经过电解液，嵌入到正极中的石墨层间中。
The discharge reverses this process where the electrons pass around the external circuit to power various systems. 放电过程是上述过程的逆过程，电子经过外电路给不同系统提供能量。The rechargeable lithium-ion battery is an ultimate representation of solid-state chemistry in action that started with the discovery of intercalation compounds, such as LixMO2 (M = cobalt or nickel) which were initially proposed by Goodenough and are still widely used today [1,2]. 可充电锂离子电池是一个固态化学的终极的代表。它开始于插层化合物的发现，比如插层化合物LixMO2 (M = 钴 or 镍)最早是Goodenough提出的直到现在还在广泛应用。 The discovery of low-voltage, lithium intercalation, carbonaceous materials that are highly reversible led to the commercialization of LixC6/Li1?xCoO2 cells by Sony in 1991 [3]. 1991年sony公司发现了低电压的高度可逆的锂插层化合物，实现了LixC6/Li1?xCoO2 电池商业化。 The energy conversion in the so-called rocking-chair cells is completed via the following reactions [3]: 所谓的摇椅电池中，能量转化通过如下反应实现。
Typical lithium-ion cells produce 3.7 V and demonstrate a capacity and power about 150 Ah/kg and over 200 Wh/kg, respectively [4]. 典型的锂离子电池电压为3.7V，电量为150 Ah/kg 功率大于 200 Wh/kg。The favorable electrochemical performance in energy/power densities and advancements in system design and manufacturing have made the early lithium-ion battery a great success for mobile electronics in spite of the remaining challenges.虽然锂离子电池方面还存在很多难题，但是它在能量/功率比密度电化学性能方面是令人满意的，再加
上系统设计和制造方面取得的进展，这使的早期锂离子电池在移动电子设备上取得了巨大成功 For a better understanding, a brief historical account of the development of lithium-ion battery technology over the past 30 years is needed. Like most innovations, there were a number of developments that led to mature lithium- ion battery technology.为了更好的理解锂离子电池，我们需要简要的数数锂离子电池技术在过去30年里取得的进展。与其他大部分创新一样，在锂离子电池技术经过了很多的开发才达到了成熟的地步。
Coal analysis
Typical coal analysis includes the measurement of moisture, volatile matter, ash and fixed carbon, which is commercially required to measure the physical and chemical properties of coals. There are four types of moisture existed in coals, including (1)surface moisture, which is held on the surface of coal particles, (2) hydroscopic moisture, which is held by capillary action within the micro-fractures of the coal ，(3) decomposition moisture，which is held within the coal‘s decomposed organic compounds and (4) mineral moisture which is partially comprised in the crystal structure of hydrous silicates. The measurement of total moisture is determined by the relative weight loss after one of the following methods, they are (1) heating the coal with toluene (2) drying in a minimum free-space oven at 150°C within a nitrogen atmosphere and (3) drying in air at 100°C to 105°C. Methods is 1 and 2 are suitable for low-rank coals and method 3 is only suitable for high-rank coals. Air may promote the oxidation of low-rank coals during drying.
煤质分析
典型的煤工业分析包括水分、挥发分、灰分及固定碳的测定。在煤中存在四种类型的水分,包括:①表面水,储存在煤颗粒的表面;②吸附性水,通过毛细作用储存在煤的微观框架结构中;③分解水,储存在煤
分解的有机化合物中;④矿物质水分,部分储存在含水硅酸盐的晶体结构中。水分总量的测定通过相对失重获得,可通过下列方法测定:①在甲苯中将煤加热;②在氮气气氛中于150℃千燥;③在空气中于100~105℃干燥。前两种方法适用于低阶煤,而第三种方法适用于高阶煤。在干燥条件下,空气会促进低阶煤的氧化。
Volatile matter of coal is the mixture of hydrocarbons, aromatics and somewhat sulfur that are liberated at high temperature in the absence of air. The measurement of volatile matter is determined by additionally relative weight loss under rigidly controlled standards, normally heating the coal sample to (900±5)°C for 7 min. Ash of coal is the non-combustible residue left after coal is burned. It represents the bulk mineral matter after carbon, oxygen, sulfur and water have been driven off during combustion. The measurement of ash is determined by the relative weight of remaining inorganic materials after coal is burned. The fixed carbon of coal is the carbon found in the material which is left after volatile materials are driven off. It is used as an evaluation of the approximate amount of coke that will be yielded from a sample of coal. The measurement of fixed carbon is determined by the relative weight by subtracting moisture, volatile matter and ash.
挥发分指煤在高温及隔绝空气下所释放出的烃类、芳烃和一些含硫物种的混合物,挥发分的测定是在苛刻条件下[通常将煤样品加热至(900±5)℃并维持7min]额外的相对质量损失。灰分指煤燃烧后残留的非可燃性残渣，它代表着矿物质燃烧后去除碳、氧硫及水分的状况。灰分的测定通过煤燃烧后残留的无机矿物质的相对质量来获得。固定碳指煤在挥发分去除后煤中所残存的碳,其可用于评估煤样中所产焦炭的大致数量,固定碳是煤去除水分、挥发分和灰分之外的部分。
In addition to the above industrial coal analysis, ultimate analysis is used on describing coal elemental composition. For a dried coal, weight percentages of carbon, hydrogen, nitrogen and sulfur are measured. The remainder of the coal sample is designated as oxygen.
除上述煤工业分析外,元素分析可用于描述煤的元素组成。煤干燥后,可测定煤中碳氢、氮、硫及灰分的质量分数。煤样品中的其余组分可被认定为氧。
relative density or specific gravity of the coal depends on the rank of the coal and degree of mineral impurity. There are some different density measurements for porous coals, including true density or particle density, apparent density, bulk density, and in-place density. In general, the measurement of true density or particle density is determined by helium displacement because helium can penetrate all the pores of a given coal sample without any chemical interaction. The measurement of apparent density is determined by weighting and immersing a coal sample into a liquid which was accurately measured before and after. The measurement of bulk density is to divide the total weight of coal particles that assembled in a fixed container by the volume of the container.For coal in the seam, the measurement of in-place density will be determined in term of tons per acre per foot of seam thickness and tons per square mile per food of seam thickness.
煤的相对密度(比重)依赖于煤阶及煤矿纯度。多孔性煤有几种不同的密度表示方式,包括真密度与颗粒密度、表观密度、体积密度和原状密实度。通常,真密度及颗粒密度的测定通过氦气取代获得。这是因为氦气可以穿透给定煤样品的所有孔隙而不与煤发生任何化学作用。煤的表观密度测定是将已知质量的煤浸入液体中,精确测定浸渍前后的液体质量。煤的体积密度是将“固定体积”容器中的煤颗粒质量除以容器体积,煤的原状密实度按照单位面积、单位厚度煤层中煤的质量获得。
It is widely agreed that China possesses the third largest coal resources in the world, behind the United States and Russia. In 2010, China's coal reserve was reported as high as 114. 5 billion tones based on raw coal. Shanxi province has the richest coal reserves in China, followed by Inner Mongolia and Shaanxi province. On a national level, 54% of China's coal reserves are classified as bituminous coaI by volume, versus 29% sub-bituminous and 16% lignite. China is mainly focusing on extraction of bituminous coal and paid less attention on the production of anthracite and lignite. The production of bituminous coal reaches 76% of China's total coal production. The average depth of China 's coal mines is 456 meters. Xinjiang province has more than half of coal reserves located at less than 1000 meters below the surface. Mines in eastern China are particularly deep, with an average depth of 600 meters.
中国拥有世界上第三大煤炭资源,仅次于美国和俄罗斯。2010年,中国煤炭储量达到145亿吨。山西省是中国煤炭资源最丰富省份,其次为内蒙古和陕西。按体积划分,中国褐煤产量相对较低。烟煤的产量可达中国煤总产量的76%。中国煤矿平均深度为456m，其中新疆有一半资源低于地表1000米。中国东部煤矿相对较深，平均深度达600米。
North China contains the vast majority of domestic coal reserves and more than half the population. However, the regions have access to only 20% of national water resources. The distribution of coal and water resources leads to many challenges in meeting demand. The demand of coal is distributed in most parts of China, notably in coastal areas, but the supply of coal is concentrated in northern regions.Average per capital water in China is only 1/8 of the national average and 1/25 of the world average. As for China's mining industry, it has been estimated that the extraction of 1 tonne of coal requires 53~120 liters of water, depending on the location and depth of the coal. An additional 4
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