Stable Energy Storage Research Articles

Synergistic effect and enhanced safety of double dynamic solid polymer electrolytes for lithium metal batteries

A solid polymer electrolyte with low mechanical strength and poor flexibility will cause mechanical degradation, short circuits, or functional failures in lithium ion batteries (LIBs). Therefore, introducing an double dynamic solid polymer electrolytes with high ionic conductivity, good mechanical strength, and excellent self-healing ability for stabilizing the solid electrolyte interface, preventing battery fire, and suppressing Li dendrite growth will further improve the reliability, security, and lifetime of the LIBs. Herein, a series of dual dynamic self-healing solid polymer electrolytes (DD-shSPEs) are developed via the Schiff base reaction between different molar ratios of polyethylene glycol derivative (tat-PEG) and terephthalaldehyde. The hydrogen bond and the highly reversible imine bonds endow DD-shSPEs with rapid self-repairing capacity to cure mechanical damage within 5 min at normal temperature. The self-healing polymer electrolytes also exhibit excellent stretchability, which can satisfy the external deformation of the battery. Meanwhile, after self-healing, the ionic conductivities of the electrolytes can hold the original values. Also, the initial discharge capacity (IDC) of the battery based on DD-shSPEs reach to 149.3 mAh g-1 under a current rate of 0.1 C, and still maintains 144.2 mAh g−1 after 100 cycles. Besides, the polymer electrolyte (PE) also exhibits good interfacial stability and have a cycle life of more than 650 h at a current density of 0.2 mA cm-2. Accordingly, this work shows that the high-performance PE based on self-healing materials is promising for constructing high stable solid-state energy storage device.

Experimental and numerical investigations on radiant floor heating system integrated with macro-encapsulated phase change material

Macro-encapsulated phase change material (PCM) with PCM as core and polymer as shell is reported an extremely stable energy storage medium in radiant floor heating system (RFHS). Herein, RFHS-based rooms with and without macro-encapsulated PCM are built, and the comfort and economy of the corresponding rooms are evaluated. Experimental results show that the room with macro-encapsulated PCM has longer thermal comfort time and slighter temperature deviation than without, according to the comfort standard. Then, a 3D unsteady heat transfer model is established and corrected by experimental data. Results show that macro-encapsulated PCM as temperature buffer layer regulates the heating-cooling rate of room and forms a semi-elliptic air radiant temperature zone. The room with macro-encapsulated PCM has lower daily electricity cost (c‾) of 0.2595 CNY/day and higher comfort time ratio of inside air (t‾) of 80.88%, decreased by 36.71% and increased by 15.43% than without, respectively. The thermal conductivities of shell and core of macro-encapsulated PCM are orthogonally optimized to be respectively 0.25 and 1.00 W/(m·K), with lowest c‾ (0.2480 CNY/day) and higher t‾ (85.47%), decreased by 4.43% and increased by 5.67% than pre-optimization. When the ambient temperature changes within −10∼10 °C, the input power of the room with macro-encapsulated PCM is orthogonally optimized to save c‾ by 35.91%∼39.39% than without.

Bottom growth strategy for high areal capacity rechargeable aluminum batteries

Among all practical methods to build the high specific energy battery, increasing the areal loading of active materials is a promising choice. However, increasing the areal loading of the active material will inevitably increase the areal deposition amount of aluminum. If aluminum undergoes uneven deposition, dendrite growth is an inevitable problem with the increase of aluminum deposits. In this paper, an anode structure with bottom growth mode (2P-Al2O3/Al) are proposed through anodic oxidation and laser etching technology, which can provide an inverted electric field strength (Ebottom>Etop) to induce the directional deposition of Al. We have grown a dense alumina layer on the surface and pores of the 2P-Al2O3/Al electrode, which can form a stable electrode/electrolyte interface as an SEI layer. The in-situ deposition image of the electrode indicates that aluminum preferentially grows at the bottom of the electrode, and the deposition process of aluminum is very uniform. In addition, the electrode exhibits excellent cycling stability in both half and full batteries. Even under the large areal special capacity of 20 mAh·cm−2 without presenting significant interfacial degradation and early short circuit, it can operate cycle over 900 h, which is more than 3 times that of planer aluminum anode. This technology opens a new platform for designing highly safe and stable long-term energy storage system.

Energy saving phase change energy storage thermochromic liquid crystal display

Phase change energy storage microcapsules (PCESM) improve energy utilization by controlling the temperature of the surrounding environment of the phase change material to store and release heat. In this paper, a phase change energy storage thermochromic liquid crystal display (PCES-TC-LCD) is designed and prepared for the first time. The as-prepared PCES-TC-LCD has a stable bilayer structure, where the lower layer is a thermochromic LC layer produced by centrifugal spin coating and high temperature curing, and the upper layer is a polymer-stabilized liquid crystal (PSLC) film with phase change energy storage properties obtained by polymerization-induced phase separation method. The prepared PCES-TC-LCD can realize the functions of triple-field driven and phase change energy storage, which has strong research value. In the performance experiments, the electro-optical properties of PCES-TC-LCD were analyzed and optimized by three sets of experiments on liquid crystal content, polymerization time, and PCESM content. In the film formation study, PCES-TC-LCD based on rigid/flexible substrates were prepared, respectively. The phase change energy storage function of PCES-TC-LCD was performed by differential scanning calorimetry (DSC) and infrared thermography. The devices formed on rigid or flexible substrates with stable phase change energy storage performance, which has great application value by reducing the external energy input, prolonging the thermochromic time and achieving energy saving effects.

Inside Cover Picture

According to the existing forms of rare earth elements, we classify rare earth promoted transition metal sulfides into rare earth doped transition metal sulfides, rare earth interface promoted transition metal sulfides, and rare earth structure promoted transition metal sulfides. We also prospect their applications in OER, HER, ORR, and CO2RR, as well as in other electrocatalytic fields. In today's increasingly serious energy problem, it is of great significance to rationally utilize rare earths to promote the regulation of transition metals, enabling them to achieve more efficient and stable energy storage and conversion. More details are given in the article by Xi et al. on page 1740—1752.image

Stabilizing polar P21ma phase in Bi0.5Na0.5TiO3-Na0.91Bi0.09Nb0.94Mg0.06O3 relaxors by CaTiO3 additive to promote energy storage density, efficiency and discharge rate

Eco-friendly Bi0.5Na0.5TiO3 relaxor ferroelectric has attracted considerable attention for pulsed power capacitor applications due to its large saturation polarization. However, high remnant polarization and low breakdown strength (Eb) restrict its application. Herein, linear dielectric CaTiO3 (CT) is introduced into Bi0.5Na0.5TiO3-Na0.91Bi0.09Nb0.94Mg0.06O3 (BNT-NBNM) ceramic to enhance its Eb. Interestingly, CT additive can stabilize polar orthorhombic P21ma phase. As a result, a high recoverable energy density of 6.4 J/cm3 and a high efficiency of 92% at 400 kV/cm as well as an ultrafast discharge rate of 57 ns are obtained in 0.63BNT-0.27NBNM-0.1CT ceramic. Furthermore, temperature dependent Raman spectra reveal that the superior temperature stability of energy storage properties over the temperature span of 30–150 °C is due to insensitive B-O vibration to temperature. The results demonstrate an effective strategy to construct superior and stable BNT-based energy storage materials for pulsed power capacitor applications.

Optimized on melamine sponges for highly stable and efficient hydrated salt-based solar thermal energy storage

Optimized on melamine sponges for highly stable and efficient hydrated salt-based solar thermal energy storage

Tailoring potential window of aqueous electrolyte via steric molecular engineering for high voltage supercapacitors

Manufacturing economical and environmentally friendly aqueous electrolytes having a large operating potential is crucial to accomplish safe, high-energy and long-life supercapacitors. An emerging approach of superconcentrated Water-in-Salt (WIS) electrolyte significantly improves the performance through a stable, improved thermodynamic potential of water by reducing the free water molecules in the electrolyte. However, this approach raises concern about the cost and toxicity. By the way, we have achieved a similar performance by creating a hydrogen bonding network through the incorporation of additive with electrolyte, which suppresses the water electrolysis even at low salt concentration. This work demonstrates a hydrogen bond constructed electrolyte (Steric effect) using the additive to reduce water activity. In that way, it delivered an extensive operational voltage (>2.3 V) to the electrolyte at a low salt concentration (5M NaClO4). Further, the carbon-based symmetric supercapacitor cell with this electrolyte delivered a capacitance of 112 mF with good capacitance retention (71.4%) after 50,000 cycles. Further, the cell showed its excellency via a low self-discharge rate and leakage current. The performance of the coin cell-type supercapacitor is evaluated as per IEC standards and as well as the traditional method and compared with superconcentrated Water-in-Salt NaClO4. This work opens up new direction for designing high-voltage water-based electrolyte for inexpensive and very stable energy storage devices.

Oriented High Thermal Conductivity Solid-Solid Phase Change Materials for Mid-Temperature Solar-Thermal Energy Storage.

As the global energy crisis intensifies, the development of solar energy has become a vital area of focus for many nations. The utilization of phase change materials (PCMs) for photothermal energy storage in the medium temperature range holds great potential for various applications, but their conventional forms face several challenges. For instance, the longitudinal thermal conductivity of photothermal PCMs is inadequate for effective heat storage on the photothermal conversion surface, and there is a risk of leakage due to repeated solid-liquid phase transitions. Here, we report a solid-solid phase change material, tris(hydroxymethyl)aminomethane (TRIS), which has a phase change temperature of 132 °C in the medium temperature range, enabling high-grade and stable solar energy storage. To overcome the low thermal conductivity problem, we propose a large-scale production of oriented high thermal conductivity composites by compressing a mixture of TRIS and expanded graphite (EG) using the pressure induction method to create in-plane highly thermally conductive channels. Remarkably, the resulting phase change composites (PCCs) exhibit a directional thermal conductivity of 21.3 W/(m·K). Furthermore, the high phase change temperature (132 °C) and large phase change entropy (213.47 J/g) enable a large-capacity high-grade thermal energy to be used. The developed PCCs, when combined with selected photo-absorbers, exhibit efficient integration of solar-thermal conversion and storage. Additionally, we also demonstrated a solar-thermoelectric generator device with an energy output of 93.1 W/m2, which is close to the power of photovoltaic systems. Overall, this work provides a technological route to the large-scale fabrication of mid-temperature solar energy storage materials with high thermal conductivity, high phase change enthalpy, and no risk of leakage, and also offers a potential alternative to photovoltaic technology.

Form-stable cold storage phase change materials with durable cold insulation for cold chain logistics of food

Every year, many foods are discarded in the process of transportation because they could not be kept fresh for a long time, resulting in great food and economic loss. Phase change technology for cold energy storage has the advantages of stable temperature and high energy storage density, and it has great application potential in cold chain logistics. However, how to endow it with shape stability before and after phase change and machinability while maintaining high cold-insulation performance is of great importance for expanding its application in the fields of cold chain logistics with higher requirements. Herein, a novel form-stable cold energy storage phase change material (FCPCM) with ice as phase change component and a polyether-based three-dimensional network as skeleton was reported. FCPCMs exhibit excellent shape stability, i.e., no water leakage, owing to the coaction of capillary forces and hydrogen bonding between two phase interfaces. FCPCM demonstrated excellent thermal properties (ΔHm = 285.9 J/g and Tp of melting = 1.9 °C) and durable cold-insulation performance, and it could maintain cold temperature 1.85 times longer than ice. FCPCM could prolong the preservation time of litchi, indicating its excellent potential in cold chain logistics of fruit, vegetables, and other foods to enhance food quality and safety.

High-efficiency energy storage in Nd-doped (1-x)BiFeO3–xBaTiO3 relaxor ferroelectric ceramics

Dielectric capacitors as energy storage electronics have drawn much attention due to ultrahigh power densities with quick charging and discharging rates. In this report, A-site Nd-doped (1-x)BiFeO3-xBaTiO3 (x = 0.2–0.45) relaxor ferroelectric ceramics with superior storage efficiencies were prepared with 0.1 wt% MnO2 additive. Energy-storage efficiency (η) increases from 63.7% to 89% at 190 kV/cm as BaTiO3 increases accompanied by recoverable energy densities (Wrec) in the range of 2.5–2.7 J/cm3. The energy-storage performance persists thermally stable up to 125 °C. The superior storage efficiency is associated with growth of the cubic Pm-3m symmetry and the core-shell structure with increasing BaTiO3 content. The formation of nanocluster/nanomosaic structure also plays an essential role as a barrier in suppressing the long-range polarization order. This work provides a design of binary rare-earth doped BiFeO3–BaTiO3 dielectric ceramics for thermally stable and high-efficiency electrical energy storage.

Sewable high-performance poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/layered double hydroxide core-shell fiber electrodes for flexible supercapacitors

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based fibers are one of the most competitive fiber-type electrodes but still suffer from low electrochemical surface areas (ECSAs) and oversensitivity to humidity for fiber supercapacitor applications. Herein, through rational design, a sewable core-shell fiber electrode of PEDOT:PSS/waterborne polyurethane (WPU) fiber wrapped with nickel/cobalt-layered double hydroxides (NiCo-LDH) has been synthesized via wet-spinning and solution reaction. The fiber core acts as a conductive channel for charge carrier transport. The NiCo-LDH shell possesses unique hybrid architectures of honeycomb-like nanosheet array and hollow nanocages, which provide numerous electrochemical active sites. Simultaneously, the water barrier effect of the NiCo-LDH shell and the interaction between Co2+/Ni2+ and PSS reduce fiber water uptake, thus endowing the fiber with a better geometric stability with low swelling ratio. The as-prepared PEDOT:PSS/LDH fiber has a large ECSA (4060 cm2 g−1) and ultrahigh conductivities no matter in dry (1237.3 S cm−1) or wet (1018.7 S cm−1) state. It also exhibits a high capacitance (188.5 F g−1 at 1 A g−1) and long lifespan (capacitance retention of 94% after 10,000 cycles). The fiber-based supercapacitor shows superb flexibility with stable capacitive behavior under deformation. These characteristics manifest the potential of PEDOT:PSS/LDH fibers for stable high-performance energy storage to support wearable electronics.

Efficient direct solar-driven thermochemical energy storage of (AlMgFeMn)OxCaCO3 pellets in a fluidized bed reactor

Calcium looping (CaL) is one of the most promising thermochemical energy storage technologies for high-temperature applications such as next-generation concentrated solar power (CSP) systems. However, most previous investigations have mainly focused on optimizing Calcium-based materials to maintain their reactivity during cycling, while their behavior in reactors under direct solar irradiation has rarely been reported. In this paper, highly efficient and stable direct solar-driven thermochemical energy storage in fluidized reactors is demonstrated. (AlMgFeMn)OxCaCO3 pellets demonstrated excellent long-term stability with an energy storage density of more than 85% of the initial value after 100 cycles. The underlying mechanism can be attributed to the presence of poly-oxide (AlMgFeMn)Ox crystals, which prevent crystallite growth and sintering, as confirmed by in-situ X-ray diffraction analysis. Moreover, the solar-thermal conversion efficiency of (AlMgFeMn)OxCaCO3 pellets in fluidized bed reactors is significantly improved from 9% to 19% thanks to the considerably increased average solar absorptance and fast reaction kinetics over white (AlMg)OxCaCO3 pellets. The experimental analysis using an operando fluidized thermogravimetric analyzer (F-TGA) further revealed that the interparticle diffusion control limitation in traditional TGA or fixed bed and localized overheating due to Gaussian distribution of solar irradiation are successfully relieved in a fluidized bed. We further suggest that steam has a positive effect on enhancing reaction kinetics and stability by performing 10 energy storage/release cycles of (AlMgFeMn)OxCaCO3 pellets under direct irradiation of concentrated light due to the increase of surface area after rehydration and the higher OH reactivity toward CaO. This work paves the way for the application of solar-driven fluidized bed reactors for scalable thermochemical energy storage.

Phase separation strategy achieves printable corrosion-resistant ternary SiOC supercapacitors with sustained capacitance increase

Carbon-ceramic material with well-designed components and architectures is an effective strategy to fulfill the chemical-stability requirements of long-life supercapacitors. Herein, we proposed a direct cation-induced component recombination strategy to convert the intrinsically insulated SiOC ceramic to an electrochemically active ternary state for stable and long-life capacitive energy storage. Meanwhile, the cation-induced component recombination process can be directly coupled to advanced photocurable 3D printing technology to create the integral ternary SiOC electrode with various 3D structures for a complex-shaped supercapacitor. As a result, the ternary SiOC electrodes with four-type triply periodic minimal surface structures have been successfully printed and used in an alkaline supercapacitor with high corrosivity. The integral ternary SiOC electrode with Diamond structure demonstrates high capacity (756 mF·g−1 at 1.7 mA·g−1). The symmetrical supercapacitor based on ternary SiOC electrodes with a Diamond structure exhibits outstanding long-term durability (181.5 % capacity retention after 10,000 cycles) in highly corrosive environments. In addition, the ternary SiOC electrode also shows extremely high cycling stability in highly corrosive seawater, with a capacity retention rate of over 95 % after 20,000 cycles. Therefore, this novel 3D-printed ternary SiOC electrodes provides an efficient approach for developing long-term stable and reliable supercapacitors for applications in highly corrosive environments.

Upcycling of nickel oxide from spent Ni-MH batteries as ultra-high capacity and stable Li-based energy storage devices

Due to the rapid expansion of portable electronics and electric vehicles market, the projected demand of rechargeable batteries is huge and may lead to shortage of critical minerals, especially nickel (Ni) metal. In the present study, we upcycled NiO material from spent Nickel–Metal hydride batteries (Ni-MH) as electrodes in Li-ion battery (LIB) and supercapacitor. Intriguingly, recycled NiO was applied successfully to develop sustainable LiNi0.5Mn1.5O4 (LNMO) cathode, delivering the promising capacity. As the recovered NiO-anode in LIBs, the device exhibited ultrahigh capacity of 1248 mAh g−1 at 0.1C, exhibiting excellent rate capability and cycle life in traditional carbonate-based electrolyte. The full cell with NMC cathode gave a high discharged capacity of 137.4 mAh/g. Addition to conventional electrolyte, a safe and non-flammable diglyme electrolyte using recovered NiO was investigated under identical condition. The maximum reversible capacity of 642 mAh g−1 at 0.1C was achieved along with good rate performance. Likewise, the NiO-based supercapacitor electrode delivered a maximum capacitance of 106C g−1 at 0.5 A g−1. Hence, upcycling of abundant NiO waste as low-cost electrode materials from end-of-life batteries paves the way for future generation of Li-based energy storage devices and sustainable supply of critical minerals and clean environment.

Constructed TiO 2/WO 3 heterojunction with strengthened nano-trees structure for highly stable electrochromic energy storage device

Tungsten trioxide (WO₃) has been widely regarded as a prospective bifunctional material due to its electrochromic and pseudocapacitive properties, while still facing the dilemma of inadequate cycle stability and trapping-induced degradation. Here, inspired by the trees-strengthening approach, a unique titanium dioxide (TiO₂) nanorod arrays strengthened WO₃ nano-trees (TWNTs) heterojunction was rationally designed and constructed. In sharp contrast to the transmittance modulation (Δ<i>T</i>) attenuation of primary WO₃ nano-trees during cycling, the TWNTs film showed not only excellent electrochromic performance but also fascinating cycle stability (77.35% retention of the initial Δ<i>T</i> after 10,000 cycles). Besides, the trapping-induced degradation could be easily rejuvenated by a potentiostatic de-trapping process. An electrochromic energy storage device (EESD) was further assembled based on the TWNTs film to deliver excellent Δ<i>T</i> (up to 79.5% at 633 nm), fast switching speed (<i>t</i>_c/<i>t</i>_b =1.9 s/14.8 s), extremely high coloration efficiency value (443.4 cm²·C⁻¹), and long-term cycle stability (over 10,000 charge/discharge cycles). This innovative study provided in-depth insights into the electrochromism nature and a significant step in the realization of stable electrochromic-energy storage application, paving the way for multifunctional smart windows as well as next-generation optoelectronic devices.

OPTIMIZATION OF ANNUAL OPERATION PLAN OF PV, BT AND FC COOPERATION SYSTEM FOR HOUSES

Photovoltaic power generation has attracted attention as a renewable energy technology for households as societies make efforts toward decarbonization. However, it is difficult for PV to supply stable electric power and energy storage since the power generation varies depending on the weather. Therefore, in this study, annual operation plan of a PV, BT and FC (PEFC) cooperation system is optimized by mixed integer liner programming. As a result, optimization of this cooperation system reduced primary energy consumption and operation costs, and increased electricity self-sufficiency.

Rapid and stable calcium-looping solar thermochemical energy storage via co-doping binary sulfate and Al–Mn–Fe oxides

Solar thermochemical energy storage based on calcium looping (CaL) process is a promising technology for next-generation concentrated solar power (CSP) systems. However, conventional calcium carbonate (CaCO3) pellets suffer from slow reaction kinetics, poor stability, and low solar absorptance. Here, we successfully realized high power density and highly stable solar thermochemical energy storage/release by synergistically accelerating energy storage/release via binary sulfate and promoting cycle stability, mechanical strength, and solar absorptance via Al–Mn–Fe oxides. The energy storage density of proposed CaCO3 pellets is still as high as 1455 kJ kg−1 with only a slight decay rate of 4.91% over 100 cycles, which is higher than that of state-of-the-art pellets in the literature, in stark contrast to 69.9% of pure CaCO3 pellets over 35 cycles. Compared with pure CaCO3, the energy storage power density or decomposition rate is improved by 120% due to lower activation energy and promotion of Ca2+ diffusion by binary sulfate. The energy release or carbonation rate rises by 10% because of high O2− transport ability of molten binary sulfate. Benefiting from fast energy storage/release rate and high solar absorptance, thermochemical energy storage efficiency is enhanced by more than 50% under direct solar irradiation. This work paves the way for application of direct solar thermochemical energy storage techniques via achieving fast energy storage/release rate, high energy density, good cyclic stability, and high solar absorptance simultaneously.

One-Step Electrochemical Synthesis of AlO x -Passivated Twisted-Phosphorene Nanosheets for Potentially Stable Energy Storage Devices.

Black phosphorus (BP), a promising 2D material for electronics, energy storage, catalysis, and sensing, has sparked a research boom. However, exfoliated thin-layered BP is unstable and can easily be degraded under environmental conditions, severely limiting its practical applications. In this context, a simple and cost-effective method has been proposed that involves electrochemically exfoliating BP and simultaneously electrochemically depositing aluminum oxide (AlO x ) for passivation of the exfoliated BP. The ambient stability of the exfoliated BP is studied using a time-dependent atomic force microscope (AFM). The AlO x capping layer significantly improves the environmental stability of BP compared to uncapped BP. The thermal stability of the resulting BP is evaluated using power-dependent Raman spectroscopy. The results show that the AlO x -passivated BP has increased thermal stability, with only a slight shift in peak position toward higher Raman power intensity. These properties can make the material suitable for stable energy storage devices. Interestingly, the electrochemical exfoliation and passivation processes resulted in the BP with a twist angle (9.86°), which is expected to exhibit unique electronic properties similar to those of graphene with a twist angle.

Flexible lead-free Na0.5Bi0.5TiO3-based film capacitor with stable energy storage performances

Flexible lead-free Na0.5Bi0.5TiO3-based film capacitor with stable energy storage performances