在绿色储能技术领域，二次电池不仅为可再生能源的规模化应用提供了坚实的支撑，还显著降低了化石燃料的依赖程度。锂离子电池虽凭借高能量密度占据主导地位，但其主流石墨负极面临容量逼近理论极限、层状结构易因溶剂化锂离子共插层剥离破坏两大瓶颈。相比之下，硬炭（Hard Carbon，HC）具有较大的碳层间距，因而可实现Li⁺的快速传输以提升倍率性能；其内部的闭孔结构有助于储存更多Li⁺，获得更高的可逆储锂容量；无序的微晶结构通过锂离子嵌入/脱出反应储锂，因此不存在溶剂化锂离子共插层而导致的结构破坏，可具有较高的电解液兼容性。然而，现有研究多聚焦HC在钠离子电池中的储钠机制与材料制备，锂电领域缺乏研究。基于此，本论文系统研究了硬炭作为锂离子电池负极的闭孔填充储锂机制和有机电解液兼容性研究，开展了以下三方面研究内容：

使用石墨和软炭材料为参照对象，系统研究了硬炭的电化学储锂行为与特性,发现硬炭拥有在0 V以下的平台容量。具体研究发现，截止锂化电压为0.01 V时，硬炭呈斜坡型储锂曲线，可逆比容量200 mAh g⁻¹；截止电压0 V并增加恒压锂化时，电池呈现平台加斜坡型储锂曲线；通过控制不同储锂时间进而调控储锂容量，硬炭可在0 V以下持续锂化，在约450 mAh g⁻¹时析锂，最大安全锂化容量400 mAh g⁻¹。石墨和软炭在0 V以下过放电易析锂，仅硬炭可在低电位可逆储锂。电化学分析证实硬炭通过闭孔储锂，低电位区（~0.1 V）具备约200 mAh g⁻¹平台容量，平台加斜坡机制使可逆容量达400 mAh g⁻¹。硬炭半电池脱锂性能测试中，在8 A g⁻¹的容量保持率89.77%，显著优于石墨（8 A g⁻¹时仅40.8%）。基于该机制的硬炭全电池评测表明：1C倍率循环1000次后容量保持率93.19%。

基于硬炭负极与电解液的兼容性优势，系统研究了硬炭负极与PC（碳酸乙烯酯，Propylene Carbonate，PC）溶剂的兼容性，构建了PC基功能电解液体系以提升锂离子电池的高电压稳定性和低温性能。首先通过将PC溶剂与其他线性碳酸酯溶剂混合配制电解液，测试结果表明硬炭在PC基电解液中循环稳定，纯PC溶剂亦可储锂循环。基于此，配制了PC基功能电解液（1 M LiPF₆ in PC：EC：DMC：EMC，23：10：33：33），使用该电解液、硬炭负极及高电压钴酸锂组装锂离子全电池，测试结果表明4.45 V循环500圈容量保持率92.24%，优于传统EC基（87.06%）；-20℃循环200圈容量保持率78.85%，显著优于EC基（8.98%）。另一方面，设计了基于PC的弱溶剂化电解液（1 M LiFSI + 0.5 M LiPF₆ in PC：EMC，1：9（摩尔比），以增强快充性能。该电解液体系的全电池测试在200圈循环后的容量保持率（97.51%）优于对比样EC DMC11（90.15%）。

采用水热法制备具有空心结构的硬炭微球，以探究硬炭材料在闭孔填充机制储锂的基础上是否能利用其内部的空心结构沉积锂金属以实现更高可逆储锂容量。研究结果表明，在中温（800℃）碳化制备的硬炭微球通过闭孔填充机制贡献的储锂容量较少，而高温1400℃碳化后硬炭微球由于具有更多的闭孔结构，因而可通过闭孔填充机制贡献更高的储锂比容量。进一步进行锂化时，锂金属沉积于微球外表面而非内部空心结构。基于层间嵌入和闭孔填充机制的储锂行为，HCS1400硬炭微球可实现450 mAh g⁻¹的最大储锂可逆比容量，其中平台区贡献200 mAh g⁻¹。使用该硬炭微球作为负极组装锂离子全电池，500圈时的容量保持率为83.68%，循环稳定性优异。

综上所述，本论文基于硬炭材料的结构特点，开展了电化学储锂时的闭孔填充储锂机制和有机电解液兼容性研究，相关研究结果可为硬炭负极的应用及锂离子电池功能性提升提供理论依据。

In the field of green energy storage technology, secondary batteries not only provide a solid support for the large-scale application of renewable energy but also significantly reduce the reliance on fossil fuels. Although lithium-ion batteries have dominated the market due to their high energy density, their mainstream graphite anodes face two major bottlenecks: the capacity is approaching the theoretical limit, and the layered structure is prone to damage due to the intercalation of solvated lithium ions. In contrast, hard carbon (HC) has a larger carbon layer spacing, enabling rapid Li+ transmission and enhancing rate performance. Its closed pore structure helps store more Li+ and achieve higher reversible lithium storage capacity. The disordered microcrystalline structure stores lithium through the lithium ion intercalation/deintercalation reaction, thus avoiding structural damage caused by the intercalation of solvated lithium ions and having high compatibility with the electrolyte. However, existing research mostly focuses on the sodium storage mechanism and material preparation of HC in sodium-ion batteries, with a lack of studies in the lithium battery field. Based on this, this paper systematically studies the closed-pore filling lithium storage mechanism and organic electrolyte compatibility of hard carbon as the anode of lithium-ion batteries, and conducts the following three aspects of research:

Taking graphite and soft carbon materials as reference objects, the electrochemical lithium storage behavior and characteristics of hard carbon were systematically studied, and it was found that hard carbon has a platform capacity below 0 V. Specifically, when the lithiumation cut-off voltage is 0.01 V, hard carbon shows a sloping lithium storage curve with a reversible specific capacity of 200 mAh g⁻¹; when the cut-off voltage is 0 V and constant voltage lithiumation is added, the battery shows a platform plus sloping lithium storage curve; by controlling different lithium storage times to regulate the lithium storage capacity, hard carbon can continue to lithiumate below 0 V, and lithium plating occurs at about 450 mAh g⁻¹, with a maximum safe lithium storage capacity of 400 mAh g⁻¹. Graphite and soft carbon are prone to lithium plating when over-discharged below 0 V, only hard carbon can reversibly store lithium at low potentials. Electrochemical analysis confirmed that hard carbon stores lithium through closed pores, with a platform capacity of approximately 200 mAh g⁻¹ in the low potential region (~0.1 V), and the platform plus sloping mechanism enables a reversible capacity of 400 mAh g⁻¹. T In the delithiumization performance test of hard carbon half-cell, the capacity retention rate of 8 A g⁻¹ was 89.77%, which was significantly better than that of graphite (only 40.8% at 8 A g⁻¹). The evaluation of hard carbon whole battery based on this mechanism shows that the capacity retention rate is 93.19% after 1000 cycles at 1C rate.

Based on the compatibility advantage of hard carbon anodes with electrolytes, the compatibility of hard carbon anodes with PC (propylene carbonate, PC) solvents was systematically studied, and a PC-based functional electrolyte system was constructed to improve the high-voltage stability and low-temperature performance of lithium-ion batteries. Firstly, by mixing PC solvents with other linear carbonate solvents to prepare electrolytes, the test results showed that hard carbon has stable cycling in PC-based electrolytes, and pure PC solvents can also store lithium and cycle. Based on this, a PC-based functional electrolyte (1 M LiPF₆ in PC:EC:DMC:EMC, 23:10:33:33) was prepared. Using this electrolyte, hard carbon anodes, and high-voltage lithium cobalt oxide, lithium-ion full cells were assembled. The test results showed that after 500 cycles at 4.45 V, the capacity retention rate was 92.24%, which is superior to the traditional EC-based (87.06%); after 200 cycles at -20°C, the capacity retention rate was 78.85%, significantly better than the EC-based (8.98%). On the other hand, a weak solvation electrolyte based on PC (1 M LiFSI + 0.5 M LiPF₆ in PC:EMC, 1:9 (molar ratio)) was designed to enhance fast charging performance. The full-cell test of this electrolyte system showed a capacity retention rate of 97.51% after 200 cycles, which was superior to that of the comparison sample EC DMC11 (90.15%).

Hollow-structured hard carbon microspheres were prepared by a hydrothermal method to investigate whether the internal hollow structure of hard carbon materials could be utilized to deposit lithium metal and achieve a higher reversible lithium storage capacity on the basis of the closed-pore filling mechanism. The results indicated that the hard carbon microspheres prepared by carbonization at a medium temperature (800°C) contributed less lithium storage capacity through the closed-pore filling mechanism, while the hard carbon microspheres carbonized at a high temperature of 1400°C had more closed pores and thus could contribute a higher reversible lithium storage capacity through the closed-pore filling mechanism. During further lithiation, lithium metal was deposited on the outer surface of the microspheres rather than in the internal hollow structure. Based on the interlayer insertion and closed-pore filling mechanisms, the HCS1400 hard carbon microspheres achieved a maximum reversible lithium storage capacity of 450 mAh g⁻¹, with a contribution of 200 mAh g⁻¹ from the plateau region. When assembled into lithium-ion full cells using these hard carbon microspheres as the anode, the capacity retention rate was 83.68% after 500 cycles, demonstrating excellent cycling stability.

In summary, this paper conducted research on the closed-pore filling lithium storage mechanism and organic electrolyte compatibility of hard carbon materials based on their structural characteristics. The relevant research results can provide a theoretical basis for the application of hard carbon anodes and the functional improvement of lithium-ion batteries.