Li-ion battery materials: present and future

Fuel cells powered by hydrogen from secure and renewable sources are the ideal solution for non-polluting vehicles, and extensive research and development on all aspects of this technology over the past fifteen years has delivered prototype cars with impressive performances. But taking the step towards successful commercialization requires oxygen reduction electrocatalysts--crucial components at the heart of fuel cells--that meet exacting performance targets. In addition, these catalyst systems will need to be highly durable, fault-tolerant and amenable to high-volume production with high yields and exceptional quality. Not all the catalyst approaches currently being pursued will meet those demands.

Electrocatalyst approaches and challenges for automotive fuel cells

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Rechargeable lithium-sulfur batteries.

Electrolytes and interphases in Li-ion batteries and beyond.

Electrocatalysis will play a key role in future energy conversion and storage technologies, such as water electrolysers, fuel cells and metal-air batteries. Molecular interactions between chemical reactants and the catalytic surface control the activity and efficiency, and hence need to be optimized; however, generalized experimental strategies to do so are scarce. Here we show how lattice strain can be used experimentally to tune the catalytic activity of dealloyed bimetallic nanoparticles for the oxygen-reduction reaction, a key barrier to the application of fuel cells and metal-air batteries. We demonstrate the core-shell structure of the catalyst and clarify the mechanistic origin of its activity. The platinum-rich shell exhibits compressive strain, which results in a shift of the electronic band structure of platinum and weakening chemisorption of oxygenated species. We combine synthesis, measurements and an understanding of strain from theory to generate a reactivity-strain relationship that provides guidelines for tuning electrocatalytic activity.

https://www.unicat.tu-berlin.de/fileadmin/user_upload/MAIN-bilder/UniCat/2_Research/24_Research_Highlights/NCHEM.623s.pdf

Lattice-strain control of the activity in dealloyed core–shell fuel cell catalysts

Lithium-ion-conducting solid electrolytes hold promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries. Achieving the combination of high ionic conductivity and a broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of the room-temperature lithium-ion conductivity by 3 orders of magnitude through the creation of nanostructured Li3PS4. This material has a wide electrochemical window (5 V) and superior chemical stability against lithium metal. The nanoporous structure of Li3PS4 reconciles two vital effects that enhance the ionic conductivity: (1) the reduction of the dimensions to a nanometer-sized framework stabilizes the high-conduction β phase that occurs at elevated temperatures, and (2) the high surface-to-bulk ratio of nanoporous β-Li3PS4 promotes surface conduction. Manipulating the ionic conductivity of solid electrolytes has far-reaching implication...

Anomalous high ionic conductivity of nanoporous β-Li3PS4

Lithium-sulfur (Li-S) batteries suffer from rapid capacity decay and low energy efficiency because of the low solubility of lithium sulfide (Li2S) in organic solvents and the intrinsic polysulfide shuttle phenomenon. Here, a novel additive, phosphorus pentasulfide (P2S5) in organic electrolyte, is reported to boost the cycling performance of Li-S batteries. The function of the additive is two-fold: 1) P2S5 promotes the dissolution of Li2S and alleviates the loss of capacity caused by the precipitation of Li2S and 2) P2S5 passivates the surface of lithium metal and therefore eliminates the polysulfide shuttle phenomenon. A Li-S test cell demonstrates a high reversible capacity of 900–1350 mAh g−1 and a high coulombic efficiency of ≥90% for at least 40 stable cycles at 0.1 C.

Phosphorous Pentasulfide as a Novel Additive for High‐Performance Lithium‐Sulfur Batteries

This work presents a facile synthesis approach for core–shell structured Li2S nanoparticles with Li2S as the core and Li3PS4 as the shell. This material functions as lithium superionic sulfide (LSS) cathode for long-lasting, energy-efficient lithium–sulfur (Li–S) batteries. The LSS has an ionic conductivity of 10–7 S cm–1 at 25 °C, which is 6 orders of magnitude higher than that of bulk Li2S (∼10–13 S cm–1). The high lithium-ion conductivity of LSS imparts an excellent cycling performance to all-solid Li–S batteries, which also promises safe cycling of high-energy batteries with metallic lithium anodes.

Lithium superionic sulfide cathode for all-solid lithium-sulfur batteries.

Lithium-ion-conducting solid electrolytes show promise for enabling high-energy secondary battery chemistries and solving safety issues associated with conventional lithium batteries. Achieving the combination of high ionic conductivity and outstanding chemical stability in solid electrolytes is a grand challenge for the synthesis of solid electrolytes. Herein we report the design of aliovalent substitution of Li4SnS4 to achieve high conduction and excellent air stability based on the hard and soft acids and bases theory. The solid electrolyte of composition Li3.833Sn0.833As0.166S4 has a high ionic conductivity of 1.39 mS cm−1 at 25 °C. Considering the high Li+ transference number, this phase conducts Li+ as well as carbonate-based liquid electrolytes. This research also addresses the compatibility of the sulfide-based solid electrolytes through chemical passivation.

Zengcai Liu

Papers

Lattice-strain control of the activity in dealloyed core–shell fuel cell catalysts

Anomalous high ionic conductivity of nanoporous β-Li3PS4

Phosphorous Pentasulfide as a Novel Additive for High‐Performance Lithium‐Sulfur Batteries

Lithium superionic sulfide cathode for all-solid lithium-sulfur batteries.

Air-stable, high-conduction solid electrolytes of arsenic-substituted Li4SnS4