Energy Storage Market Research Articles

Realizing high-performance lithium-sulfur batteries via rational design and engineering strategies

Abstract Lithium-sulfur batteries (LSBs) have been of paramount interest due to their high specific energy, environmental benignity, and low-cost production as a promising candidate among the next generation of rechargeable batteries. Even they represent one of the most mature battery systems, the high discharging capacity and stable long cycling performance cannot be fully realized, especially under practical conditions, which hamper their entrance to the energy storage market in the near future. Solutions to unsolved issues that arise during the complex and multiphase conversion-type chemistry involved in LSBs are still being researched, including irreversible relocation of polysulfides, slow reaction kinetics, and low reliability of lithium anode. Achieving a scientific understanding of the current challenges toward the individual components in cells and the existing status of research strategies is vitally important to the development of LSBs. In this critical review, we attempt to summarize our current comprehension in this field, analyze and classify possible strategies to address the main concerns in the research on LSBs, and introduce design pathways for the further improvement of LSBs toward practical applications. Advanced methodology toward the synthesis of desirable host materials of the electrode with encapsulation effect via nanostructured design; the tailorable adsorption and catalysis property; chemical confinements function by covalent linking; modification of electronic structure, heteroatom doping, and defects are overviewed and highlighted. Methods for regulating salt anions, solvents, auxiliary additives in electrolytes, and the constructions of interlayers toward deployable separator and anode enabling interfacial protection; the establishment of novel electrode fabrication and functional batteries assembly systems technologies are discussed for the further development of viable LSBs. The strategies and perspectives outlined in this review will provide further research directions and help to achieve the aim of exploring high-performance LSBs technology with high energy density and long cycling stability.

The Renaissance of Liquid Metal Batteries

Next-generation batteries with long life, high-energy capacity, and high round-trip energy efficiency are essential for future smart grid operation. Recently, Cui et al. demonstrated a battery design meeting all these requirements—a solid electrolyte-based liquid lithium-brass/zinc chloride (SELL-brass/ZnCl2) battery. Such a battery design overcomes some inherent problems of conventional ZEBRA batteries and lithium ion batteries.

Review on operation mechanism and platform architecture of Distributed Energy Storage

“Distributed generation and Energy storage technology” has become a widely promoted operation mode to ensure reliable power supply when the distributed generation connected to the grid. In order to realize the unified regulation of energy storage, this paper summarizes the auxiliary operation function, market profit model and market operation mechanism of energy storage from three sides of generation, grid and users. The Distributed Energy Storage Operation Platform constructed through the strategy of “Hierarchical and Partitioned”. The good interaction between energy storage users and power grid realized through the comprehensive services of the platform. Several types of user categories and incentive mechanism under the interaction mode of grid and users sides summarized. Finally, the operation mechanism of distributed energy storage market summarized and prospected.

The Sodium-Ion Battery: Effect of Electrolyte Additives on the SEI Layer of Hard Carbon Anodes

Since their discovery, lithium-ion batteries (LIBs) have dominated the energy storage and power market due to their attractive attributes. However, LIBs cannot cope with the ever-growing energy demand and new alternatives must be explored. The low cost, and abundance of sodium, as well as its similar chemical properties to lithium, make the sodium-ion battery (SIB) a promising alternative for the future.1-5 SIBs often suffer from a short cycle lifespan, which is mainly attributed to the formation of an unstable solid electrolyte interphase (SEI) layer on the hard carbon anode surface. During the first cycle, the electrolyte solution is reduced, and its decomposition products form a passivation film (SEI) on the anode. Ideally, the SEI should protect the electrolyte from further decomposition during subsequent cycling, while being permeable to sodium ions. To reach this ideal situation, the employment of film-forming electrolyte additives in small amounts is necessary.6-11 In this study, in-operando electrochemical quartz crystal microbalance is used to monitor how additives affect the mass variation during the sodium intercalation/de-intercalation process. Mass spectrometry is further employed to identify and quantify the generated gaseous species during the initial SEI formation. After cycling, scanning electron microscopy and X-ray photoelectron spectroscopy are used to explore the additives effect on the SEI thickness and composition. A range of additives are considered including 1,3-propane sultone, succinonitrile and sodium-difluoro(oxalato)borate. The results of this study will be presented, along with suggestions for future research. Reference s : [1] P. K. Nayak, L. Yang, W. Brehm, P. Adelhelm, Angew. Chem. Int. Ed. 57 (2018) 102–120.[2] S. Roberts, E. Kendrick, Nanotechnol. Sci. Appl.11 (2018) 23-33.[3] H. Li, X. Zhang, Z. Zhao, Z. Hu, X. Liu, G. Yu, Energy Storage Mater. 26 (2020) 83–104.[4] J. Deng, W. B. Luo, S. L. Chou, H. K. Liu, S. X. Dou, Adv. Energy Mater. 8 (2018) 1–17.[5] L. Li, Y. Zheng, S. Zhang, J. Yang, Z. Shao, Z. Guo, Energy Environ. Sci., 11 (2018) 2310–2340.[6] G. Eshetu, M. Martinez-Ibañez, E. Sánchez-Diez, I. Gracia, L. Chunmei, L. M. Rodriguez-Martinez, T. Rojo, H. Zhang, M. Armand, Chem. Asian J. 13 (2018) 2770-2780.[7] M. Dahbi, T. Nakano, N. Yabuuchi, S. Fujimura, K. Chihara, K. Kubota, J.Y. Son, Y.T. Cui, H. Oji, S. Komaba, ChemElectroChem, 3 (2016) 1856–1867.[8] G. Yan, K. Reeves, D. Foix, Z. Li, C. Cometto, S. Mariyappan, M. Salanne, J.M. Tarascon, Adv. Energy Mater. 4 (2019) 36244–36251.[9] S. Komaba, W. Murata, T. Ishikawa, N. Yabuuchi, T. Ozeki, T. Nakayama, O. Atsushi, G. Kazuma, K. Fujiwara, Adv. Funct. Mater. 21 (2011) 3859-3867.[10] A. Bouibes, N. Takenaka, T. Fujie, K. Kubota, S. Komaba, M. Nagaoka, Appl. Mater. Interfaces. 10 (2018) 28525-28532.[11] M.A. Muñoz-Márquez, D. Saurel, J.L. Gómez-Cámer, M. Casas-Cabanas, E. Castillo-Martínez, T. Rojo, Adv. Energy Mater. 7 (2017) 1-31.

An Advanced Iron-Chromium Redox Flow Battery

Nowadays, the electricity generation cost using renewable resources has been reduced to such a low level that it is possible to replace most fossil fuel-based energy with renewables in the near future. However, the intermittent property with most renewables, such as solar and wind, requires vast amount, flexible and affordable energy storage products. None of the current widely used energy storage technologies can meet these requirements.An aqueous-based true redox flow battery has many unique advantages, such as long lifetime, safe, non-capacity decay, minimal disposal requirement, and flexible power and energy design. All these make it a great candidate for the vast renewable energy storage market. The key issue with this technology is the cost and availability of the energy-storage media. Due to the limited vanadium resources, it is very difficult for the vanadium-based redox flow battery to be widely used for fast-growing renewable energy storage market.Iron-chromium redox flow battery was invented by Dr. Larry Thaller’s group in NASA more than 45 years ago. The unique advantages for this system are the abundance of Fe and Cr resources on earth and its low energy storage cost. Even for a mixed Fe/Cr system, the electrolyte raw material cost can still be less than 10$/kWh. The major issue with this system is the continuous capacity decay due to hydrogen generation, which makes this system impractical for long-term operations.Here we report our recent results on this system. By using a special system design, the hydrogen generation level was largely reduced, down to less than 0.25% per full cycle. A capacity recovery system was successfully developed, which can compensate the system capacity loss due to hydrogen generation. More than 1000 cycles of operation have been carried out using a system with a kW-scale stack and 100 L electrolyte over a few months. Stable system capacity and stable continuous operation were successfully achieved.With these results, a containerized product is proposed. For a 20’ ISO container-sized product, the deliverable energy is 250 kWh, and the normal and maximum discharge powers are 25 and 50 kW respectively. The cost for such a product is lower than 80$/kWh, and the energy storage cost using this product is less than $0.02/kWh (assuming the product has 15 yr lifetime, and it operates 300 full cycle per year). With this energy storage cost, it is possible to achieve our ambitious 100% renewable energy goal in the near future.

In Operando Lithiation of Lithium Free Cathodes

Lithium and lithium-rich containing cathodes such as LiCoO2, LiFePO4, LiNixMnyCozO2, Li-rich anti-fluorite Li5FeO4 have dominated the portable battery energy storage market. Compounds without lithium in their lattice seldomly have been used as positive electrodes either due to incapability for reversible reactions or require metallic lithium metal electrode. These limitations have prevented the development of new positive electrodes to a larger extent in lithium-ion batteries. Examples of such materials are sulfur, vanadium oxides, FeS2, MnO2, FeF3, etc. However, these materials demonstrate tremendously high specific capacities, and high operating voltages, possibly realizing advanced next-generation batteries. To practically realize them, it is pertinent to address the lithiation strategies, namely pre-lithiation of the anode,blended cathodes, lithium additives, and film-forming additives. These methods result in modification of cell voltage on account of Li+ ion voids in the cathode, whereas pre-lithiation of anode compensates initial lithium consumption. Nevertheless, the pre-lithiation process is one of the unique techniques connected with the complicated, multistep, moisture-sensitive, expensive process, which is not feasible in large-scale applications.In situ lithiation of cathode or anode electrodes for the development of longer-lasting rechargeable batteries uses metallic lithium-electrode as a booster and reservoir. The presence of third reservoir electrode in the lithium-ion battery (LIB), i.e., metallic lithium, is brought into electrochemical reactions initially during the lithiation process and later as a booster to rejuvenise LIBs after the capacity fade on account of cycling. Here, we report the usage of V2O5 cathode with tailored silicon-carbon-graphite composite to fabricate high specific capacity and high energy-density LIBs. The tri-electrode system delivered a high initial charge specific capacity of 240 mAh g-1. After 100 cycles, re-boosting was provided, and at the end of 200th cycle the cell delivered a high average capacity of 140 mAh g-1. The tri-electrode system provided an initial high energy density of 960 Wh kg-1 and an average of 560 Wh kg-1 after 200 cycles. Using thermal signatures from multiple module calorimetry, the safety features of the proposed tri-electrode system were studied and compared to conventional LIBs. Using this novel concept of reservoir boosting would be of prime importance and value in space, healthcare, electric vehicles, UPS, grid-storage, etc. applications.

Correlating Transient Mechanical and Electrochemical Behaviors in Lithium Ion Batteries

Lithium-ion batteries (LiBs) represent a dominant technology in the current energy storage market. However, many aspects of these batteries are still poorly understood, and proper engineering of these aspects will lead to increased cycle life and performance parameters. In particular, the electrode - electrolyte interface is still an actively researched topic and is notoriously difficult to study. A new ultrasound acoustic characterization technique is introduced to probe the electrode/electrolyte interface in operando using signal amplitude analysis. This technique gives insight into lithium ion concentration accumulation and depletion at the electrode/electrolyte interface, and these findings are consistent with Dualfoil model simulations. Figure 1

Hybrid Redox Flow Cells with Enhanced Electrochemical Performance via Binderless and Electrophoretically Deposited Nitrogen-Doped Graphene on Carbon Paper Electrodes.

Hybrid redox flow cells (HRFC) are key enablers for the development of reliable large-scale energy storage systems; however, their high cost, limited cycle performance, and incompatibilities associated with the commonly used carbon-based electrodes undermine HRFC's commercial viability. While this is often linked to lack of suitable electrocatalytic materials capable of coping with HRFC electrode processes, the combinatory use of nanocarbon additives and carbon paper electrodes holds new promise. Here, by coupling electrophoretically deposited nitrogen-doped graphene (N-G) with carbon electrodes, their surprisingly beneficial effects on three types of HRFCs, namely, hydrogen/vanadium (RHVFC), hydrogen/manganese (RHMnFC), and polysulfide/air (S-Air), are revealed. RHVFCs offer efficiencies over 70% at a current density of 150 mA cm-2 and an energy density of 45 Wh L-1 at 50 mA cm-2, while RHMnFCs achieve a 30% increase in energy efficiency (at 100 mA cm-2). The S-Air cell records an exchange current density of 4.4 × 10-2 mA cm-2, a 3-fold improvement of kinetics compared to the bare carbon paper electrode. We also present cost of storage at system level compared to the standard all-vanadium redox flow batteries. These figures-of-merit can incentivize the design, optimization, and adoption of high-performance HRFCs for successful grid-scale or renewable energy storage market penetration.

Research on influencing factors of coal price based on improved principal component analysis and grey correlation method

As an important basic energy in China, the price fluctuation of coal is related to the operation of China’s coal market and the whole energy market and coal price analysis has always been the focus of the industry. By establishing an improved principal component-grey correlation analysis (PCA-GRA) model, the influencing factors of coal price were analyzed and tested one by one, and the influence degree of the influencing factors such as total coal production, total coal consumption, coal import and export volume, and world coal price on China’s coal price was studied. The results show that coal price fluctuation is greatly influenced by coal energy storage level and market environment level. In order to promote the development of coal industry, some suggestions are put forward.

Modeling Costs and Benefits of Energy Storage Systems

In recent years, analytical tools and approaches to model the costs and benefits of energy storage have proliferated in parallel with the rapid growth in the energy storage market. Some analytical tools focus on the technologies themselves, with methods for projecting future energy storage technology costs and different cost metrics used to compare storage system designs. Other tools focus on the integration of storage into larger energy systems, including how to economically operate energy storage, estimate the air pollution and greenhouse gas emissions effects of storage, or understand how policy and market rules influence storage deployment and operation. Given the confluence of evolving technologies, policies, and systems, we highlight some key challenges for future energy storage models, including the use of imperfect information to make dispatch decisions for energy-limited storage technologies and estimating how different market structures will impact the deployment of additional energy storage.

Clean energy transition in Mexico: Policy recommendations for the deployment of energy storage technologies

The adoption of a constitutional energy reform in 2013 in Mexico opened the door for private investment in the electricity sector and directed the country towards a clean energy transition. However, the expanding role of renewable energy poses new flexibility challenges for the Mexican power system. Even though energy storage technologies are one of the many solutions to add grid flexibility, they have not yet been implemented in Mexico and their consideration in new energy policies is very limited. Based on a comparative policy analysis between Mexico, the US and Germany, this paper seeks to provide policy recommendations to incentivise the deployment of energy storage technologies in Mexico. The main priority for Mexican policymakers should be to create a legal definition of energy storage and design clear market regulations. Mexico should also focus on funding demonstration projects of well-proven technologies and introducing financial incentives to accelerate investments in energy storage. Procurement targets are a key policy to create storage markets in the short term.

Role of Policy in Development of Business Models for Battery Storage Deployment: The California Case Study

California has been one of the early adopters of new energy storage technologies within the United States. The state has used multiple policy initiatives such as deployment targets, financial incentives, and market mechanism to facilitate such a market development. This motivates us to try to understand the various business models in the state and the minimum set of barriers that must be overcome for its successful deployment (and thereby development of the market). In our study, the former is achieved by assessing the various projects in the state, and the latter by creating a barrier-solution framework and verifying it by identifying the role of various policies/drivers in supporting various business models within California. We find that there are predominantly three business models in California: one for each Front-of-the-Meter, Behind-the-Meter, and Aggregated Behind-the-meter. We also find that at least one barrier from barrier categories associated with market demand and project economics along with all the barriers related to interconnection and market participation must be addressed for successful deployment of energy storage. Additionally, we recommend policy makers seeking to develop an energy storage market to start with developing Behind-the-meter market as it requires the least amount of intervention and then move to developing Front-of-the-meter market, and finally to aggregation of Behind-the-meter market.

Construction of Dual‐Carbon Co‐Modified LiFePO4 Nanocrystals via Microreactor Strategy for High‐Performance Lithium Ion Batteries

A facile and controllable dual‐carbon microreactor approach has been developed to prepare graphene and amorphous carbon co‐decorated LiFePO4 (LFP) nanocomposites (G/LFP@C). Physical characterizations demonstrate that the particle size of the restricted LFP crystals is ≈30–50 nm, which are well proportioned and well anchored on the surface of graphene and completely coated by the amorphous carbon layers. The electrochemical data demonstrate the impressive electrochemical performances of the G/LFP@C composite and its application potential as a cathode material of lithium ion batteries (LIBs). Particularly, the large specific capacity (161.3 mAh g−1 at 0.2 C), superior rate property (93.8 mAh g−1 at 20 C), and outstanding cycling stability (97.3% capacity retention over 1000 cycles at 10 C) are simultaneously realized for G/LFP@C because of the optimized electrochemical reaction kinetics with effective dual‐carbon co‐constructed conductive network and abundant active sites. It is believe that this work not only supplies unique in sights into the reasonable design of LFP materials for favorable property LIBs, but also holds great potential for the energy storage market.

(Invited) Polymer Electrolyte Membrane Water Electrolyzers – Current Challenges and Perspectives Beyond 2020

Hydrogen is largely considered the best means by which to store energy coming from renewable and intermittent power sources such as wind and solar. With the growing capacity of out-spread renewable energy sources surpassing the gigawatt range, a storage system of equal magnitude is required, such as the production of electrolytic hydrogen by water electrolysis. Consequently, we envision a rapid market penetration of water electrolyzers in the next years. Nevertheless, the deployment of current, commercially available electrolyzer stacks and systems is conceivable for the current initial period of energy transition and shall go over the next decades. However, electrolyzers still need transformation, rupturing from small, costly and low-efficiency units into game-change electrolyzers much larger than 10 MW, with efficiencies above 80%, power densities greater than 10 W/cm2, and demonstrated durability above 100.000 hours. To achieve these goals, fast and large R&D investment is necessary, strong commitment from government and society; all tied with focused and intensive international collaboration. Over the past 10 years, new companies and projects have appeared, with new leaders being consequently established in this growing “niche”. In this presentation I will show our latest R&D approaches; aiming to increase efficiency, improve durability, and reduce the investment/operating costs of electrolyzers to allow large market penetration of these systems. We believe that only through cutting-edge R&D and significant advancements; we will be able to ultimately establish “green” hydrogen as a commodity in the energy storage market, and contribute to our so much desired environmentally friendly hydrogen economy.

Multiagent-Based Energy Trading Platform for Energy Storage Systems in Distribution Systems With Interconnected Microgrids

In this article, an agent-based transactive energy (TE) trading platform to integrate energy storage systems (ESSs) into the microgrids’ energy management system is proposed. Using this platform, two different types of energy storage market models are proposed to promote local-level (within the microgrid) and communal- or global-level ESSs’ participation in the intra- and intermicrogrid TE markets. Also, a reinforcement learning algorithm known as simulated-annealing-based $Q$ -learning is used to develop bidding strategies for ESSs to participate in the TE markets. Besides energy trading, the proposed system also accounts for the losses caused by energy transactions between ESSs and microgrids using a complex current-tracing-based loss allocation method. The overall efficacy of the proposed energy market management system is demonstrated using a modified IEEE 123-bus distribution system with multiple microgrids and ESSs. Based on simulation results, it is observed that the proposed model can effectively reinforce the balance between the supply and the demand in the microgrids using the mix of local and global ESSs.

Quantifying Decay Rates of Electrochemically Active Species Using Microelectrode Voltammetry

The availability, abundance, and energy density of fossil resources have driven progress over the last century leading to dramatic improvements in quality of life worldwide. However, to avert catastrophic climate change, there is an increasingly urgent need to reduce carbon emissions without stifling economic growth. Deep decarbonization necessitates mass deployment of renewable technologies, such as wind and solar photovoltaic, to displace existing carbon-intensive electricity generation. Though increasingly inexpensive, the inherent difficulties in converting the intermittent output of renewable installations into reliable, dispatchable power sources represents an important constraint and motivates research into storage technologies to buffer the intermittency without significantly increasing the cost of electricity.There are several large-scale energy storage technologies available but all suffer some drawbacks. Pumped hydro storage, currently responsible for 99% of the energy storage market in the U.S., has high energy efficiency and is inexpensive with long cycle and calendar life; however, there have been few new installations in the U.S. due largely to the difficulty of permitting new sites, financing large projects, and meeting geographic requirements1,2. Redox flow batteries (RFBs) are an electrochemical technology that holds promise for long duration energy storage due to their location independence, lower capital cost, decoupled energy and power specifications, and inherent safety. The current state of the art RFBs employ vanadium as the active species which is relatively expensive. As system level costs decline, the cost of RFBs will approach materials cost and so finding less expensive materials if critical to reducing RFB price. Some redox active species used to store electricity in RFBs undergo decomposition due to residing outside the thermodynamic solvent stability window, optical sensitivity, or air sensitivity. These decay pathways consume active materials and reduce the lifetime of the RFB. Determining the kinetic parameters of this decomposition and quantifying the impact on system lifetime is the task we address here.Here, we demonstrate the utility of microelectrodes for quantifying rapid decay in electrochemical systems containing soluble redox active components. By holding a sufficiently reducing or oxidizing potential on a microelectrode, as compared to the equilibrium potential of the redox couple of interest, limiting currents can be continuously monitored without significantly altering the state-of-charge of the bulk solution. From this current, a concentration can be extracted and its time-dependent evolution can be fit to a general rate equation. As a model reaction, we evaluate the decay of permanganate, which is under consideration as a positive electrolyte material in alkaline aqueous RFBs3. Preliminary studies have shown permanganate auto reduces to manganate and oxygen, introducing a potential flammability hazard and decreasing the lifetime of RFBs4–6. A better understanding of the factors that influence this decay process will inform mitigation strategies. We find that the decay of permanganate is strongly dependent on supporting electrolyte pH. The decay order was found to approximate a second order with the rate constant near 40 M-1 min-1 in the least stable supporting salt concentrations and approaches zero in the most stable conditions. These numerically fit parameters are in close agreement with observed decomposition times and agree with parameters calculated using UV-vis spectroscopy. The talk will include development of the microelectrode technique, benchmarking with model compounds and UV-vis spectroscopy, and, finally, demonstration on a rapidly decaying model species, permanganate. We anticipate that the technique developed here can be applied to other systems experiencing similarly rapid decay that frustrates conventional methodologies.

In-situ preparation of LixSn-Li2O–LiF/reduced graphene oxide composite anode material with large capacity and high initial Coulombic efficiency

Anode materials with large capacity have a growing application due to the booming electric vehicle and energy storage market. However, the low initial Coulombic efficiency (ICE) and poor cycle stability hinder their commercial development. Herein, we investigate the effective and convenient method of preparing LixSn-Li2O–LiF/reduced graphene oxide (LixSn-Li2O–LiF/RGO, Li-GFTO) composite anode material with large capacity and high ICE. Firstly, the highly-dispersed fluorine-doped tin oxide and reduced graphene oxide (F–SnO2/RGO, GFTO) composite is in-situ synthesized by one-pot reflux method. The fluorine-doped SnO2 nanocrystals are uniformly anchored on graphene sheets. Secondly, the F–SnO2/RGO was lithiated by reacting with the lithium dissolved in the solution of biphenyl and 1,2-dimethoxyethane to get LixSn-Li2O–LiF/RGO composite. The Li2O and LiF will be formed and prevent the diffusion and coarsening of Sn and LixSn during cycling. Used as the anode material, the ICE of the LixSn-Li2O–LiF/RGO composite is as high as 97%. The composite anode material also shows high cycling stability. The residual capacity is as high as 992 mAhg−1 at 0.1 Ag-1 after 100 cycles, and the charge capacity retention is 99%. Most of all, the mild preparation condition promotes the mass production and practical application of tin-lithium alloy based composite anode materials.

Research on the Critical Issues for Power Battery Reusing of New Energy Vehicles in China

With the rapid development of new energy vehicles (NEVs) industry in China, the reusing of retired power batteries is becoming increasingly urgent. In this paper, the critical issues for power batteries reusing in China are systematically studied. First, the strategic value of power batteries reusing, and the main modes of battery reusing are analyzed. Second, the economic benefit models of power batteries echelon utilization and recycling are constructed. Finally, the economic benefits of lithium iron phosphate (LIP) battery and ternary lithium (TL) battery under different reusing modes are analyzed based on the economic benefit models. The results show that when the industrial chain is fully coordinated, LIP battery echelon utilization is profitable based on a reasonable scenario scheme. However, the multi-level echelon utilization is only practical under an ideal scenario, and more attention should be paid to the first level echelon utilization. Besides, the performance matching of different types of batteries has a great impact on the echelon utilization income. Thus, considering the huge potentials of China’s energy storage market, the design of automobile power batteries in the future should give due consideration to the performance requirements of energy storage batteries. Moreover, the TL battery could only be recycled directly, while the LIP has the feasibility of echelon utilization at present. At the same time, it will strengthen the cost advantage of the LIP battery, which deserves special attention.

Holey three-dimensional wood-based electrode for vanadium flow batteries

The vanadium flow battery (VFB) is widely regarded as one of the most reliable large-scale energy storage technologies due to its flexible design, long cycle life, and high safety. However, novel electrodes for VFBs with a well-suited structure by cost-effective manufacturing processes are still highly sought after to penetrate the growing energy storage market. Here, we demonstrate a holey three-dimensional (3D) wood-based electrode for VFBs, which was engineered by the facile perforation and carbonization of earth-abundant, low-cost, and sustainable wood. The 3D-wood electrode inherits the intrinsic, vertically-aligned channels (i.e. low tortuosity structure) of the original crude wood material, which provides fluent electrolyte transport paths in the flow battery system. Furthermore, small holes (approximately 1.3 ​mm) are drilled across the 3D-wood electrode in the perpendicular direction to connect the parallel channels, thereby enabling ion exchange and reducing flow resistance. The concentration polarization is significantly reduced during the charge and discharge process in VFB, due to these electrode modifications. The porous structure of the 3D-wood electrode, with a high specific surface area of 216.77 ​m2 ​g−1 and oxygen functional groups, provides sufficient reaction sites for vanadium cations to enhance the electrochemical reactivity of VFBs. The superior structure of the 3D-wood electrode ensures the feasibility in VFBs and offers a promising direction for developing flow battery electrodes through pore engineering of earth-abundant biomaterials.

Life cycle assessment of a vanadium flow battery

Battery storage technologies have been showing great potential to address the vulnerability of renewable electricity generation systems. Among the various options, vanadium redox flow batteries are one of the most promising in the energy storage market. In this work, a life cycle assessment of a 5 kW vanadium redox flow battery is performed on a cradle-to-gate approach with focus on the vanadium electrolytes, since they determine the battery’s storage capacity and can be readjusted and reused indefinitely. The functional unit is 1 kWh stored by the battery. The initial results show that the environmental hotspots reside mainly in the structural and material components of the battery, evidencing the need for alternative or recycled materials, preferably produced locally. Since the quantity of electrolytes determine the amount of storable electricity, an analysis was conducted on the variation of the impacts with the increase of storage capacity. An alternative scenario with reused electrolytes was also performed. Results show that with the increase of storage capacity, the contribution of the electrolytes to the impacts decrease significantly by stored kWh. In the reused electrolytes scenario, impacts were reduced mainly for the Acidification and Mineral, fossil and renewable resource depletion categories.