an electrode array (115) coupled to an integrated circuit (IC) (110) which IC may include signal conditioning and processing circuitry. The IC may include a high pass filter that passes signals representative of local field potential (LFP) activity in a subject's brain.

Neural prosthetic micro system

A microfabrication process has been developed to prepare thin film solid-state lithium batteries as small as 50 μm × 50 μm. Individual cells operate nominally at 3.9 V with 10 μA h cm−2 for a 0.25 μm thick cathode film. The cells are easily fabricated in series and parallel arrangement to yield batteries with higher voltage and/or capacity. Multiple charge/ discharge cycles are possible, though an apparent reaction of the in situ plated Li film with water or oxygen decreases cycle life several orders of magnitude from expected results. Further optimization of an encapsulating film will likely extend the cell cyclability. These microbattery arrays will be useful for providing on-chip power for low current, high voltage applications for microspacecraft and other miniaturized systems.

https://iopscience.iop.org/article/10.1088/0960-1317/12/1/309/pdf

William C. West

Papers

Programmable metallization cell structure and method of making same

Programmable sub-surface aggregating metallization structure and method of making same

Chemical stability enhancement of lithium conducting solid electrolyte plates using sputtered LiPON thin films

Neural prosthetic micro system

Fabrication and testing of all solid-state microscale lithium batteries for microspacecraft applications