Kosmotropic aqueous processing solution for green lithium battery cathode manufacturing

Improved electrochemical performance of Co-free Ni-rich cathode material for lithium-ion battery through multi-element composite modification

While the microelectronic industry is advancing at a rapid pace with smaller and smaller devices, the implementation of microelectro-mechanical systems (MEMS) on the market strongly depends on the availability of on-board power sources. However, traditional rechargeable batteries based on liquid electrolyte are not applicable due to the restrictions for on-chip design, size and inherent risk of leakage, which give rise to the development of all-solid-state thin film lithium-ion microbattery technology. As more energy is required in microelectronic devices, two-dimensional (2D) thin film microbatteries are no longer the ideal battery design because the limited footprint area results in a compromise between energy density and power density for the build-in power source. A move to all-solid-state three-dimensional (3D) architectures has been proposed as a promising approach to tackle this challenge and achieve both high energy and power densities within the footprint area [1]. 3D microbatteries generally require the fabrication of 3D nanoarchitectured electrodes with large capacity at high charge/discharge rates and long-term cycling capability. Without using binders or conductive additives, the direct fabrication of nanoarchitectures for the electrode materials on conductive substrates represents a new class of electrodes: 3D self-supported electrodes. Except as the key component for constructing 3D microbatteries, the 3D self-supported electrodes using flexible substrates (such as metal foil and carbon cloth) can be ideal electrodes for flexible lithium-ion batteries. Active research efforts have been devoted to the synthesis and characterization of various 3D self-supported electrodes on different conductive substrates. However, most of the previous works focused on the preparation of 3D self-supported nanoarchitectures for anode materials such as Si, Co3O4, and TiO2 [2], while very limited work has been reported on the 3D self-supported nanoarchitectures for cathode materials. The difficulty lies in the fact that the synthesis of cathode materials such as LiCoO2 and LiMn2O4 involves high temperature treatment, which is difficult for retaining the nanostructures after heat treatment. In this work, we present a new "hydrothermal lithiation" method to construct 3D LiCoO2 and LiMn2O4 nanoarrays on metal substrates [3,4]. Mesoporous low-temperature LiCoO2 nanowire arrays can be directly prepared by a two-step hydrothermal method and they can be easily converted into chain-like high-temperature LiCoO2 nanowire arrays through further calcination. The layered LiCoO2 nanowire arrays exhibit both high gravimetric capacity and areal capacity, while maintaining good cycling stability and rate capability. Similar method was used to prepare vertically aligned porous LiMn2O4 nanowall arrays, comprising highly crystallized spinel nanoparticles, on various conductive substrates without high temperature treatment. The "hydrothermal lithiation" can effectively convert Mn3O4 spinel nanowall arrays into LiMn2O4 spinel nanowall arrays without severe morphology change. The binder-free three-dimensional porous LiMn2O4 nanowall arrays exhibit high specific reversible capacity up to 131 mAh g-1 (or 0.29 mAh cm-2) as well as outstanding cycling stability and rate capability, making them promising as cathodes for both three-dimensional thin film lithium-ion microbatteries. The 3D cathode design and the effective low-temperature synthesis route will lead to new opportunities to develop high-performance microbatteries and flexible lithium-ion batteries.

Remarkable chemical adsorption and catalysis of monodisperse metallic cobalt sulfide nanoparticles enable long-cycling Li–S battery with high areal capacity and low shuttle constant

In this work, a Ni(OH)2@Ni foam binder‐free electrode was obtained through the corrosion of Ni foam with ultrapure water under hydrothermal conditions. The structure, morphology, and surface chemical states of the obtained Ni(OH)2@Ni foam were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The chemical formation mechanism is discussed. In addition, it was found that the loading amount and morphology of the deposited Ni(OH)2 depend largely on the corrosion time. Furthermore, electrodes corroded for different times were then directly used as working electrodes to investigate the areal and specific capacitances of the deposited Ni(OH)2 by using cyclic voltammetry, through which a relationship between the corrosion time, loading amount, morphology, and final capacitance is built up. The electrode with the highest areal capacitance was further studied with cyclic voltammetry, galvanostatic charge−discharge processes, as well as electrochemical impedance spectroscopy. The as‐prepared Ni(OH)2@Ni foam is a typical pseudocapacitance electrode. At a high current density of 5 mA cm−2, the electrode exhibits an areal capacitance of 0.863 F cm−2. For the deposited Ni(OH)2, its specific capacitance reaches 693 F g−1 at a current density of 4 A g−1. After 3000 charge−discharge cycles at a current density as high as 10 A g−1 (12.5 mA cm−2), the areal capacitance retains 77.3 % of its initial value. The findings in this work could be meaningful for the corrosion preparation of related electrodes and the design of binder‐free electrodes.

High-entropy strategy to suppress volumetric strain and enhance diffusion rate of Na3V2(PO4)2F3 cathode for durable and high-areal-capacity zinc-ion battery pouch cells

Enabling stable and high areal capacity solid state battery with Ni-rich cathode via failure mechanism study

Binder and conductive additive-free Si nanowires (NWs) grown directly on the current collector have shown great potential as next generation Li-ion battery anodes. However, low active material mass loadings and consequentially low areal capacities have remained a challenge in their development. Herein, we report the high-density growth of Si NWs on carbon cloth (CC) for use as Li-ion battery anodes. The NW growth reactions were carried out using a modified, glassware-based solvent vapor growth (SVG) process. Optimized growth conditions were applied to CC substrates to generate flexible Si NW anodes for Li-ion batteries. Battery testing revealed high areal charge and discharge capacities (>2 mAh/cm2) compared to Si NWs grown on stainless steel (SS) substrates (∼0.3 mAh/cm2) and stable long-term cycling with 80% capacity retention after 200 cycles. The findings reported herein represent a significant advancement in the field in terms of achievable areal capacity enabled by a low-cost glassware-based system.

Sodium-ion batteries (SIBs) are attracting attention as cost-effective alternatives to lithium-ion batteries (LIBs) for large-scale energy storage. Among SIB cathodes, P2-Na0.67Ni0.33Mn0.67O2 delivers high capacity and rate capability but suffers from rapid capacity fading under high-voltage charging due to a detrimental P2-O2 phase transition and interfacial side reactions. Here, we demonstrate a dual-modification strategy combining Cu2+ doping and MgO surface coating to address these challenges. The dual-modified cathode (Na0.67Ni0.28Cu0.05Mn0.67O2@MgO) delivers markedly improved performance: a high-capacity retention of 90.88% after 200 cycles at 1 C and significantly enhanced rate capability (95.23 mAh g-1 at 10 C). Ex situ XRD analyses reveal that the P2-O2 phase transition is effectively suppressed, leading to minimal structural change during cycling. DFT calculations reveal that the Cu-MgO dual modification synergistically enhances the electronic conductivity of the electrode and suppresses transition-metal layer gliding. The results indicate that Cu2+ doping enhances structural stability by regulating Na+/vacancy ordering and suppressing the high-voltage phase transition, whereas the MgO coating alleviates electrolyte-induced surface degradation and enhances Na+ diffusion kinetics. This work offers a valuable reference for designing high-performance cathode materials in sodium-ion battery systems.

Single‐crystal Li‐rich Mn‐based cathode materials (SLRMs) are promising for high‐energy lithium‐ion batteries due to their structural robustness. However, interfacial instability under high voltage triggers structural collapse and rapid capacity fading, hindering practical applications. Herein, an innovative strategy is proposed to deeply enhance the surface stability of SLRMs by constructing an Al 3+ ‐reinforced spinel shallow surface structure and an Al 3+ gradient‐doped layered subsurface structure in single‐crystal Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 . This composite structure effectively protects reactive oxygen species from electrolyte attack, mitigating capacity fading caused by interfacial side reactions. Theoretical calculations reveal that the oxygen vacancy formation energy of the Al 3+ ‐reinforced spinel shallow surface structure increases from 4.21 to 5.40 eV, while that of the Al 3+ ‐doped layered subsurface structure rises from 3.88 to 4.05 eV. Such enhancedoxygen vacancy formation energy effectively suppressed irreversible oxygen release and phase transitions, thereby strengthening the interfacial stability of SLRMs. The modified SLRMs deliver a discharge capacity of 232 mAh g −1 at 1 C, with only 5% capacity loss after 200 cycles. This study resolves interfacial degradation in SLRMs via atomic‐level tailored deep surface engineering, establishing a blueprint for designing cathode materials with structural robustness.

Interface compatibility between sulfide solid electrolytes and Ni-rich oxide cathode materials: factors, modification, perspectives

Multi-strategies interface and structure design of Li- and Mn-rich layered oxide for all-solid-state lithium batteries

Constructing an organic artificial cathode electrolyte interphase of multi-functions on single-crystal LiNi0.8Co0.1Mn0.1O2 cathode

Recently, water-soluble and aqueous polymers (water-based polymers) have attracted much attention as binders for lithium ion batteries (LIBs) because of the need for low-cost materials and environmentally compatible electrode fabrication processes. For example, N-methyl-2-pyrrolidone (NMP), which is listed as a carcinogenic chemical with reproductive toxicity is often used as a solvent to prepare a slurry (cathode material particle/conducting carbon additive/conventional polyvinylidene difluoride (PVdF) binder/ NMP solvent) employed in the fabrication process of electrode films on current collectors; this slurry should be recycled without releasing it to the atmospheric environment. Therefore, switching from a nonaqueous-based fabrication process to an aqueous-based process has been widely investigated. The hurdles in developing water-soluble and aqueous polymer binders for use in cathodes in LIBs are still high; improvements are necessary to increase the resistance to electrochemical oxidation and dissolution of metal oxide surfaces in water. In order to overcome these problems, a variety of polymer materials have been applied in the fabrication of cathodes with water-based slurries. In recent years, Li-rich solid-solution layered cathode materials comprising layered LiMO2 (M: transition metals) and Li2MnO3 have attracted much interest because some materials exhibit capacities as high as 250 mAh g-1 in the voltage range of 2.0 and 4.8 V. These materials are charged to above 4.5 V (vs. Li/Li+) to fully activate the Li2MnO3 component, and after activation, the cathodes are charged to 4.5 V to reach discharge capacities over 250 mAh g-1. To use these promising high-voltage and high-capacity cathodes in the next-generation Li-ion batteries prepared in environmentally compatible electrode fabrication processes with a water-based binder, water-based binders having high resistances to electrochemical oxidation during charging process should be developed. In this study, an aqueous hybrid polymer (TRD202A, JSR), which was composed of acrylic polymer and fluoropolymer, was selected as a binder for the Li-rich solid-solution layered cathode material Li[Ni0.18Li0.20Co0.03Mn0.58]O2. A cathode prepared with Li[Ni0.18Li0.20Co0.03Mn0.58]O2 particles, TRD202A binder, CMC and conductive carbon additive was tested and analyzed for charge/discharge capacity, cycle stability, rate performance, mechanical resistance, resistance of electrochemical oxidation, and changes of the surface composition and structure after water-treatment used for preparing water-based slurry. The water-based TRD202A cathode binder is a water-based emulsion and is designed with a unique hybrid polymer developed from acrylic polymer and fluoropolymer to satisfy both the requirements of high adhesion and chemical and electrochemical resistances. Wu and co-workers have already reported an application of the TRD202 binder in a Li-rich solid-solution cathode. They mentioned that the TRD202A binder can be used for high-voltage cathodes in the voltage range of 2.0-4.6 V [1], and its thermal stability is equivalent to that of PVdF. However, they have not examined the water-based binders for charge/discharge capacities, long cycle stability, rate performance, mechanical resistance, resistance of electrochemical oxidation, or changes of the surface composition and structure after water-treatment used for preparing the water-based slurry. We have examined in depth the above points with the Li-rich solid-solution cathode (3/5)Li2MnO3·(1/5)Li[Ni0.5Mn0.5]O2 ·(1/5)Li[Ni1/3Co1/3Mn1/3]O2. [1] Wu Q, Ha S, Prakash J, Dees DW, Lu W (2013) Electrochim. Acta 114:1-6

High-capacity O3-type layered sodium oxides are considered one of the most promising cathode materials for the next generation of Na-ion batteries (NIBs). However, these cathodes usually suffer from low high-rate capacity and poor cycling stability due to structure deformation, native air sensitivity, and interfacial side reactions. Herein, a multi-site substituted strategy is employed to enhance the stability of O3-type NaNi0.5 Mn0.5 O2 . Simulations indicate that the Ti substitution decreases the charge density of Ni ions and improves the antioxidative capability of the material. In addition, the synergistic effect of K+ and Ti4+ significantly reduces the formation energy of Na+ vacancy and delivers an ultra-low lattice strain during the repeated Na+ extraction/insertion. In situ characterizations verify that the complicated phase transformation is mitigated during the charge/discharge process, resulting in greatly improved structure stability. The co-substituted cathode delivers a high-rate capacity of 97mAhg-1 at 5C and excellent capacity retention of 81% after 400 cycles at 0.5C. The full cell paired with commercial hard carbon anode also exhibits high capacity and long cycling life. This dual-ion substitution strategy will provide a universal approach for the new rational design of high-capacity cathode materials for NIBs.

Lithium cobalt oxide (LCO) has been employed as cathode material for forty years. However, the low solubility of LCOs in water and strong electrostatic force and H-bonding between the LCOs particles limited the use of the aqueous binders in the LCO system. We report a feasible and universal approach to fabricating a complex cathode of LCO and reduced graphene oxide (RGO). Tannic acid (TA) could simultaneously disperse LCO and RGO particles. Meanwhile, the branched polyphenol TA acts as a “bridge” molecule for connecting the LCO and RGO, confirmed by the SEM test. The rheology properties of the PVDF slurry of cathode materials (LCO, LCO/, RGO, and TA/LCO/RGO) were also determined. It could be found that the TA could act as a crosslinking agent for the LCO and RGO particles, increasing the viscosity and storage modulus of the slurry. The cell employed the TA/LCO/RGO slurry as the cathode material, have a higher areal capacity, and had a higher redox potential than employed LCO/RGO and LCO as cathode materials, all of which could be attributed to the addition of the TA. This green molecule can be used to fabricate environmentally friendly and possibly biodegradable electrochemical energy storage devices.