锂二次电池技术已经成为了能源、交通、航空航天、绿色建筑、智能装备等领域的关键支撑技术。析锂问题制约着锂离子电池在低温、快充等苛刻条件下的应用，枝晶状的锂沉积限制着金属锂电池的实用化。理清电化学条件下锂不可控沉积的决定因素和设计锂形核、生长全过程调控策略是实现锂电池中锂沉积高效调控的关键。针对锂形核过程，本文明确稀疏、不均匀形核加剧最终形貌的不均匀，并提出界面亲锂性策略调控锂形核。对于氮掺杂碳材料体系，氮掺杂位点的局部偶极增强锂离子与骨架间离子–偶极作用力，降低锂形核能垒，吸附锂离子使其定向形核。基于上述研究，设计原子级别周期排布亲锂位点的负极骨架，通过优化负极骨架材料亲锂性和导电性实现了电化学条件下均匀、致密的锂形核。针对锂生长过程，本文提出了一种扩散–反应竞争机制，以揭示锂沉积不同形貌形成机制。基于理论计算与实验，控制锂沉积过程中扩散和反应过程，获得了锂沉积形貌与扩散速度和反应速度的关系，证明了扩散和反应步骤协同决定了固态电解质界面层下方的离子浓度，从而决定锂沉积最终形态。该机制为金属锂电池中锂枝晶抑制策略和锂离子电池中析锂抑制策略提供了理论指导。基于对锂形核与锂生长调控机制的研究，理性设计了同轴-交织复合亲锂负极，该骨架具有高导电性、亲锂性、丰富的离子传输通道、以及在锂沉积和脱出过程中的机械和化学稳定性，实现了超长时间的循环稳定性；提出了在苛刻条件下的锂离子电池引入反向脉冲的设计思路，调控锂离子分布且在低温下加热电池，强化锂离子输运过程，从而起到抑制/调控锂沉积的作用。该思路不仅能改善锂离子电池负极的锂沉积行为，更能应用在电动汽车、储能电站和建筑内的锂离子电池中，通过双向脉冲聚合参与电网调频等高收益、低容量和高功率需求的中短时间尺度的电网服务。综上所述，本论文聚焦在锂电池中锂沉积的全过程调控，明确稀疏、不均匀形核会加剧锂枝晶的生长，从而提出了界面亲锂改性策略，实现了锂均匀、致密形核；提出了决定锂沉积呈现不同生长形貌的扩散–反应竞争机制，揭示了枝晶状锂沉积的决定因素即是沉积过程处于扩散控制。基于上述基础研究，从原理到器件层面，系统地实现了电化学条件下可控的锂沉积反应，推进金属锂负极实用化进展，指导苛刻条件下锂离子电池的高效使用策略。
The lithium battery technology has enabled the development of energy, transportation, aerospace, green building, and intelligent equipment. However, lithium plating hinders the application of lithium-ion batteries under harsh conditions such as low temperature and fast charging. On the other hand, the dendritic lithium plating limits the practical application of lithium metal batteries. Clarifying the determinants of uncontrollable lithium deposition and the regulation strategies for the uniform lithium deposition is the key to realize the efficient regulation of lithium deposition in lithium batteries.In view of the lithium nucleation process, this work made it clear that the sparse and heterogenous lithium nucleation exacerbated the uneven lithium deposition. Therefore, an interfacial lithiophilic strategy was presented to control the uniform and dense lithium nucleation. For nitrogen-doped carbon materials, the local dipole of nitrogen-doped sites can enhance the ion-dipole interaction between lithium ions and lithium hosts, thus reducing the energy barrier of lithium nucleation and guide the directional nucleation of lithium ions. Based on above mechanism research, the lithium host with periodic arrangement of lithiophilic sites at the atomic level was designed. Meanwhile, the lithiophilicity and conductivity of the lithium host were optimized to achieve the uniform and dense lithium nucleation.Aiming at the lithium growth process, a diffusion–reaction competition mechanism was proposed to reveal the rationale of different lithium morphology. By controlling the rate-determining step (diffusion or reaction) of lithium deposition, various lithium deposition scenarios were realized, where the diffusion–controlled process tends to form dendritic lithium deposition while the reaction-controlled process leads to spherical lithium deposition. This study shed fresh light on the dendrite-free lithium batteries.Based on the understanding of regulation mechanism of lithium nucleation and growth processes, a coaxial-interweaved hybrid Li anode was constructed following the multiscale design strategy regarding coaxial lithiophilic modification and 3D interweaved scaffold and realized the long-lifespan cycle stability. The coaxial-interweaved Li host affords high conductivity and lithiophilicity, abundant channels for ion transportation and Li composition, and mechanical and chemical stability during Li plating and stripping. This work introduced the reverse pulses into charge protocol of lithium-ion batteries under harsh conditions, which regulation the distribution of lithium ions, heating the batteries at low temperature, and strengthening the mass transport process. Therefore, this strategy could prevent/regulate lithium deposition. In addition to improving the lithium deposition behavior of lithium-ion batteries, this method could also enable lithium-ion batteries distributed in electric vehicles, energy storage stations and buildings to participate in the frequency regulation service of high-proportion renewable energy grids in the future.To sum up, this thesis focused on the regulation strategies of the whole process of lithium deposition in lithium batteries. It was clear that sparse and uneven nucleation aggravated the lithium dendrite growth. Therefore, an interface lithophilic modification strategy was proposed to achieve uniform and dense lithium nucleation. The diffusion–reaction competition mechanism that determined the different growth morphologies of lithium deposition was raised. Based on the above basic researches, this thesis systematically realized the controllable conversion reaction of lithium under electrochemical conditions from microscale to macroscale, which would promote the practical application of lithium metal anode and guide the high-efficient utilization of lithium-ion batteries under harsh conditions.
