Qiang Zhao

Bio: Qiang Zhao is an academic researcher from Tsinghua University. The author has contributed to research in topics: Materials science & Anode. The author has an hindex of 5, co-authored 8 publications receiving 299 citations. Previous affiliations of Qiang Zhao include Dalian Institute of Chemical Physics.

Cross-linked beta alumina nanowires with compact gel polymer electrolyte coating for ultra-stable sodium metal battery.

Abstract: Sodium metal batteries have potentially high energy densities, but severe sodium-dendrite growth and side reactions prevent their practical applications, especially at high temperatures. Herein, we design an inorganic ionic conductor/gel polymer electrolyte composite, where uniformly cross-linked beta alumina nanowires are compactly coated by a poly(vinylidene fluoride-co-hexafluoropropylene)-based gel polymer electrolyte through their strong molecular interactions. These beta alumina nanowires combined with the gel polymer layer create dense and homogeneous solid-liquid hybrid sodium-ion transportation channels through and along the nanowires, which promote uniform sodium deposition and formation of a stable and flat solid electrolyte interface on the sodium metal anode. Side reactions between the sodium metal and liquid electrolyte, as well as sodium dendrite formation, are successfully suppressed, especially at 60 °C. The sodium vanadium phosphate/sodium full cells with composite electrolyte exhibit 95.3% and 78.8% capacity retention after 1000 cycles at 1 C at 25 °C and 60 °C, respectively. Here the authors show a beta alumina nanowires/gel polymer composite electrolyte design. The dense and homogeneous solid-liquid hybrid sodium-ion transportation channels promote uniform sodium deposition and stripping and significantly improve the performance of a Na metal battery.

Spherical Li Deposited inside 3D Cu Skeleton as Anode with Ultrastable Performance.

Abstract: Porous current collectors are conducive to enhance the property of Li metal anode. Unfortunately, congestion in diffusion path during plating process damages the effects of current collectors. Herein, we developed a 3D Cu skeleton with open micrometer-sized pores by NaCl-assisted powder-sintering method. The unobstructed pores of 3D Cu skeleton help to reduce congestion during plating, thus most of Li deposited inside the current collector. Besides, the large smooth surface promotes the deposition of Li with smooth spherical shape, which mitigating Li dendrite growth. As a result, better safety and rechargeability of Li metal anode were achieved in this design.

Expanded-graphite embedded in lithium metal as dendrite-free anode of lithium metal batteries

Abstract: Lithium (Li) metal batteries present huge challenges in their practical application, including dendrite growth and infinite volume changes of the Li metal anode during cycling. Lightweight and porous carbon materials can effectively accommodate Li metal and suppress Li dendrite growth. Herein, we report a composite anode prepared by pressing the mixture of expanded-graphite (EG) with Li powder, followed by heating at 200 °C (Li–EG). The porous and well-conducting EG was uniformly embedded in Li metal, which provided sufficient surface and space for accommodating and attracting the Li metal. The in situ lithiation reaction between EG and Li metal formed LiC6 that exhibited excellent lithiophilicity and ionic conductivity, which provided abundant nucleation sites and reduced the Li nucleation barrier as well as the overpotential, thereby effectively inhibiting the nucleation and growth of Li dendrites. In addition, the EG embedded in Li metal composite anode presented preferable thermal stability. Consequently, the EG/Li half-cell exhibited a life span of 1000 h at a current density of 1 mA cm−2 and could be stably cycled for 1500 cycles at an ultra-high current of 10 mA cm−2. As a result, the LiFePO4‖Li–EG full-cell presented capacity retention as high as 93.5% after 500 cycles. The facile preparation method and excellent electrochemical performance render the composite anode a promising option in the practical use of Li metal batteries.

Progress on Lithium Dendrite Suppression Strategies from the Interior to Exterior by Hierarchical Structure Designs.

Abstract: Lithium (Li) metal is promising for high energy density batteries due to its low electrochemical potential (-3.04 V) and high specific capacity (3860 mAh g-1 ). However, the safety issues impede the commercialization of Li anode batteries. In this work, research of hierarchical structure designs for Li anodes to suppress Li dendrite growth and alleviate volume expansion from the interior (by the 3D current collector and host matrix) to the exterior (by the artificial solid electrolyte interphase (SEI), protective layer, separator, and solid state electrolyte) is concluded. The basic principles for achieving Li dendrite and volume expansion free Li anode are summarized. Following these principles, 3D porous current collector and host matrix are designed to suppress the Li dendrite growth from the interior. Second, artificial SEI, the protective layer, and separator as well as solid-state electrolyte are constructed to regulate the distribution of current and control the Li nucleation and deposition homogeneously for suppressing the Li dendrite growth from exterior of Li anode. Ultimately, this work puts forward that it is significant to combine the Li dendrite suppression strategies from the interior to exterior by 3D hierarchical structure designs and Li metal modification to achieve excellent cycling and safety performance of Li metal batteries.

Approaching Practically Accessible Solid-State Batteries: Stability Issues Related to Solid Electrolytes and Interfaces

Abstract: Solid-state batteries have been attracting wide attention for next generation energy storage devices due to the probability to realize higher energy density and superior safety performance compared with the state-of-the-art lithium ion batteries. However, there are still intimidating challenges for developing low cost and industrially scalable solid-state batteries with high energy density and stable cycling life for large-scale energy storage and electric vehicle applications. This review presents an overview on the scientific challenges, fundamental mechanisms, and design strategies for solid-state batteries, specifically focusing on the stability issues of solid-state electrolytes and the associated interfaces with both cathode and anode electrodes. First, we give a brief overview on the history of solid-state battery technologies, followed by introduction and discussion on different types of solid-state electrolytes. Then, the associated stability issues, from phenomena to fundamental understandings, are intensively discussed, including chemical, electrochemical, mechanical, and thermal stability issues; effective optimization strategies are also summarized. State-of-the-art characterization techniques and in situ and operando measurement methods deployed and developed to study the aforementioned issues are summarized as well. Following the obtained insights, perspectives are given in the end on how to design practically accessible solid-state batteries in the future.

Interfaces and Interphases in All-Solid-State Batteries with Inorganic Solid Electrolytes.

Abstract: All-solid-state batteries (ASSBs) have attracted enormous attention as one of the critical future technologies for safe and high energy batteries. With the emergence of several highly conductive solid electrolytes in recent years, the bottleneck is no longer Li-ion diffusion within the electrolyte. Instead, many ASSBs are limited by their low Coulombic efficiency, poor power performance, and short cycling life due to the high resistance at the interfaces within ASSBs. Because of the diverse chemical/physical/mechanical properties of various solid components in ASSBs as well as the nature of solid-solid contact, many types of interfaces are present in ASSBs. These include loose physical contact, grain boundaries, and chemical and electrochemical reactions to name a few. All of these contribute to increasing resistance at the interface. Here, we present the distinctive features of the typical interfaces and interphases in ASSBs and summarize the recent work on identifying, probing, understanding, and engineering them. We highlight the complicated, but important, characteristics of interphases, namely the composition, distribution, and electronic and ionic properties of the cathode-electrolyte and electrolyte-anode interfaces; understanding these properties is the key to designing a stable interface. In addition, conformal coatings to prevent side reactions and their selection criteria are reviewed. We emphasize the significant role of the mechanical behavior of the interfaces as well as the mechanical properties of all ASSB components, especially when the soft Li metal anode is used under constant stack pressure. Finally, we provide full-scale (energy, spatial, and temporal) characterization methods to explore, diagnose, and understand the dynamic and buried interfaces and interphases. Thorough and in-depth understanding on the complex interfaces and interphases is essential to make a practical high-energy ASSB.

New Concepts in Electrolytes.

Abstract: Over the past decades, Li-ion battery (LIB) has turned into one of the most important advances in the history of technology due to its extensive and in-depth impact on our life. Its omnipresence in all electric vehicles, consumer electronics and electric grids relies on the precisely tuned electrochemical dynamics and interactions among the electrolytes and the diversified anode and cathode chemistries therein. With consumers' demand for battery performance ever increasing, more and more stringent requirements are being imposed upon the established equilibria among these LIB components, and it became clear that the state-of-the-art electrolyte systems could no longer sustain the desired technological trajectory. Driven by such gap, researchers started to explore more unconventional electrolyte systems. From superconcentrated solvent-in-salt electrolytes to solid-state electrolytes, the current research realm of novel electrolyte systems has grown to unprecedented levels. In this review, we will avoid discussions on current state-of-the-art electrolytes but instead focus exclusively on unconventional electrolyte systems that represent new concepts.

Progress and Perspective of Ceramic/Polymer Composite Solid Electrolytes for Lithium Batteries

Abstract: Solid composite electrolytes (SCEs) that combine the advantages of solid polymer electrolytes (SPEs) and inorganic ceramic electrolytes (ICEs) present acceptable ionic conductivity, high mechanical strength, and favorable interfacial contact with electrodes, which greatly improve the electrochemical performance of all-solid-state batteries compared to single SPEs and ICEs. However, there are many challenges to overcome before the practical application of SCEs, including the low ionic conductivity less than 10-3 S cm-1 at ambient temperature, poor interfacial stability, and high interfacial resistance, which greatly restrict the room temperature performance. Herein, the advances of SCEs applied in all-solid-state lithium batteries are presented, including the Li ion migration mechanism of SCEs, the strategies to enhance the ionic conductivity of SCEs by various morphologies of ICEs, and construction methods of the low resistance and stable interfaces of SCEs with both cathode and anode. Finally, some typical applications of SCEs in lithium batteries are summarized and future development directions are prospected. This work presents how it is quite significant to further enhance the ionic conductivity of SCEs by developing the novel SPEs with the special morphology of ICEs for advanced all-solid-state lithium batteries.

Challenges in lithium metal anodes for solid state batteries

Abstract: In this Perspective, we highlight recent progress and challenges related to the integration of lithium metal anodes in solid-state batteries. While prior reports have suggested that solid electroly...