A degradable membrane based on lignin-containing cellulose for high-energy lithium-ion batteries

Regulating Zn deposition via an ion-sieving, nanoporous cellulose separator for high performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs), one of the most promising renewable energy storage devices, are largely impeded by the disreputable cycling stability in its large-scale application as a result of the undesirable Zn dendrites growth and the side reactions. In this context, a carboxylate (-COO-) anionic group functionalized cellulose nanofibrils separator (A-CNF) with nanoporous structure and ion-sieving effect is developed to realize a stable Zn anode without dendrites and by-products. An increased Zn2+ transference number and uniform Zn deposition can be achieved through the electrostatic adsorption between -COO- and Zn2+. More importantly, the synergistic effect between -COO- and hydroxyl group (-OH) in the cellulose nanofibrils separator inhibits the occurrence of side reactions caused by SO42- and free water molecules. As a result, the nanoporous separator consisting of carboxylated cellulose nanofibrils enables Zn anode with high stability and utilization, exhibiting a stable cycling life for 950 h in Zn//Zn cell and an admirable coulombic efficiency of 98.9 % after 300 cycles in Zn//Cu cell. The assembled Zn//MnO2 full cell with the nanoporous cellulose nanofibrils-based separator shows exceptional cyclability and capacity retention after 1000 cycles. This work provides a valuable and practical separator for high performance AZIBs, which might spur its practical application.

Eco-friendly and strong lignin-containing microfibrillated cellulose films for high-performance separators of aqueous zinc batteries

Aqueous zinc-ion batteries have gained significant interest, offering several distinct advantages over conventional lithium-ion batteries owing to their compelling low cost, enhanced battery safety, and excellent environmental friendliness. Nevertheless, the unfortunate growth of zinc dendrites during cycling leads to poor electrochemical performance of zinc batteries, primarily attributed to the diminished wet mechanical properties and limited electrolyte uptake of existing commercial separators. Herein, a bio-based separator was developed from sustainable resources using natural polymers derived from wood pulp to replace fossil-based polyolefin separators. The inherent hydrophilicity and swelling ability of cellulose fibers provide separators with superior electrolyte wettability and uptake. Notably, the structural reinforcement provided by lignin, especially after hot pressing, enhances the separator's wet mechanical integrity and performance during battery cycling. These improvements contribute to the separator's more stable electrochemical performance and improved ion transport properties. Separators composed of lignin-rich microfibrillated cellulose fibers showed superior dimensional stability under heat compared to Celgard, ensuring higher thermal safety and enhanced performance of aqueous zinc-ion batteries. Our results reveal the great potential of lignin-rich cellulose-based separators for future zinc-ion batteries.

Sapiential battery systems: beyond traditional electrochemical energy

As indispensable energy-storage technology in modern society, batteries play a crucial role in diverse fields of 3C products, electric vehicles, and electrochemical energy storage. However, with the growing demand for future electrochemical energy devices, lithium-ion batteries as an existing advanced battery system face a series of significant challenges, such as time-consuming manual material screening, safety concerns, performance degradation, non-access in the off-grid state, poor environmental adaptability, and pollution from waste batteries. Accordingly, incorporating the characteristics of sapiential life into batteries to construct sapiential systems is one of the most engaging tactics to tackle the above issues. In this review, we introduce the concept of sapiential battery systems and provide a comprehensive overview of their core sapiential features, including materials genomics, non-destructive testing, self-healing, self-sustaining capabilities, temperature adaptation, and degradability, which endow batteries with higher performance and more functions. Moreover, the possible future research directions on sapiential battery systems are deeply discussed. This review aims to offer insights for designing beyond traditional electrochemical energy, meeting broader application scenarios such as ultra-long-endurance electric vehicles, wide-temperature energy storage, space exploration, and wearable electronic devices.

Recent advance on lignin-containing nanocelluloses: The key role of lignin

Nanocelluloses (NCs) isolated from lignocellulosic resources usually require harsh chemical pretreatments to remove lignin, which face constraints such as high energy consumption and inefficient resource utilization. An alternative strategy involving the partial retention of lignin can be adopted to endow NCs with better versatility and functionality. The resulting lignin-containing nanocelluloses (LNCs) generally possess better mechanical property, thermal stability, barrier property, antioxidant activity, and surface hydrophobicity than lignin-free NCs, which have attracted extensive interest as a promising green nanomaterial for numerous applications. This review provides a comprehensive overview of the recent advances in the preparation, properties, and food application of LNCs. The effect of residual lignin on the preparation and properties of LNCs is discussed. Furthermore, the key roles of lignin in the properties of LNCs, including particle size, crystalline structure, dispersibility, thermal, mechanical, antibacterial, rheological and adhesion properties, are summarized comprehensively. Furthermore, capitalizing on their dietary fiber and nanostructure properties, the food applications of LNCs in the forms of films, gels and emulsions are also discussed. Finally, the challenges and opportunities regarding the development of LNCs are provided.

A bio-based functional separator enables dendrite-free anodes in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have garnered considerable interest as potential solutions for large-scale energy storage systems, owing to their cost-effectiveness and high safety. Nonetheless, the development of AZIBs is hindered by significant challenges associated with dendrite growth and side reactions on Zn anodes. Here, a bio-based separator derived from cellulose was developed for the dendrite-free anode in AZIBs. In addition, the separator is notable for its ultra-low cost and biodegradability in contrast to the commonly used commercial glass fiber (GF) separators. The mechanical strength of the separator is enhanced by the cross-linking of hydrogen bonds, effectively inhibiting dendrite growth. The zinc-philic groups facilitate better binding to Zn2+, resulting in uniform nucleation and deposition. The hydrophilic groups aid in trapping water molecules, thereby preventing side reactions of the electrolyte. The Zn||Zn symmetric cell with this separator can sustain a long cycle life for over 800 h, indicating stable Zn2 + plating and stripping with suppressed dendrite growth. Concurrently, the assembled Zn||VO2 full batteries exhibited a capacity retention rate of 61.87% after 1,000 cycles at 1 A g-1 with an initial capacity of 140 mAh g-1. This work highlights a stable, economical, and eco-friendly approach to the design of bio-based separators in AZIBs for sustainable energy storage systems.

Halloysite nanotubes enhanced polyimide/oxidized-lignin nanofiber separators for long-cycling lithium metal batteries

The high energy density and robust cycle properties of lithium-ion batteries contribute to their extensive range of applications. Polyolefin separators are often used for the purpose of storing electrolytes, hence ensuring the efficient internal ion transport. Nevertheless, the electrochemical performance of lithium-ion batteries is constrained by its limited interaction with electrolytes and poor capacity for cation transport. This work presents the preparation of a new bio-based nanofiber separator by combining oxidized lignin (OL) and halloysite nanotubes (HNTs) with polyimide (PI) using an electrospinning technique. Analysis was conducted to examine and compare the structure, morphology, thermal characteristics, and EIS of the separator with those of commercially available polypropylene separator (PP). The results indicate that the PI@OL and PI-OL@ 10 % HNTs separators exhibit higher lithium ion transference number and ionic conductivity. Moreover, the use of HNTs successfully impeded the proliferation of lithium dendrites, hence exerting a beneficial impact on both the cycle performance and multiplier performance of the battery. Consequently, after undergoing 300 iterations, the battery capacity of LiFePO4|PI-OL@ 10 % HNTs|Li stays at 92.1 %, surpassing that of PP (86.8 %) and PI@OL (89.6 %). These findings indicate that this new bio-based battery separator (PI-OL@HNTs) has the great potential to serve as a substitute for the commonly used PP separator in lithium metal batteries.

Eco-Friendly Lithium Separators: A Frontier Exploration of Cellulose-Based Materials

Lithium-ion batteries, as an excellent energy storage solution, require continuous innovation in component design to enhance safety and performance. In this review, we delve into the field of eco-friendly lithium-ion battery separators, focusing on the potential of cellulose-based materials as sustainable alternatives to traditional polyolefin separators. Our analysis shows that cellulose materials, with their inherent degradability and renewability, can provide exceptional thermal stability, electrolyte absorption capability, and economic feasibility. We systematically classify and analyze the latest advancements in cellulose-based battery separators, highlighting the critical role of their superior hydrophilicity and mechanical strength in improving ion transport efficiency and reducing internal short circuits. The novelty of this review lies in the comprehensive evaluation of synthesis methods and cost-effectiveness of cellulose-based separators, addressing significant knowledge gaps in the existing literature. We explore production processes and their scalability in detail, and propose innovative modification strategies such as chemical functionalization and nanocomposite integration to significantly enhance separator performance metrics. Our forward-looking discussion predicts the development trajectory of cellulose-based separators, identifying key areas for future research to overcome current challenges and accelerate the commercialization of these green technologies. Looking ahead, cellulose-based separators not only have the potential to meet but also to exceed the benchmarks set by traditional materials, providing compelling solutions for the next generation of lithium-ion batteries.

Exploitation of function groups in cellulose materials for lithium-ion batteries applications

Cellulose, an abundant and eco-friendly polymer, is a promising raw material to be used for preparing energy storage devices such as lithium-ion batteries (LIBs). Despite the significance of cellulose functional groups in LIBs components, their structure-properties-application relationship remains largely unexplored. This article thoroughly reviews the current research status on cellulose-based materials for LIBs components, with a specific focus on the impact of functional groups in cellulose-based separators. The emphasis is on how these functional groups can enhance the mechanical, thermal, and electrical properties of the separators, potentially replacing conventional non-renewal material-derived components. Through a meticulous investigation, the present review reveals that certain functional groups, such as hydroxyl groups (-OH), carboxyl groups (-COOH), carbonyl groups (-CHO), ester functions (R-COO-R'), play a crucial role in improving the mechanical strength and wetting ability of cellulose-based separators. Additionally, the inclusion of phosphoric group (-PO3H2), sulfonic group (-SO3H) in separators can contribute to the enhanced thermal stability. The significance of comprehending the influence of functional groups in cellulose-based materials on LIBs performance is highlighted by these findings. Ultimately, this review explores the challenges and perspectives of cellulose-based LIBs, offering specific recommendations and prospects for future research in this area.

Pure cellulose nanofiber separator with high ionic conductivity and cycling stability for lithium-ion batteries

Conventional polyolefin separators are constrained by poor electrolyte wettability, inferior thermal stability, and low ionic conductivity, which seriously restrict their application in high-performance lithium-ion batteries (LIBs). Herein, cellulose nanofiber (CNF) as the matrix and tert-butyl alcohol (TBA) as the dispersion medium were used to prepare the pure CNF separators for LIBs by a facile filtration method. The effects of the drying temperature on the pore structure, electrolyte wettability, mechanical properties, thermal stability, and ionic conductivity of the separators were comprehensively investigated. The results showed that the freeze-dried separator at -80 °C with TBA as the dispersion medium (TBA-FD) had the best overall performance, with the porosity and electrolyte uptake up to 70.8 % and 296 %, respectively, as well as the ionic conductivity up to 1.90 mS/cm. The CNF separators had no apparent thermal shrinkage at 160 °C, illustrating good thermal stability. Moreover, the LiFePO4/lithium metal battery assembled with the TBA-HD (tert-butyl alcohol as the dispersion medium for heat-drying at 80 °C) and TBA-FD separators displayed superior cycling stability (with a capacity retention rate up to 97.5 % and 96.4 %, respectively) and rate performance. The pure CNF separators with good performance prepared by the facile method are greatly promising for high-performance LIBs.

Study on cellulose nanofibers/aramid fibers lithium-ion battery separators by the heterogeneous preparation method

In this study, a heat-resistant and high-wettability lithium-ion batteries separator (PI-CPM-PI) composed of cellulose nanofibers (CNF) and aramid fibers (PMIA chopped fiber/PPTA pulp) with the reinforced concrete structure was fabricated via a traditional heterogeneous paper-making process. CNF played crucial roles in optimizing the pore structure and improving the wettability of PI-CPM-PI separator. The effects of composition on separator properties were investigated and the results indicated that the optimal compositions were 0.5 wt% CNF, 0.5 wt% PMIA chopped fiber/PPTA pulp (ratio of 5:5), 0.05 wt% diatomite and 1.5 wt% polyimide. Relevant tests demonstrated that the performance advantages of PI-CPM-PI separators were exhibited at the wettability and thermal stability compared to the commercial separator (PP). Additionally, batteries assembled with PI-CPM-PI separators showed excellent electrochemical and cycling performance (ionic conductivity of 1.041 mS.cm^-1, the first discharge capacity of 158.2 mAh.g^-1 at 0.2C and capacity retention ratio of 99.76 % after 100 cycles).