Metallic Zn is a preferred anode material for rechargeable aqueous batteries towards a smart grid and renewable energy storage. Understanding how the metal nucleates and grows at the aqueous Zn anode ...is a critical and challenging step to achieve full reversibility of Zn battery chemistry, especially under fast‐charging conditions. Here, by combining in situ optical imaging and theoretical modeling, we uncover the critical parameters governing the electrodeposition stability of the metallic Zn electrode, that is, the competition among crystallographic thermodynamics, kinetics, and Zn2+‐ion diffusion. Moreover, steady‐state Zn metal plating/stripping with Coulombic efficiency above 99 % is achieved at 10–100 mA cm−2 in a reasonably high concentration (3 M) ZnSO4 electrolyte. Significantly, a long‐term cycling‐stable Zn metal electrode is realized with a depth of discharge of 66.7 % under 50 mA cm−2 in both Zn||Zn symmetrical cells and MnO2||Zn full cells.
Ultrafast metal electrodeposition in fast‐charging Zn batteries was investigated by in situ optical imaging and theoretical modeling. The critical parameters governing the electrodeposition stability of the metallic Zn electrode were uncovered, guided by which a highly reversible Zn metal electrode in an aqueous battery with a depth of discharge of 66.7 % at 50 mA cm−2 was achieved.
High-capacity Ni-rich layered oxides are promising cathode materials for secondary lithium-based battery systems. However, their structural instability detrimentally affects the battery performance ...during cell cycling. Here, we report an Al/Zr co-doped single-crystalline LiNi
Co
Mn
O
(SNCM) cathode material to circumvent the instability issue. We found that soluble Al ions are adequately incorporated in the SNCM lattice while the less soluble Zr ions are prone to aggregate in the outer SNCM surface layer. The synergistic effect of Al/Zr co-doping in SNCM lattice improve the Li-ion mobility, relief the internal strain, and suppress the Li/Ni cation mixing upon cycling at high cut-off voltage. These features improve the cathode rate capability and structural stabilization during prolonged cell cycling. In particular, the Zr-rich surface enables the formation of stable cathode-electrolyte interphase, which prevent SNCM from unwanted reactions with the non-aqueous fluorinated liquid electrolyte solution and avoid Ni dissolution. To prove the practical application of the Al/Zr co-doped SNCM, we assembled a 10.8 Ah pouch cell (using a 100 μm thick Li metal anode) capable of delivering initial specific energy of 504.5 Wh kg
at 0.1 C and 25 °C.
Lithium–oxygen (Li–O2) batteries possess a high theoretical energy density, which means they could become a potential alternative to lithium‐ion batteries. Nevertheless, the charging process of Li–O2 ...batteries requires much higher energy, due to the insulating nature of the discharge product. It has been revealed that the anion additive, lithium iodide (LiI), can tune the cell chemistry to form lithium hydroxide (LiOH) as the product and facilitate the kinetics during the charging process. Although numerous studies have been reported, the role of this additive is still under investigation. Herein, the recent advances focusing on the use of LiI in Li–O2 batteries are reviewed, its catalytic behavior on discharge and charge is discussed, and its synergistic effect with water is understood. The ambiguity existing among the studies are also revealed, and solutions to the current issues are introduced.
The role of iodide as an additive in lithium–oxygen batteries is not well understood, especially in the charging process. The recent advances on LiI are reviewed and the synergistic effect with water is discussed. Alternative approaches for enabling the charging process are also provided.
Integrating solid‐state electrolyte (SSE) into Li‐metal anodes has demonstrated great promise to unleash the high energy density of rechargeable Li‐metal batteries. However, fabricating a highly ...cyclable SSE/Li‐metal anode remains a major challenge because the densification of the SSE is usually incompatible with the reactive Li metal. Here, a liquid‐metal‐derived hybrid solid electrolyte (HSE) is proposed, and a facile transfer technology to construct an artificial HSE on the Li metal is reported. By tuning the wettability of the transfer substrates, electron‐ and ion‐conductive liquid metal is sandwiched between electron‐insulating and ion‐conductive LiF and oxides to form the HSE. The transfer technology renders the HSE continuous, dense, and uniform. The HSE, having high ion transport, electron shut‐off, and mechanical strength, makes the composite anode deliver excellent cyclability for over 4000 h at 0.5 mA cm−2 and 1 mAh cm−2 in a symmetrical cell. When pairing with LiFePO4 and sulfur cathodes, the HSE‐coated Li metal dramatically enhances the performance of full cells. Therefore, this work demonstrates that tuning the interfacial wetting properties provides an alternate approach to build a robust solid electrolyte, which enables highly efficient Li‐metal anodes.
A liquid‐metal‐derived hybrid solid electrolyte is fabricated by a wettability‐tuning transfer technique. By sandwiching liquid metal between electron‐insulating and ion‐conductive LiF and oxides, the resulting composite anodes can realize high cycling stability for >4000 h at 1 mAh cm−2.
Considering the natural abundance and low cost of sodium resources, sodium‐ion batteries (SIBs) have received much attention for large‐scale electrochemical energy storage. However, smart structure ...design strategies and good mechanistic understanding are required to enable advanced SIBs with high energy density. In recent years, the exploration of advanced cathode, anode, and electrolyte materials, as well as advanced diagnostics have been extensively carried out. This review mainly focuses on the challenging problems for the attractive battery materials (i.e., cathode, anode, and electrolytes) and summarizes the latest strategies to improve their electrochemical performance as well as presenting recent progress in operando diagnostics to disclose the physics behind the electrochemical performance and to provide guidance and approaches to design and synthesize advanced battery materials. Outlook and perspectives on the future research to build better SIBs are also provided.
Room temperature sodium‐ion batteries show great promise for large scale electrochemical energy storage application because of the low cost and large abundance of sodium resource. The progress and main challenges regarding the development of electrode, electrolytes, and advanced diagnostics are summarized with the aim of achieving a high energy density of over 400 Wh kg−1 on the cell level.
Tunnel‐structured MnO2 represents open‐framed electrode materials for reversible energy storage. Its wide application is limited by its poor cycling stability, whose structural origin is unclear. We ...tracked the structure evolution of β‐MnO2 upon Li+ ion insertion/extraction by combining advanced in situ diagnostic tools at both electrode level (synchrotron X‐ray scattering) and single‐particle level (transmission electron microscopy). The instability is found to originate from a partially reversible phase transition between β‐MnO2 and orthorhombic LiMnO2 upon lithiation, causing cycling capacity decay. Moreover, the MnO2/LiMnO2 interface exhibits multiple arrow‐headed disordered regions, which severely chop into the host and undermine its structural integrity. Our findings could account for the cycling instability of tunnel‐structured materials, based on which future strategies should focus on tuning the charge transport kinetics toward performance enhancement.
The lithiation front region of one β‐MnO2 nanowire analyzed by in situ TEM, where the MnO2/LiMnO2 interface features arrow‐headed disordered regions, is disclosed with its atomic structure clearly captured. The findings have a bearing on MnO2 open‐framed electrode materials for reversible energy storage.
Using a quaternary compound target, Cu(In,Ga)Se2 films are prepared using one‐step, selenization‐free direct current magneton sputtering (DcMS) and high power impulse magnetron sputtering (HiPIMS) ...methods. This study investigates how the sputtering power affects the composition, microstructure, morphology, and electrical characteristics of the films. Film crystallinity is found to be affected by the sputtering power utilized. The films deposited at 0.25 kW are amorphous, whereas those formed at 0.5–1 kW display a chalcopyrite structure with a (112)–preferred orientation. With increased sputtering power, the films’ crystal quality improves, displaying a homogeneous and compact morphology free of peeling and cracking. Elemental measurement of the CIGS films reveals that, depending on the deposition method, the film composition deviates from that of the target. The electrical properties of the deposited films vary with increasing sputtering power.
A single quaternary target is used to fabricate CIGS thin films utilizing two different magnetron sputtering processes that produce various levels of highly ionized plasmas. The growth, morphology, chemical composition, and electrical properties of the films, as well as how the sputtering process, which comprises the sputtering yield and sputtering transfer processes, affect them, are all thoroughly discussed.
LiCoO2 (LCO) is widely applied in today's rechargeable battery markets for consumer electronic devices. However, LCO operations at high voltage are hindered by accelerated structure degradation and ...electrode/electrolyte interface decomposition. To overcome these challenges, co‐modified LCO (defined as CB‐Mg‐LCO) that couples pillar structures with interface shielding are successfully synthesized for achieving high‐energy‐density and structurally stable cathode material. Benefitting from the “Mg‐pillar” effect, irreversible phase transitions are significantly suppressed and highly reversible Li+ shuttling is enabled. Interestingly, bonding effects between the interfacial lattice oxygen of CB‐Mg‐LCO and amorphous CoxBy coating layer are found to elevate the formation energy of oxygen vacancies, thereby considerably mitigating lattice oxygen loss and inhibiting irreversible phase transformation. Meanwhile, interface shielding effects are also beneficial for mitigating parasitic electrode/electrolyte reactions, subsequent Co dissolution, and ultimately enable a robust electrode/electrolyte interface. As a result, the as‐designed CB‐Mg‐LCO cathode achieves a high capacity and excellent cycle stability with 94.6% capacity retention at an extremely high cut‐off voltage of 4.6 V. These findings provide new insights for cathode material modification methods, which serves to guide future cathode material design.
Co‐modified LCO, which couples pillar structures with interface shielding, is successfully synthesized for achieving a high‐energy‐density and structurally stable cathode material. The as‐designed CB‐Mg‐LCO cathode achieves a high capacity and excellent cycle stability with 94.6% capacity retention at an extremely high cut‐off voltage of 4.6 V.
Lithium‐ion batteries (LIBs) based on LiNixCoyMn1‐x‐yO2 (NCM) cathode materials have been widely commercialized, because of their high energy density, favorable rate performance, and relatively low ...cost. However, with increased Ni content to further increase their energy density, their cycling stability deteriorates dramatically and thus fails to meet the commercial application requirements. The artificial cathode‐electrolyte‐interphase (CEI) is a promising approach to solve this problem. Here, a robust CEI is fabricated through in situ polymerization of ethylene carbonate induced by aluminum isopropoxide (AIP). By adding 1 wt.% AIP in a commercial electrolyte, the capacity retention of LiNi0.8Co0.1Mn0.1O2||Li cell at 1 C rate has been significantly increased from 80.8% to 97.8% with a highly reversible capacity of 176 mA h g−1 after 200 cycles. AIP can be also used as an additive during the slurry‐making process, enabling a reversible capacity of 170 mA h g−1 for LiCoO2 after 200 cycles even at a high charge cut‐off voltage of 4.6 V. It is confirmed that the in situ formed CEI layer can prevent the cathodes from cracking and reduce the irreversible phase transformation.
An organic/inorganic cathode‐electrolyte interphase (CEI) is fabricated by in situ polymerization with Aluminum isopropoxide. Such a CEI layer can effectively prevent the layered cathode from cracking, irreversible phase transformation, and electrolyte decomposition. As a result, both LiCoO2 and LiNi0.8Co0.1Mn0.1O2 cathodes exhibit a significantly improved cycling stability during harsh operation conditions such as high voltage and high‐temperature cycling.
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