High energy density in ultra-thick and flexible electrodes enabled by designed conductive agent/binder composite

Thick electrodes can increase incorporation of active electrode materials by diminishing the proportion of inactive constituents,improving the overall energy density of batteries.However,thick electrodes fabricated using the conventional slurry casting approach frequently exhibit an exacerbated accumulation of carbon additives and binders on their surfaces,invariably leading to compromised electrochemical properties.In this study,we introduce a designed conductive agent/binder composite synthesized from carbon nanotube and polytetrafluoroethylene.This agent/binder composite facilitates production of dry-process-prepared ultra-thick electrodes endowed with a three-dimensional and uniformly distributed percolative architecture,ensuring superior electronic conductivity and remarkable mechanical resilience.Using this approach,ultra-thick LiCoO_(2)(LCO) electrodes demonstrated superior cycling performance and rate capabilities,registering an impressive loading capacity of up to 101.4 mg/cm^(2),signifying a 242% increase in battery energy density.In another analytical endeavor,time-of-flight secondary ion mass spectroscopy was used to clarify the distribution of cathode electrolyte interphase(CEI) in cycled LCO electrodes.The results provide unprecedented evidence explaining the intricate correlation between CEI generation and carbon distribution,highlighting the intrinsic advantages of the proposed dry-process approach in fine-tu ning the CEI,with excellent cycling performance in batteries equipped with ultra-thick electrodes.

Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.

Comparative study of mining methods for reserves beneath end slope in flat surface mines with ultra-thick coal seams

The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.

Suitable layout of gate roads related to slice mining in an ultra-thick unstable coal seam

We determined a suitable gate road layout in slice mining in an ultra-thick unstable coal seam,using theoretical analysis and numerical calculations.Based on plasticity theory in terms of limiting equilibrium,the width of chain pillar in the upper slice was calculated to be 18 m.The stress distribution in the chain pillar after the upper slice was mined out was described with numerical simulation.The extent of the effect of stress on the upper chain pillar on the lower solid coal was obtained on the basis of an elastic solution of a distributed force loaded on a half-plane.Three layout designs for lower gate roads were proposed and a stability factor was introduced to analyze the stability of the lower pillar with numerical calculation.Gate road translation was determined as the most suitable layout method,which maximizes the extraction rate on the basis of the pillar stability.

An empirical model for high energy density lithium-(ion)batteries with ultra-thick electrodes

Increasing the electrode thickness is a significant method to decrease the weight and volume ratio of the inactive components for high energy density of the devices.In this contribution,we extracted a repeating unit in the configurations and establish the empirical energy density model based on some assumptions.In this model,the effects of the electrode thickness on the energy density for lithium-ion batteries(LIBs),lithium metal batteries(LMBs),and anode-free lithium batteries(ALBs)are evaluated quantitively with the current parameters of the batteries.The results demonstrate that the structure evolutions from LIBs,LMBs to ALBs with the reduction of the anode weight contribution,the energy density can be well improved exactly.While the increase of the thickness of the electrode provide another route to furthe r enhance the energydensity by decreasing the weight contribution of inactive materials;meanwhile the effects for ALBs are higher than LMBs and LIBs due to the higher weight ratio of inactive materials.This empirical energy density model is also applied into the practical system and provide intuitional results to guide the battery design for higher energy density.

Study on the mechanism of rapid formation ofu ultra-thick tribofilm by CeO_(2)nano additive and ZDDP

CeO_(2)nanoparticles are potential anti-wear additives because of their outstanding anti-wear and load-bearing capacity.However,the shear-sintering tribo-film formation mechanism of oxide nanoparticles limits the tribo-film formation rate and thickness greatly.In this study,by compounding with zinc dioctyl dithiophosphate(ZDDP),ultra-fine CeO_(2)nanoparticles modified with oleylamine(OM)can quickly form 2μm ultra-thick tribo-film,which is 10-15 times thicker than that of ZDDP and CeO_(2),respectively.The ultra-thick tribo-film presents a nanocomposite structure with amorphous phosphate as binder and nano-CeO_(2)as filling phase,which leads to the highest loading capacity of composite additives.The results of adsorption experiments tested by dissipative quartz crystal microbalance(QCM-D)showed that the Ps value of additive has nothing to do with its equilibrium adsorption mass,but is directly proportional to its adsorption rate in 10 s.The compound additive of CeO_(2)and ZDDP presented the co-deposition mode of ZDDP monolayer rigid adsorption and CeO_(2)viscoelastic adsorption on the metal surface,which showed the highest adsorption rate in 10 s.It is found that the tribo-film must have high film forming rate and wear resistance at the same time in order to achieve super thickness.Cerium phosphate was formed from ZDDP and CeO,through tribochemistry reaction,which promotes the formation of an ultra-thick tribo-film with nanocomposite structure,which not only maintains the low friction characteristics of CeO,but also realizes high Pg and high load-carrying capacity.

急倾斜特厚煤层冲击地压防治探索与总结

急倾斜特厚煤层开采顶板破断运动复杂,应力和能量演化规律特殊,在深部“三高一扰动”影响下,冲击地压防治不容乐观。基于某矿2016年冲击地压事故后急倾斜特厚煤层水平分段开采冲击地压防治经验,从急倾斜特厚煤层水平分段开采冲击地压发生机理、瓦斯突出与冲击地压综合防治和冲击地压管理详细介绍了该矿7年来急倾斜特厚煤层冲击地压防治经验。冲击地压发生机理方面,建立了顶板岩层倾斜悬臂梁模型,揭示了顶、底板覆岩结构破断失稳演化过程,划分了夹持煤体受力状态分区,提出了急倾斜特厚煤层冲击“夹持理论”。瓦斯突出与冲击地压综合防治方面,基于冲击地压灾害控制解危技术的强度弱化减冲理论,结合原有防突措施体系,提出了既能防冲且对防突有利的解危措施,形成了某矿瓦斯/CO_(2)突出-冲击地压“双防”技术体系,建立了适用于某矿急倾斜特厚煤层水平分段开采的冲击地压防治体系,以钻屑量和瓦斯吸解值验证了瓦斯突出防治的强度保障,同时以加强实施卸压措施工作面的微震事件分布及各能级总频次和能量对比,论证说明了卸压方案防治效果的有效性。冲击地压管理方面,形成了预测评价、监测预警、治理预防、效果检验、安全防护和教育培训“六位一体”综合防治架构,基于《煤矿安全规程》和《防治煤矿冲击地压细则》等各项规定,制定了Q/YJMD-—FC 0104-2022《窑街煤电集团有限公司煤矿冲击地压防治第四部分:冲击地压防治技术规范》。

巨厚煤层物质组成特征与成因机制——以柴北缘鱼卡地区中侏罗统为例

厚煤层蕴含着丰富的地质信息,在全球碳循环中扮演着重要的角色。国内外深时地层中厚煤层广泛分布,近年来其成因机制逐渐成为煤地质学的研究热点。为明晰等时层序地层格架中的巨厚煤层的物质组成特征与形成机理,选取柴北缘鱼卡地区中侏罗统层序S1湖侵体系域发育的巨厚煤层M7为研究对象,等间隔连续采样并进行室内显微组分与矿物鉴定,依据煤层关键界面的识别原理、显微组分与矿物的古环境指示意义进行综合分析。结果显示:显微组分中镜质组体积分数最高(48.5%),惰质组体积分数同样较高(37.22%),类脂组所占比例很低,仅为3.32%。矿物组分体积分数较为稳定,平均值为10.96%。依据煤层与碎屑沉积的交替出现、显微组分与矿物体积分数在垂向上的变化趋势,识别出了多种关键界面,包括陆化面(TeS)、陆地暴露面(ExS)、沼泽化面(PaS)、湖侵淹没面(GUTS)与可容空间转换面(ARS)。沿沉积倾向在向陆与向湖方向分别选择钻孔,与鱼卡煤矿对比分析沼泽环境垂向演化过程。鱼卡煤矿巨厚煤层M7识别出4个沉积旋回,向陆以及向湖方向的YQ6–22与YQ6–12中由陆源碎屑、湖相沉积所分隔的M7–1—M7–3则均识别出3个沉积旋回。发现了巨厚煤层中蕴含的高分辨率层序,经过分析划分为4个四级层序,结合煤层中关键界面所对应的层序界面,揭示了巨厚煤层的成因机制。建立了层序地层格架中的多期泥炭沼泽垂向叠置模式,可进一步应用于国内外更多深时地层中巨厚煤层的研究。

特厚煤层底板断层破坏与顶板垮断联动效应的CFDEM模拟研究

特厚煤层采场空间大、覆岩扰动范围广,顶板垮断产生的强扰动加卸荷载易导致底板断层破坏加剧。通过数值模拟研究特厚煤层底板断层突水与顶板垮断联动效应机理规律是开展水害防治的基础,关键在于掌握加卸载下岩体渐进破坏与裂隙流耦合特征。构建加卸载下拉、剪损伤演化方程,结合有效偏/球应力为基本变量的屈服准则与塑性势函数,得到完整岩块的塑性损伤本构;建立拉/剪、混合型加卸载过程中塑性位移与强度劣化关系,以平方拉剪应力与B-K准则为初始、完全断裂准则,形成非贯通裂隙断裂本构;提出岩块分离、压缩、剪切判据,结合实验数据建立离散块体间挤压、剪切摩擦本构与剪胀方程。基于质量/动量守恒、状态方程,并结合流体体积与浸没边界方法,形成裂隙岩体气−水二相流模拟理论。由此形成CFDEM数值计算程序,并将加卸载下塑性损伤、断裂、挤压/摩擦、流体属性分别赋予实体单元(岩块)、黏聚力单元(非贯通裂隙)、接触对(贯通裂隙)、欧拉单元(水和气)。根据宁武煤田北部矿区工程地质条件,建立特厚煤层底板断层突水与顶板垮断联动效应数值计算模型。结果表明:①CFDEM耦合程序及相应的理论模型可数值实现特厚煤层覆岩及底板断层从(准)连续体到离散体转化,以及地下水在裂隙中运移;②模拟条件下特厚煤层含断层底板的采动裂隙包络线呈w形,最深处超过55 m位于断层及其上盘,最浅处23 m位于断层下盘,而无构造底板处的破坏深度为24~36 m,已导通奥灰含水层;③特厚煤层底板普遍出现二次破坏现象。表现为无构造底板在超前工作面处破坏深度为24.0~29.3 m,但在采空区内普遍增加至31.5~36.0 m;断层及其上盘在超前工作面处裂隙总开度为0.34~0.86 m,但在采空区内迅速增加至3.6 m,形成突水优势通道。④底板断层突水与顶板垮断联动效应的根源在于覆岩高位关键岩层垮断失稳、砌体梁下沉与二次断裂,并导致底板二次破坏,突水风险加剧。

黄陇煤田典型特厚煤层综放开采涌水机理与导水裂隙带发育规律

黄陇侏罗纪煤田厚煤层开采导水裂隙带发育高度大,易导通上覆白垩系洛河组巨厚砂岩含水层,区内青岗坪煤矿回采期间出现典型的“脉冲式”涌水特征,给矿井的安全回采造成严重影响。以青岗坪煤矿42105综放工作面为研究对象,采用3DEC离散元模拟、钻孔冲洗液漏失量、综合物探以及钻孔电视相结合的实测方法,对工作面回采过程中覆岩导水裂隙带和离层发育规律进行研究,探究该典型地质条件下矿井的涌水机制与导水裂隙带发育特征。结果表明:42105工作面导水裂隙带受覆岩周期性垮落影响不断向上发育,洛河组孔裂隙砂岩静储水不断释放,间歇性涌入工作面,形成幅值稍低的“脉冲式”涌水;在采动影响下巨厚砂岩含水层内不断出现离层,导水裂隙带导通砂岩含水层离层积水区,致使涌入工作面的瞬时涌水量突增,形成幅值较高的“脉冲式”涌水。结合现场钻孔冲洗液漏失量实测、综合物探以及钻孔电视结果,揭示了青岗坪煤矿洛河组孔裂隙砂岩静储水与离层水叠加影响的“脉冲式”涌水机理,确定导水裂隙带的最大发育高度为316.83~333.00m,裂采比为30.17~31.71。研究结果对于类似地层条件下矿井涌水的防治和安全高效回采具有指导意义。

大变幅加卸载下特厚煤层底板断层突水机理模拟研究

特厚煤层采场空间大、扰动范围广,强烈大变幅荷载易导致底板断层破裂加剧并诱发水害。数值模拟是揭示特厚煤层底板断层活化与突水机理的重要方法,准确反映大变幅加卸载下岩体破裂与裂隙水耦合特征是其合理性的关键。构建损伤变量与塑性应变、应力之间的相关关系,得到完整岩块的拉、加压卸载损伤演化方程;以平方拉剪应力与Benzeggagh-Kenane为初始、完全断裂准则,建立塑性位移与强度劣化关系,建立加卸载韧性断裂本构关系;基于实验数据建立贯通裂隙加卸载剪切本构关系。以基本方程与状态方程为基础,结合浸没边界方法,形成裂隙岩体水力学模拟理论。由此编制流体动力学-有限离散元CFD-FDEM耦合程序,模拟研究特厚煤层底板断层活化突水过程。结果表明:CFD-FDEM耦合程序可数值实现特厚煤层底板断层从(准)连续体到离散体转化,以及断层带裂隙水运移过程。底板断层采动破坏包络线呈W形,最深位于断层及其上盘(48.6m),最浅位于断层下盘(23m)。特厚煤层采场底板断层及其上盘受到较大超前集中应力,而后在采空区内大幅卸载,导致该位置出现显著二次破坏,并形成主要导水通道。研究成果为特厚煤层工作面底板断层水害防治提供理论支撑。

Microstructure and mechanical properties of double-side friction stir welded 6082Al ultra-thick plates

In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-side FSW butt joint with more attention paid to the local characteristic zones.It was shown that a phenomenon of microstructural inhomogeneity existed in the nugget zone(NZ)through the thickness direction.The grain size presented an obvious gradient distribution from the top to the bottom for each single-pass weld,and the microhardness values decreased from both surfaces to the middle of the NZ.The lowest hardness zone(LHZ)exhibited a"hyperbolical"-shaped distribution extending to the middle of the NZ.Similar tensile properties were obtained in the three sliced specimens of the FSW joint,and the joint coefficient reached about 70%which achieved the same level as the conventional FSW Al alloy joints.Finite element modeling proved that the"hyperbolical"-shaped heat affected zone(HAZ)was beneficial to resisting the strain concentration in the middle layer specimen which helped to increase the tensile strength.Based on the analysis of the hardness contour map,tensile property and microstructural evolution of the joints,an Isothermal Softening Layer(ISL)model was proposed and established,which may have a helpful guidance for the optimization on the FSW of ultra-thick Al alloy plates.

高性能特厚板的研发

现有特厚板强度较低,低温韧性较差。研发了一种碳质量分数为0.065%的120 mm特厚钢板。研究了轧制加热温度和非再结晶区轧制总压下率对钢板奥氏体晶粒尺寸、显微组织和力学性能的影响。结果表明:在1200℃以下加热的钢板奥氏体晶粒长大不明显;在1250℃加热的钢板奥氏体晶粒平均尺寸为111μm,最大为295μm;随着非再结晶区轧制总压下率的增大,钢板铁素体增多,组织细化。通过控制加热温度和非再结晶区轧制总压下率试制的120 mm厚钢板屈服强度大于390 MPa,抗拉强度大于510 MPa,-60℃冲击吸收能量大于200 J,表面和表面以下50 mm处韧-脆转变温度低于-80℃。

超厚料层烧结过程固体燃料的分布规律

铁矿烧结以固体燃料作为主要热量来源,其热量高效利用对于烧结节能减排具有重要意义。本文聚焦超厚料层烧结条件下固体燃料在料层中的分布特性,系统解析其在泥辊宽度方向以及料层高度方向的分布规律。结果表明:沿泥辊宽度方向,整体混合料粒度中间偏细、两侧略粗,而含碳量则为中间偏高、两侧略低;布料之后,台车宽度方向混合料粒度组成和含碳量与泥辊对应位置处的混合料规律一致;在料层高度方向上,自上而下混合料粒度整体呈增大趋势,含碳量则逐渐减小,由于泥辊与九辊布料的偏析程度有限,在部分高度处粒度与含碳量会出现波动;利用台车高度方向混合料的粒度组成和泥辊下料处各粒级的含碳量计算出沿料层高度方向的燃料分布,与实际规律基本一致。研究结果可为超厚料层烧结过程固体燃料的优化分布提供指导。

直线加速器机房超厚大体积混凝土温度裂缝控制技术

直线加速器机房的主屏蔽墙厚度达3.2m,顶板厚度达1.8m,超厚混凝土结构防辐射性能要求高,为控制直线加速器机房大体积混凝土温度裂缝,提出了原材料选取、配合比优化、混凝土浇筑和振捣等混凝土硬化前控制措施,浇筑前在超厚墙体和楼板结构内预先安装了温度监测系统和冷却水循环降温管网,冷却水循环降温管网的水循环阀门与温度监测系统的报警模块通过基站网络进行连接,智能控制循环管网内冷却水流动和冷却水温度。基于实时温度监测结果,采用冷却水智能循环管网系统对硬化后混凝土进行智能化控温,解决了混凝土中心部位温度和内外温差过大问题,有效保证了超厚大体积混凝土防辐射性能要求。

库车山前超深巨厚致密砂岩纵向细分层改造技术

塔里木油田库车山前白垩系储层为超深巨厚裂缝性致密砂岩储层,天然裂缝发育,非均质性强,已改造井产气剖面测试显示常规笼统改造纵向厚储层动用不充分,产能释放不彻底。为了解决这一问题,对于油层厚度大且中间有明显隔层的井可实施分层压裂,提高纵向改造程度。通过工程地质一体化研究,利用多种测井数据,建立了一套多尺度近远井裂缝精细识别方法;基于钻井漏失量与产量关系认识,建立了一套综合考虑构造位置、钻井井漏、裂缝发育情况、力学活动性等资料的储层评估分类方法;通过双封隔器管柱力学精细校核,增加伸缩管,优化暂堵材料粒径,形成了“机械+暂堵”软硬分层压裂技术。该技术实现了巨厚储层高效动用,应用20口井,改造后单井产气量由6.7×10^(4)m^(3)/d提高至34.0×10^(4)m^(3)/d,平均增产4倍,提产效果显著,为巨厚致密砂岩储层高效开发提供了技术支撑。

基于机器学习的急倾斜巨厚煤层掘进巷道冲击地压预测方法

针对急倾斜巨厚煤层掘进巷道冲击地压前兆信息挖掘不充分的困境,以新疆乌东煤矿急倾斜巨厚煤层掘进巷道的冲击危险预警为背景,探究了多项物理指标的演化规律,采用BP神经网络、随机森林(RF)、支持向量机(SVM)、梯度提升决策树(GBDT)等4种机器学习算法,分别建立了急倾斜巨厚煤层掘进巷道冲击地压的预测模型,并对各模型预测性能进行了验证和实例分析,明确了掘进条件下神经网络算法对急倾斜巨厚煤层各指标的敏感性分布。研究结果表明:机器学习算法能够有效提取出各物理指标发展趋势中蕴含的冲击前兆特征其中BP神经网络算法的建模精度最高,相较于其他模型平均绝对误差分别降低了58.44%55.64%,26.37%;R^(2)分数分别提高了11.25%,8.37%,3.66%;依据BP神经网络算法得到的各物理指标敏感性排序分别为A(b)值、b值、矿震活动度S值、等效能级参数EEM值、缺震值、算法复杂性AC值;应用R值评分法对乌东煤矿急倾斜巨厚煤层掘进巷道的冲击预警进行了效能验证结果表明该模型预测准确率较好,总体预测准确率为90.65%,并成功预测了掘进期间的两次大能量事件,该方法适用于急倾斜巨厚煤层掘进巷道的防冲预警,建立的模型对于冲击地压危险的预测有着较好的潜力,研究结果可为类似条件下急倾斜煤层冲击危险的演化发展提供参考。

巨厚坚硬岩层运移对采场超前支承压力影响实验研究

为了揭示采场超前支承压力在受巨厚坚硬岩层运移影响之后的演化规律和变异特征,以杨柳煤矿典型巨厚坚硬岩层赋存条件为模型,运用物理模拟和机械模拟实验方法进行模拟研究,并与无巨厚坚硬岩层的采场模型进行比较。通过研究发现:采场中巨厚坚硬岩层对其支承压力的影响,主要集中在巨厚坚硬岩层发生破断之前,其应力集中程度高、影响范围广、影响程度剧烈;临近巨厚坚硬岩层破断前,覆岩中有巨厚坚硬岩层时的超前支承压力峰值和影响范围分别为无巨厚坚硬岩层时的1.15倍和1.9倍;巨厚坚硬岩层处于稳定状态时或已发生破断后,采场支承压力峰值和影响范围相对无巨厚坚硬岩层采场较小,对采场超前支承压力的影响相对较弱;支承压力峰值的增大势必会使采场前方煤壁的影响范围增大。

特厚煤层小煤柱稳定性及合理护巷宽度分析

针对特厚煤层小煤柱稳定性差的问题,以一煤矿为例,介绍一种特厚煤层小煤柱稳定性及合理护巷宽度分析方法。首先,将煤矿作业面各岩层密度、抗拉强度等参数录入到FLAC(Fast Lagrangian Analysis of Continua)软件内,由该软件自动构建出煤层三维立体模型,之后以此为基础,根据作业面开采情况分别向模型施加一定应力,由软件自动对模型掘进巷道、回采阶段及小煤柱巷道围岩力学特性进行分析,以寻找出整个巷道内的薄弱点,最后根据力学特征分析结果,设计出最佳的小煤柱巷道支护方案,提升整个特厚煤层的稳定性,防止煤矿开采过程中出现巷道坍塌等问题,具有一定的应用价值。