Life Research Articles

Robust asymmetric gel polymer electrolytes with 2D h-BN as protective layer for highly stable solid-state lithium metal batteries

Gel polymer electrolytes (GPEs) have emerged as a highly promising alternative to conventional liquid electrolytes for stable lithium-metal batteries (LIBs). However, their inherent poor mechanical properties and limited interfacial compatibility with lithium metal usually lead to unexpected growth of lithium dendrites, hindering commercial viability. Herein, an asymmetric polymer electrolyte with h-BN (HGPE) as protective layer was fabricated via a facile one-step coating strategy. Compared to pure GPE, the asymmetric polymer electrolytes exhibit significantly enhanced mechanical strength from 4.4 MPa to 7.4 MPa, effectively suppressing lithium dendrite growth. Furthermore, the HGPE improves interfacial compatibility with the anodes by preventing direct contact between GPE and lithium metals. The addition of h-BN also enhances the lithium-ion transfer number (tLi+), reaching 0.87 compared to 0.53 for pure GPE, attributed to the hindrance of anion movement by the protective layer. Consequently, the Li symmetric battery assembled with HGPE demonstrate exceptional long-term stability, maintaining performance over 1600 h at 0.1 mA cm−2. Furthermore, the assembled Li|LiFePO4 battery can deliver a high-capacity retention rate of 93.8 % after 500 cycles at room temperature, showcasing the promising potential of asymmetric polymer electrolytes for high-performance LMBs.

Influence of different causes on thermal runaway characteristic of LiFePO4 battery

To solve the current battery safety issues and accident investigation problems. Thermal runaway experiments triggered by nail penetration, hot box, flame heating and heating plate were carried out on a commercial 8 Ah pouch LiFePO4 battery. Recorded real-time phenomena, voltage and temperature. Then we discussed the TR process in the light of the latest mechanism study. The local TR is triggered by nail penetration within 3 s. The hot area above 700 °C and the spreading of internal TR was detected. LiFePO4 battery thermal runaway will generally emit white smoke, no fire. And it requires more attention to explosion risk. If the combustible gas is ignited, jet fire will appear, but the injection pressure is not extreme. Thermal runaway triggered by local heating is inconsistent with a voltage drop. A mapping method of thermal runaway parameters radar map is designed, which can indicate the danger degree of TR with shapes. Through comparison, some characteristics are obtained for the judgment of battery accident causes. This research can provide a basis for LFP battery safety evaluate and accident investigation.

In Situ Fabrication of High Ionic and Electronic Conductivity Interlayers Enabling Long-Life Garnet-Based Solid-State Lithium Batteries.

Garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) is a promising solid-state electrolyte (SSE) because of its fast ionic conduction and notable chemical/electrochemical stability toward the lithium (Li) metal. However, poor interface wettability and large interface resistance between LLZTO and Li anode greatly restrict its practical applications. In this work, we develop an in situ chemical conversion strategy to construct a highly conductive Li2S@C layer on the surface of LLZTO, enabling improved interfacial wettability between LLZTO and the Li anode. The Li/Li2S@C-LLZTO-Li2S@C/Li symmetric cell has a low interface impedance of 78.5 Ω cm2, much lower than the 970 Ω cm2 of a Li/LLZTO/Li cell. Moreover, the Li/Li2S@C-LLZTO-Li2S@C/Li cell exhibits a high critical current density of 1.4 mA cm-2 and an ultralong stability of 3000 h at 0.1 mA cm-2. When used in a LiFePO4 battery, the Li/Li2S@C-LLZTO/LiFePO4 battery exhibits a high initial discharge capacity of 150.8 mA h g-1 at 0.2 C without lithium storage capacity attenuation during 200 cycles. This work provides a novel and feasible strategy to address interface issues of SSEs and achieve lithium-dendrite-free solid-state batteries.

Recovery of iron phosphate and lithium carbonate from sulfuric acid leaching solutions of spent LiFePO4 batteries by chemical precipitation

The recycling of lithium and iron from spent lithium iron phosphate (LiFePO<sub>4</sub>) batteries has gained attention due to the explosive growth of the electric vehicle market. To recover both of these metal ions from the sulfuric acid leaching solution of spent LiFePO<sub>4</sub> batteries, a process based on precipitation was proposed in this study. Since ferric and ferrous ions coexisted in the leaching solution, all the ferrous ions were first oxidized to ferric ions by adding H<sub>2</sub>O<sub>2</sub> to the leaching solution. About 99% iron(III) was recovered as iron phosphate by adjusting the solution pH to 2 at 25 <sup>o</sup>C for 30 mins. After the precipitation of iron phosphate, the remaining Li(I) in the filtrate was recovered as lithium carbonate by precipitation with Na<sub>2</sub>CO<sub>3</sub> as a precipitant. Addition of acetone to the filtrate at room temperature greatly enhanced the precipitation percentage of Li(I). Moreover, solid Na<sub>2</sub>CO<sub>3</sub> was better than Na<sub>2</sub>CO<sub>3</sub> solution in precipitating Li(I). About 95% of lithium ions was recovered as carbonate precipitates under the optimum conditions: solution pH = 11, 3.0 molar ratio of solid Na<sub>2</sub>CO<sub>3</sub> to Li(I), 7/5(v/v) volume ratio of acetone to the filtrate, 25 <sup>o</sup>C, 300 rpm for 2 hrs.

Cyclic redox strategy for sustainable recovery of lithium ions from spent lithium iron phosphate batteries

The growth of spent lithium-ion batteries requires a green recycling method. This paper presents an innovative hydrometallurgical approach in light of redox flow batteries, which employed Fe3+/Fe2+ as regenerative redox mediator to selectively extract Li+ from LiFePO4. In contrast to the conventional method in which the oxidizer is disposable, the present scheme allows for the recycling of the oxidizer, which demonstrates the advantages of environmentally friendly, low cost and higher extraction rate, offering a novel approach to recycling spent batteries.

Computational Modelling of Heat Transfer through Aluminium Metal Foams for LiFePO4 Battery Cooling

Abstract: Temperature is crucial for battery pack durability and power. Folded fin and serpentine channel cooling methods are mostly used to cool the pack. However, fluid absorption during cooling can reduce capacity and cause downstream temperatures to be higher than upstream. Consistent cooling is vital to prevent temperature variation and increase battery pack lifespan. This work is concerned with the computational study of heat dissipation from open-cell aluminium metal foam for cooling LiFePO4 battery packs. The battery module consists of six pieces of pouch cell and three pieces of the aluminium foam heat sink. In the present study, aluminium foams are positioned between the LiFePO4 battery modules that are arranged in a vertical manner. Thermal interaction between the battery module and aluminum foam was studied. The effect of pore density on heat dissipation performance at different mass flow rates was explored. It has been discovered that aluminium foam with suitable porosity and pore density can efficiently cool the LiFePO4 battery pack. This paper provides a theoretical framework for designing a thermal management system for lithium- ion batteries using aluminium foam. Background: Metal foam cooling is an established technique for thermal management of Lithiumion batteries in electric vehicles. Objective:: The present study aims to analyze heat transfer through aluminium metal foams for vertically aligned LiFePO4 battery pack cooling. Methods: The Darcy extended Forchheimer (DEF) model examines fluid flow through metallic foams, using the local thermal non-equilibrium model to determine heat transfer. Results: The impact of the density of pores in the aluminium foam on the average wall temperature and temperature difference along the battery surface is determined. The variation of heat transfer of lithium-ion battery modules for different mass flow rates is also studied. Conclusion: The results indicate that utilizing aluminium foam as a heat transfer medium for battery modules significantly enhances their thermal management performance.

Analysis of polyanion single ion conductor based on preparation of gel electrolyte for lithium ion battery

Abstract This study achieved efficient preparation of polyanionic single ion conductors by selecting appropriate raw materials and controlling preparation conditions. The results show that the window stability of electrolytic gel with a wide ionic electrochemical conductor is 2-4.5 V and 0.74 lithium ion migration. Lithium iron phosphate battery (LFP) is the positive electrode, lithium metal is the negative electrode, and PVDF-HFP Pampsli ion is the electrolyte. When lithium salt is not added, the rated power of the battery is 125 mah·g-1, and the current density is 2 C. The battery has a range of more than 500 times. In the current high-density 5 C situation, it has a specific capacity of 100 mAh·g-1 and a stable cycling ability of over 300 cycles, while maintaining nearly 100% stable Colomb efficiency.

Soot formation and its hazards in battery thermal runaway

As an increasingly important solution for the energy industry, batteries are widely used in electric vehicles and energy storage systems. However, thermal runaway of batteries is a serious safety hazard. In this process, the materials in the battery undergo thermal decomposition and combustion, resulting in the formation of soot and other harmful byproducts and posing a significant threat to the environment and human health. In this work, LiFePO4 and ternary lithium batteries are selected as experimental subjects to comprehensively evaluate the soot hazard in the thermal runaway process. The LiFePO4 and ternary lithium battery soot samples exhibited a typical "core-shell" structure, with lattice spacings ranging between 0.36-0.46 and 0.35–0.46 nm, respectively. The surfaces of these materials are covered with functional groups, including C–C, C–O, and O–H bonds. Soot samples taken from the thermal runaway of ternary lithium batteries also contain O–CO and π bonds, consistent with the functional groups in wood soot. Through EDS and XPS characterization, it is evident that the LiFePO4 battery soot contains C, O, Li, F, P, and Fe, while the ternary lithium battery soot, in addition to these elements, also contains Ni, Co, and Mn. The battery soot samples exhibited significant cytotoxicity to human cells, such as lung cells (MRC-5) and neural cells (SH-SY5Y). With high concentrations of soot, the survival rate of lung cells and nerve cells is low. Compared to wood soot, battery soot causes greater damage to human lungs and neural cells. The research in this work contributes to a better understanding of the hazardous characteristics of soot in battery thermal runaway and its potential threats to human health, offering a crucial reference for enhancing battery safety and emergency responses.

Research on the capacity allocation of composite energy storage systems for hybrid ships

Abstract Aiming at the problem of unstable output power fluctuation of the dredger during operation, a composite energy storage system consisting of lithium iron phosphate battery and supercapacitor is introduced to smooth out the power fluctuation. Considering the configuration cost, operation and maintenance cost of the energy storage system, the capacity optimization model of the composite energy storage system is established with the average daily cost as the objective function, and with the system power balance, the charge state of the energy storage system, and the rated power as the constraints. The optimal capacity is solved by using the modified artificial fish swarm algorithm (MAFSA). The final results show that MAFSA reduces the capacity of the battery and the supercapacitor by 6.9% and 9.9%, respectively, and reduces the average daily cost of the system by 13.5%. Meanwhile, the capacity-optimized energy storage system enables the generator set to work in the optimal operating range, which reduces its output power fluctuation, improves its efficiency, and reduces fuel consumption and pollutant emission.

Green and high-yield recovery of phosphorus from municipal wastewater for LiFePO4 batteries

The rapidly growing demand for lithium iron phosphate (LiFePO4) as the cathode material of lithium–ion batteries (LIBs) has aggravated the scarcity of phosphorus (P) reserves on Earth. This study introduces an environmentally friendly and economical method of P recovery from municipal wastewater, providing the P source for LiFePO4 cathodes. The novel approach utilizes the sludge of Fe-coagulant-based chemical P removal (CPR) in wastewater treatment. After a sintering treatment with acid washing, the CPR sludge, enriched with P and Fe, transforms into purified P–Fe oxides (Fe2.1P1.0O5.6). These oxides can substitute up to 35% of the FePO4 reagent as precursor, producing a carbon-coated LiFePO4 (LiFePO4/C) cathode with a specific discharge capacity of 114.9 mA·h·g−1 at 0.1 C (C represents current density, 1 C equaling 170 mA·g−1) (C), and cycle stability of 99.2% after 100 cycles. The enhanced cycle performance of the as-prepared LiFePO4/C cathode may be attributed to the incorporations of impurities (such as Ca2+ and Na+) from sludge, with improved stability of crystal structure. Unlike conventional P-fertilizers, this P recovery technology converts 100% of P in CPR sludge into the production of value-added LiFePO4/C cathodes. The recovered P from municipal wastewater can meet up to 35% of the P demand in the Chinese LIBs industry, offering a cost-effective solution for addressing the pressing challenges of P scarcity.

The aging pattern of lithium-ion batteries based on experiments at different temperatures

Abstract In this paper, we take an 18650-type LiFePO4 battery as the research object to investigate the aging mechanism of Li-ion batteries at different temperatures. The aging tests are conducted at 25°C, 35°C and 45°C. The results show that elevating the operating temperature can improve the cycle life of Li-ion batteries. The aging mechanism was analyzed by incremental capacity and electrochemical impedance spectrum analysis. The following conclusions were obtained: the aging mechanism of lithium-ion batteries mainly includes loss of lithium inventory, loss of active material, and conductivity loss, among which loss of lithium inventory and loss of active material are the main causes of Li-ion battery aging, and the contribution of conductivity loss is the smallest. Further analysis of the causes of battery aging by disassembling and testing the aging electrode sheet SEM and TEM shows that the aging of Li-ion battery is manifested by the rupture of graphite particles, the generation of SEI layer and lithium dendrite, and increasing the temperature can ease the rupture of graphite particles and the generation of lithium dendrite, thus improving the cycle life of the battery.

Experimental investigation on the effects of natural convection on cylindrical LiFePO4 battery module for energy storage application

AbstractThe experiments with a LiFePO4 battery pack operating at room temperature and with various charge and discharge rates to analyze its durability are described in this study. At a temperature of 23°C with natural convection, the thermal performance of a cylindrical (LFP) battery is experimentally studied. In this study, the battery is fully charged. After reaching 14.6 V, the battery is charged at a current of 4.8 A for 10 min to allow for stabilization. The battery is then depleted at 4.8 A until its voltage hits 10.5 V, followed by an additional 10‐min resting time. The processes reached their highest and lowest temperatures, respectively, were 29°C and 22°C. The battery is charged for a total of 46.877 Ampere‐hours (Ah) during the course of the 10‐h operation at a constant current of 4.8 A. Similar to this, a 10‐h discharge operation is carried out with a constant current of 4.8 A, yielding a discharge of 47.207 Ah. The processes reached their highest and lowest temperatures, respectively, were 36°C and 24°C. Another possibility is to charge the battery at a steady 24 A until the voltage reaches 14.6 V, then let it rest for 10 min, a further 10‐min rest period is added after it is discharged at 24 A until its voltage hits 10.5 V. After 5 h of charging at 24 A, the capacity is 46.958 Ah, and after 5 h and 47.51 min of discharging at 24 A, the capacity is 47 Ah. The processes reached their highest and lowest temperatures, respectively, were 49°C and 33°C.

Thermal Behavior of a Cylindrical 18650 LiFePO₄ Battery during Charge and Discharge Cycles

Thermal Behavior of a Cylindrical 18650 LiFePO₄ Battery during Charge and Discharge Cycles

Reuse of Lithium Iron Phosphate (LiFePO4) Batteries from a Life Cycle Assessment Perspective: The Second-Life Case Study

As of 2035, the European Union has ratified the obligation to register only zero-emission cars, including ultra-low-emission vehicles (ULEVs). In this context, electric mobility fits in, which, however, presents the critical issue of the over-exploitation of critical raw materials (CRMs). An interesting solution to reduce this burden could be the so-called second life, in which batteries that are no longer able to guarantee high performance in vehicles are used for other applications that do not require high performance, such as so-called stationary systems, effectively avoiding new over-exploitation of resources. In this study, therefore, the environmental impacts of second-life lithium iron phosphate (LiFePO4) batteries are verified using a life cycle perspective, taking a second life project as a case study. The results show how, through the second life, GWP could be reduced by ‒5.06 × 101 kg CO2 eq/kWh, TEC by ‒3.79 × 100 kg 1.4 DCB eq/kWh, HNCT by ‒3.46 × 100 kg 1.4 DCB eq/kWh, ‒3.88 × 100 m2a crop eq/kWh, and ‒1.12 × 101 kg oil eq/kWh. It is further shown how second life is potentially preferable to other forms of recycling, such as hydrometallurgical and pyrometallurgical recycling, as it shows lower environmental impacts in all impact categories, with environmental benefits of, for example, ‒1.19 × 101 kg CO2 eq/kWh (compared to hydrometallurgical recycling) and ‒1.50 × 101 kg CO2 eq/kWh (pyrometallurgical recycling), ‒3.33 × 102 kg 1.4 DCB eq/kWh (hydrometallurgical), and ‒3.26 × 102 kg 1.4 DCB eq/kWh (pyrometallurgical), or ‒3.71 × 100 kg oil eq/kWh (hydrometallurgical) and ‒4.56 × 100 kg oil eq/kWh (pyrometallurgical). By extending the service life of spent batteries, it may therefore be possible to extract additional value while minimizing emissions and the over-exploitation of resources.

Study on the fire extinguishing effect of compressed nitrogen foam on 280 Ah lithium iron phosphate battery

This study conducted experimental analyses on a 280 Ah single lithium iron phosphate battery using an independently constructed experimental platform to assess the efficacy of compressed nitrogen foam in extinguishing lithium-ion battery fires. Based on theoretical analysis, the fire-extinguishing effects of compressed nitrogen foam at different outlet pressures from foam mixture tanks were analyzed, examining factors such as battery surface temperature, flame temperature, and thermal weight loss. The results indicate that the compressed nitrogen foam can extinguish the open flame of the battery in 14 s at 0.7 MPa, with the battery's surface temperature dropping by approximately 11 % before and after the application of the extinguishing agent. Compared with other commonly used extinguishing agents, the compressed nitrogen foam demonstrates superior extinguishing efficiency, but its cooling efficiency is somewhat lower. At pressures ranging from 0.4 to 0.6 MPa, the foam displays prolonged drainage time and sustained cooling effects, rendering it more suitable for lithium-ion battery fire scenarios. To address the issue of reduced cooling performance during later stages of fire suppression by compressed nitrogen foam, an intermittent injection approach has been proposed to effectively preserve its cooling efficacy.

Towards robust state estimation for LFP batteries: Model-in-the-loop analysis with hysteresis modelling and perspectives for other chemistries

The accurate estimation of a battery’s state of charge (SOC) is critical in battery management systems for various applications. Lithium Iron Phosphate (LFP) batteries, preferred for their long cycle life, cost efficiency, and enhanced safety, have emerged as favourable choices for stationary storage. Yet, they still face challenges in precise SOC estimation due to the flatness and hysteresis of their open circuit voltage. Addressing this, our study integrates a hysteresis model into a third-order battery model for BMS controlling a stationary storage system in frequency containment reserve (FCR) application. We analysed three advanced SOC estimation techniques — extended Kalman filter (EKF), dual unscented Kalman filter (DUKF), and particle filter (PF) — with the hysteresis model using a model-in-the-loop (MiL) toolchain. Performance testing under a 48-hour FCR load profile showed EKF with a 4% error, DUKF achieving the best result with a 1.1% error, and PF’s performance varying between 2.9% and 4% depending on particle count. Robustness tests against initialization and current sensor errors under an 8hr profile revealed DUKF maintained a 2% error boundary irrespective of the error introduced, highlighting the hysteresis model’s effectiveness. Broadening the scope, the study also explores extending the method to other lithium-ion chemistries.

Coconstruction of Supramolecular Lithium-Conducting Cross-Linked Networks Based on PVDF and Triblock Polymer Nanomicrosphere Solid-State Polymer Electrolytes for Lithium-Metal Batteries.

Uneven lithium plating and low ionic conductivity currently impede the realization of high-capacity rechargeable lithium metal batteries. And the conventional poly(ethylene oxide) (PEO) solid-state electrolytes are unsuitable for high-energy-density Li anode applications due to their low lithium-ion transference number and high reactivity with Li metal, leading to detrimental dendrite formation and potentially hazardous exothermic reactions with the electrolyte. In this study, we employ a supramolecular approach to develop a novel polymer solid-state electrolyte based on poly(vinylidene fluoride) (PVDF) and a novel triblock polymer nanomicrosphere, (poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone), (PCL-PEG-PCL). The abundance of carbonyl and ether-oxygen functional groups in PCL-PEG-PCL enhances the lithium coordination environment within the polymer solid-state electrolyte. Additionally, the original C-F moieties of PVDF form hydrogen bonds with C-H and terminal hydroxyl groups in PCL-PEG-PCL, collectively creating a multichannel fast Li+-conducting supramolecular cross-linked network. The resulting electrolyte demonstrates a high ionic conductivity of 1.4 × 10-3 S cm-1 and an extended electrochemical window of 5.2 V. Moreover, the electrolyte exhibits a high lithium-ion transference number (tLi+ = 0.63) at room temperature and exhibits excellent interfacial compatibility with the lithium metal anode. For the resulting electrolyte utilized in LiFePO4 batteries, the capacity retention of the cells assembled with this electrolyte exceeds 91.3% after 1000 cycles at 25 °C and 2 C (0.281 mA cm-2).

Toward Sustainable Lithium Iron Phosphate in Lithium‐Ion Batteries: Regeneration Strategies and Their Challenges

AbstractIn recent years, the penetration rate of lithium iron phosphate batteries in the energy storage field has surged, underscoring the pressing need to recycle retired LiFePO4 (LFP) batteries within the framework of low carbon and sustainable development. This review first introduces the economic benefits of regenerating LFP power batteries and the development history of LFP, to establish the necessity of LFP recycling. Then, the entire life cycle process and failure mechanism of LFP are outlined. The focus is on highlighting the advantages of direct recycling technology for LFP materials. Directly regenerating LFP materials is a very promising solution. Directly regenerating spent LFP (S‐LFP) materials can not only protect the environment and save resources, but also directly add lithium atoms to the vacancies of missing lithium atoms to repair S‐LFP materials. At the same time, simply supplementing lithium to repair S‐LFP simplifies the recovery process and improves economic benefits. The status of various direct recycling methods is then reviewed in terms of the regeneration process, principles, advantages, and challenges. Additionally, it is noted that direct recycling is currently in its early stages, and there are challenges and alternative directions for its development.

In-situ oxidation for selective lithium extraction from spent LiFePO4 cathodes by low acid dosage

Recovery of lithium from spent lithium iron phosphate batteries is crucial to alleviating the storage of lithium. This study proposes a method for the selective recovery of lithium from spent lithium iron phosphate battery cathodes using a leaching system of H2SO4 and H2O2. Efficient and selective lithium recovery was achieved through in-situ oxidation of lithium iron phosphate driven by a low acid dosage, and the mechanism of selective lithium recovery was investigated by precipitation experiments of Fe2+ and PO43−. The shrinking core model was used for the kinetic analysis of the leaching process, and the results suggested that the leaching process was controlled by the internal diffusion of the product layer. Moreover, essential leaching parameters such as acid concentration, H2SO4 dosage, H2O2 dosage, leaching time, and leaching temperature were systematically investigated. The results showed that the leaching rate of Li reached 97.95 % along with a selectivity of 99.60 %, which meets the standard of the battery-grade Li2CO3, while the leaching rate of both Fe and P was less than 1 %.

Experimental study on flame morphology, ceiling temperature and carbon monoxide generation characteristic of prismatic lithium iron phosphate battery fires with different states of charge in a tunnel

Lithium-ion battery (LIB) fire in a tunnel can generate a high-temperature environment, massive toxic and harmful smoke in a short period. This work carried out a series of thermal runaway (TR) experiments on large prismatic lithium cells in a model tunnel. Results showed that the flame height of LIBs with above 50 % SOC was above 40 cm for much time of the stage (Ⅰ) and (Ⅱ). The average flame height is further proposed to quantify the flame profile at different phases. The greater the SOC was, the higher the ceiling temperature and peak CO concentration were also relatively. For example, while decreasing the distance to the fire source from 0 m to -0.7 m, the peak ceiling temperature of 25 Ah batteries with 100 % SOC decreases from 309 °C to 118 °C, with a decay rate of 62 %. The CO concentration showed a comparable variation pattern to the tunnel ceiling temperature. Finally, a dimensionless relationship was employed to describe the ceiling temperature decay. Meanwhile, the ceiling maximum temperature rise for different capacity battery fires in a tunnel was integrated into a relational correlation. The study results are expected to further understand the battery fire hazards in tunnel.